Characterization of Corrosion on Outdoor-Exposed 

Aluminum Metal-Matrix Composites as a Function of 

Reinforcement Specie and Volume Fraction 

by Ralph P. I. Adler, Daniel J. Snoha, George Hawthorn, 

and Lloyd H. Hihara 

ARL-TR-4372 February 2008 

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Army Research Laboratory 

Aberdeen Proving Ground, MD 21005-5069 

ARL-TR-4372 February 2008 

Characterization of Corrosion on Outdoor-Exposed 

Aluminum Metal-Matrix Composites as a Function of 

Reinforcement Specie and Volume Fraction 

Ralph P. I. Adler and Daniel J. Snoha 

Weapons and Materials Research Directorate, ARL 

George Hawthorn and Lloyd H. Hihara 

University of Hawaii 

Approved for public release; distribution is unlimited.
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Characterization of Corrosion on Outdoor-Exposed Aluminum Metal-Matrix 

Composites as a Function of Reinforcement Specie and Volume Fraction 

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Ralph P. I. Adler, Daniel J. Snoha, George Hawthorn,* and Lloyd H. Hihara*

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Hawaii Corrosion Laboratory, Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, HI 96826 

14. ABSTRACT 

The Hawaii Corrosion Laboratory and the U.S. Army Research Laboratory collaborated to prepare, environmentally expose for 

up to 2 years, and evaluate multivariant sets of metal matrix composites (MMCs). The experimental matrix involved variations 

in particulate volume-percent and particulate reinforcement specie (higher purity green and less-pure black silicon carbide, 

boron carbide, and alumina). The specific objective of this study was to determine, mainly using x-ray powder diffractometry, 

how observed gravimetric variations in corrosion behavior of these sets of MMCs (differentiated by four kinds of reinforcing 

agents with some variations in volume-percent), after relatively heavy-rainfall outdoor exposures in Hawaii, could be related to 

the crystallographic and morphological characteristics of the resulting corrosion products. Compared to the monolithic 

aluminum control specimens, the measured corrosion rates for these MMCs were considerably accelerated (by at least an order 

of magnitude) by the presence and relative amount of these second-phase particulates. The increased kinetics found for these 

MMCs were nominally proportional to the volume fraction of the particulate phase. Other differentials in gravimetric corrosion

rates and corrosion product characteristics were related to the type of reinforcement phase present. 

15. SUBJECT TERMS

corrosion, aluminum metal-matrix composites, silicon carbide, boron carbide, alumina, Bayerite 

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Ralph P. I. Adler 

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(410) 306-0826 

Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18 
iii

Contents 

List of Figures v

List of Tables vi

Acknowledgments vii

1. Introduction 1

2. Experimental Materials and Sample Preparation 2

2.1 MMC Specimens.............................................................................................................2

2.2 Monolithic 6061-T6 Aluminum Alloy Control Specimens ............................................3 

3. Experimental Procedures 3

3.1 Outdoor-Exposure Corrosion Studies .............................................................................3 

3.1.1 Test Site, Corrosion-Exposure Racks, and Gravimetric Measurements ...............3 

3.1.2 Outdoor-Exposure Specimens...............................................................................4 

3.2 X-ray Diffraction (XRD) Characterization of Corrosion Products.................................5 

4. Experimental Results 11

4.1 Microstructural Observations........................................................................................11 

4.2 Gravimetric Observations..............................................................................................11 

4.3 XRD Characterization Studies ......................................................................................11 

4.3.1 Diffraction Scans for Unexposed Substrate Phases ............................................11 

4.3.2 Diffraction Scans for Exposed Samples With Substrate and Corrosion Product 

Phase ...........................................................................................................................17 

4.3.3 Phase Identification of the Corrosion Film on Exposed Substrates ....................18 

5. Discussion – Determining Corrosion Layer Thickness From X-ray Peak Attenuation 

Measurements 18

5.1 Derivation of Thickness Determining Formula.............................................................18 

5.2 Calculated Corrosion-Product Thickness......................................................................20 

6. Conclusions 23

6.1 Outdoor-Exposure Corrosion Rates ..............................................................................23 
iv

6.2 Characterizing the Corrosion-Product Layers...............................................................24 

7. Summary 25

8. References 27

Distribution List 28 
v

List of Figures 

Figure 1. Typical arrangement of Al MMCs on outdoor-exposure rack at test site. ......................4 

Figure 2. Before (left) and after (right) cleaning photos of 40 volume-percent SiC-reinforced 

Al MMC exposed for 90 days....................................................................................................5

Figure 3. XRD scan of virgin monolithic aluminum. .....................................................................6 

Figure 4. XRD scan of virgin 20-volume-percent black-SiC-reinforced Al MMC........................7 

Figure 5. XRD scan of virgin 50-volume-percent black-SiC-reinforced Al MMC........................7 

Figure 6. XRD scan of virgin 20-volume-percent B4C-reinforced Al MMC.................................8 

Figure 7. XRD scan of virgin 20-volume-percent Al2O3-reinforced Al MMC. .............................8 

Figure 8. XRD scan of the front face of 50-volume-percent green-SiC-reinforced Al MMC 

after 12 months of outdoor exposure. ........................................................................................9 

Figure 9. XRD scan of the front face of 50-volume-percent black-SiC-reinforced Al MMC 

after 12 months of outdoor exposure. ........................................................................................9 

Figure 10. XRD scan of the front face of 20-volume-percent B4C-reinforced Al MMC after 

12 months of outdoor exposure................................................................................................10

Figure 11. XRD scan of the front face of 20-volume-percent Al2O3-reinforced Al MMC after 

12 months of outdoor exposure................................................................................................10

Figure 12. Microstructure of virgin 50-volume-percent green-SiC-reinforced Al MMC. ..........11 

Figure 13. Microstructure of virgin 50-volume-percent black-SiC-reinforced Al MMC. ...........12 

Figure 14. Microstructure of virgin 20-volume-percent black-SiC-reinforced Al MMC. ..........12 

Figure 15. Microstructure of virgin 20-volume-percent B4C-reinforced Al MMC......................13 

Figure 16. Microstructure of virgin 20-volume-percent Al2O3-reinforced Al MMC...................13 

Figure 17. Linear x-ray-intensity absorption model. ....................................................................19 

Figure 18. Corrosion film x-ray-intensity absorption model adapted to diffraction geometry. ...20 
vi

List of Tables 

Table 1. Resistivities of selected materials.....................................................................................1 

Table 2. Composition of 6061 and 6092 aluminum alloys.............................................................3 

Table 3. Gravimetric measurements (cleaned specimens)............................................................14 

Table 4. Gravimetric measurements (uncleaned specimens)........................................................14 

Table 5. XRD peak intensities for virgin and exposed 6061 aluminum and Al-SiC MMC 

specimens.................................................................................................................................15 

Table 6. XRD peak intensities for virgin and exposed Al-B4C MMC specimens........................16 

Table 7. XRD peak intensities for virgin and exposed Al-Al2O3 MMC specimens.....................16 

Table 8. Corrosion product thickness as a function of XRD peak intensity attenuations for 

virgin and exposed 6061 aluminum and Al-SiC MMC specimens. ........................................21 

Table 9. Corrosion product thickness as a function of XRD peak intensity attenuations for 

virgin and exposed Al-B4C MMC specimens..........................................................................21 

Table 10. Corrosion product thickness as a function of XRD peak intensity attenuations for 

virgin and exposed Al-Al2O3 MMC specimens.......................................................................22 

Table 11. Comparative values (from averaged diffraction peak results) of corrosion product 

thickness after 12 months of outdoor exposure. ......................................................................22 
vii

Acknowledgments 

The authors are grateful for the support from the Pacific Rim Corrosion Research Program under 

U.S. Army contract DAAE30-03-C-1071 administered through the Army Corrosion Office (by 

Robert Zanowicz, John Theis, and Dr. Joseph Argento), located at Picatinny Arsenal, NJ. We 

also thank our colleagues at the Hawaii Corrosion Laboratory and the U.S. Army Research 

Laboratory for their administrative and technical support.
viii

INTENTIONALLY LEFT BLANK.
1

1. Introduction 

The promising metallurgical concept of incorporating stiff ceramic fiber as reinforcements into 

metallic matrices to produce metal-matrix composites (MMCs) with enhanced properties relative 

to the monolithic metal has been well demonstrated by academia and industry. However, there 

has been relatively less concern that the presence of such second (reinforcing) phases could have 

some compositional (due to electrochemical differences), physical (e.g., large differences in 

electrical resistivity among the ceramic phases, see table 1), and microstructural effects on 

corrosion phenomena and associated kinetics. 

Table 1. Resistivities of selected materials. 

Material Resistivity

(Ω cm) 

Temperature 

(°C) 

Notes Reference 

B4C 101 — Pure (1) 

SiC 10–5 –1013 — Dependant on purity (2) 

Al2O3 >1014 30 99.7% (3) 

TiO2 1013 –1018 25 99.6% (4) 

Numerous MMC components with continuous or discontinuous reinforcing fibers and 

particulates (silicon carbide [SiC], boron carbide [B4C], and alumina [Al2O3]), primarily with 

aluminum alloy (Al) matrices, are already being produced for various applications (5). Al-SiC 

MMCs are generally used in structural and electronic applications, while Al-B4C MMCs and AlAl2O3 MMCs are generally used in structural applications. Each type of reinforcement 

constituent possesses certain advantages and disadvantages. Of these Al MMCs, those with SiC 

reinforcements are the most prevalent. In structural applications, low-purity black SiC is used at 

loadings between 15 and 25 volume-percent. In electronic-packaging applications (5), the major 

function of the SiC, whose reinforcement content ranges from ~30–55 volume-percent, is to 

reduce the MMC coefficient of thermal expansion to values closer to those of electroniccomponent materials such as gallium arsenide. In electronic-grade MMCs, high-purity green 

SiC is preferred for its high thermal conductivity. The green SiC also possesses high electrical 

resistivity and should be less likely to promote any galvanic corrosion of the aluminum matrix as 

compared to black SiC that, because it is less pure, has a lower resistivity. B4C has some 

advantages over SiC in that it is 20% lighter, improves MMC weldability, and is good for 

neutron shielding (5). The relatively low electrical resistivity (6) of B4C (10–1–101 Ω cm) may 

promote galvanic corrosion in MMCs. Al2O3 reinforcements have the advantage of being an 

insulator (>1014 Ω cm) and, thus, should not promote galvanic corrosion with the aluminum 

matrix. However, the density of Al2O3 (6) is more than 20% higher than that of SiC, resulting in 

a heavier MMC for the same volume-fraction reinforcement. 
2

The primary concern, with respect to the corrosion durability of Al MMCs, is that galvanic 

corrosion may occur when the incorporated particles or fibers are conductive or semiconductive 

(7, 8). The galvanic effect of a conductor such as graphite has been generally accepted; whereas, 

galvanic effects of the nonmetallic components such as SiC, a semiconductor with resistivities 

ranging from 10–5 to 1013 Ω cm, depending on its purity (2, 9), are in question. Theoretically, 

when aluminum is coupled with an insulating component such as Al2O3, there should be no 

galvanic effects. B4C has a relatively low resistivity (~1 Ω cm), and, therefore, galvanic 

coupling is likely. For the SiC-reinforced MMCs, the current Hawaii Corrosion Laboratory 

(HCL) scanning vibrating electrode technique and scanning ion-selective electrode technique 

results also indicate a galvanic effect (10). First, there are similar characteristics on the current 

density maps and pH profiles over the localized corrosion regions that formed on 20-volumepercent B4C and 20-volume-percent SiC Al MMCs. Second, the corrosion behavior of 20-

volume-percent Al2O3 Al MMC is different from that of the 20-volume-percent B4C and 20-

volume-percent SiCAl MMCs. Third, the extent of corrosion of 20-volume-percent SiCreinforced Al MMC was lower than that of the 20-volume-percent B4C-reinforced Al MMC. 

That the extent of corrosion of these three MMCs decreased with increasing reinforcement 

resistivities indicates that galvanic effects accelerated the corrosion process. 

Accordingly, the specific objective of this study was to determine the impact of the relative 

volume fraction and reinforcement specie on the bulk corrosion rates of discontinuously 

reinforced Al MMCs relative to a comparable monolithic aluminum alloy after outdoor 

exposures at the highest rainfall (HCL test site at the Lyon Arboretum on Oahu). Further 

characterizations of crystallographic and morphological features of the resulting corrosion 

products, acquired mainly using x-ray powder diffractometry techniques, were used to obtain 

correlations with the gravimetric results. 

2. Experimental Materials and Sample Preparation 

2.1 MMC Specimens 

The discontinuously reinforced aluminum MMCs were fabricated by DWA Aluminum 

Composites (Chatsworth, CA) using nominally identical processing and thermomechanical 

histories to avoid differences in corrosion behavior associated with processing inconsistencies. 

Each custom MMC lot was fabricated using DWA’s proprietary powder metallurgy and hotpressing processing operation forming nominally 3.7-in-diameter billets that were then heat 

treated to the T6 condition. The chemical composition of the 6092 aluminum alloy matrix is 

listed in table 2. Corrosion disk samples, nominally 0.1 in thick, were cut from the billet by 

electrical discharge machining (EDM) followed by abrasive grit-blasting to remove the recast 

layer induced by EDM thermal effects. 
3

Table 2. Composition of 6061 and 6092 aluminum alloys. 

 Solute Concentrations (Volume-Percent Solute by Element)

Alloy Si Fe Cu Mn Mg Cr Zn Ti 

6061 Al 0.4–0.8 0.7 0.15–0.4 0.15 0.8–1.2 0.04–0.35 0.25 0.15 

6092 Al 0.75 0.09 0.83 NA 1.05 NA NA 0.05 

Note: NA = not applicable. 

The MMC particulate reinforcements were green and black SiC, B4C, and Al2O3. The black SiC 

volume fractions were 5, 10, 20, 40, and 50 volume-percent, the green SiC was 50 volumepercent, and the B4C and Al2O3 were 20 volume percent. However, only the 20- and 50-volumepercent black SiC samples were selected for this study to determine the effect of SiC volume 

fraction on corrosion behavior. The 20-volume-percent series of black SiC, B4C, and Al2O3

MMCs compared the effect of reinforcement resistivity on corrosion behavior; likewise for the 

MMCs with 50-volume-percent black and green SiC. 

2.2 Monolithic 6061-T6 Aluminum Alloy Control Specimens 

The control samples were nominally 2- × 2- × 0.125-in coupons machined from wrought sheet 

stock. The 6061 aluminum alloy composition, listed in table 2, was a close match to the powdermetallurgy-produced 6092 aluminum alloy’s composition. 

3. Experimental Procedures

3.1 Outdoor-Exposure Corrosion Studies 

3.1.1 Test Site, Corrosion-Exposure Racks, and Gravimetric Measurements 

MMC and control specimens were exposed to a heavy-rainfall atmospheric test site located in the 

Lyon Arboretum on the island of Oahu. The Lyon Arboretum site is on University of Hawaii 

(UH) property. Test-site maintenance (including changing chloride candles, downloading 

weather data, photography, and/or retrieving specimens) was performed on a monthly basis. 

Test racks were designed and constructed using 316 stainless steel and Trex* materials. Trex is a 

wood-like composite made from recycled wood chips and recycled polyethylene. Test racks on 

UH had Trex slats on a stainless-steel frame. For this corrosion study, the MMC and monolithic 

specimens were exposed at 30° from the horizontal, and each specimen was secured with three 

nylon insulators. 

 *

 Trex is a registered trademark of Trex Company, Inc. 
4

3.1.2 Outdoor-Exposure Specimens 

Each MMC disk (0.1 in thick and ranging in diameter from 3.56 to 3.75 in) was stamped with an 

alphanumeric code using a Telisis Benchmark 320 pin-stamping system. The disks were washed 

in acetone, followed by ultrasonic cleaning in deionized water. After drying, each specimen was 

weighed on a Mettler AE163 electronic balance. The initial weight of each specimen was 

measured in grams to four decimal places. Figure 1 shows a typical arrangement of the MMC 

specimens on a test rack. 

Figure 1. Typical arrangement of Al MMCs on outdoor-exposure rack 

at test site. 

Samples of the eight lots of MMCs were arranged in eight columns of 10 rows, where each 

column contained the same type of MMC. Specimens were placed on the rack with the 

alphanumeric code on the underside (facing down and heretofore referred to as the back face). 

Whenever MMC or control specimens were recovered from the field, they were scanned or 

photographed in the uncleaned state. The disks used for bulk gravimetric corrosion 

measurements were then cleaned in a solution of phosphoric acid (H3PO4), chromium trioxide 

(CrO3), and ultrapure (18.1 MΩ cm) water as described in ISO 8407 (11). The remaining disks 

were stored for further analyses and for characterizing the corrosion products. 
5

For the cleaning operation, specimens were immersed in the just-described mildly heated 

phosphoric acid/chromium trioxide/water solution for 10 min at a temperature between 90 and 

100 °C. They were then ultrasonically cleaned for 30 min in deionized water. After oven drying 

at 21 °C for 20–30 min, the specimens were reweighed on the same Mettler balance to determine 

weight loss. The initial and final weights were used, along with the surface area of each 

specimen to calculate the average weight loss per unit area for each MMC sample. The reported 

weight-loss data was the average value from two replicate samples; the data was reported as an 

average corrosion rate as grams per square meter per day (gmd). Figure 2 shows a macrograph 

of the front (upward facing, environmentally exposed) surface of a specimen before and after 

cleaning. 

Figure 2. Before (left) and after (right) cleaning photos of 40 volume-percent SiC-reinforced 

Al MMC exposed for 90 days. 

In addition to the MMCs at the Lyon test site, 10 6061 aluminum control specimens were also 

exposed for the same durations in order to obtain a nominal baseline corrosion weight loss per 

unit area of a monolithic alloy with a similar composition as the MMC matrix phase. The 

aluminum coupons, measuring 2 × 2 × 0.125 in, were stamped, cleaned, and weighed in the same 

manner as the eight reinforced MMC sample sets. 

3.2 X-ray Diffraction (XRD) Characterization of Corrosion Products 

XRD techniques were used as the major characterization procedure. The primary (metal matrix 

and ceramic reinforcement) phases were readily identifiable from prominent diffraction scan 

peak locations for each MMC and monolithic control sample. Comparing the differences 

between diffraction scans for the matched set of unexposed (virgin) samples with the exposed 

samples provided information about the nature of the corrosion product that overlies the original 
6

substrate. Also, by measuring the decrement in the peak intensities of some major diffraction 

lines from the aluminum alloy substrate, calculations to determine the thickness of the oxide 

corrosion product layer were made. Similarly, the increase in the relative background count 

level of the exposed sample relative to the matched virgin sample provided another empirical 

measure of the overlying oxide thickness. Details about the Debye-Scherrer method to identify 

phases and the basic physics of x-ray absorption used to calculate the overlying oxide thickness 

can be found in Cullity (12). Specific details about calculating the thickness of an overlying 

surface layer of corrosion product from the peak intensity ratios of the exposed and virgin pair of 

samples will be presented subsequently. 

A Philips Analytical powder diffraction system with a model PW1820 vertical goniometer and a 

copper target x-ray tube was used to collect diffraction scans from the Al MMC and monolithic 

aluminum control specimens. The goniometer was arranged with a 1° fixed divergence slit and a 

0.2-mm receiving slit and operated in the step-scan mode with a 0.02° 2θ (diffraction angle) step 

size and a 2-s/step count time. The diffraction scans were acquired over a 2θ range of 

20°–110° with the x-ray generator set at 45 kV and 40 mA. Philips X’Pert software was used for 

data collection and search-match analysis, with the candidate lines (peaks) compared against the 

International Centre for Diffraction Data (ICDD) Powder Diffraction File* for phase 

identification. Please note in figures 3–11 that the diffracted intensity is plotted as counts 

squared to emphasize the presence of low-intensity peaks. Also, the diffraction scans are 

displayed only for the 20°–70° 2θ range to enhance visualization of the x-ray peaks that were 

used for intensity-ratio calculations. 

Figure 3. XRD scan of virgin monolithic aluminum. 

 *

 Powder Diffraction File is a trademark of JCPDS-International Center for Diffraction Data. 
7

Figure 4. XRD scan of virgin 20-volume-percent black-SiC-reinforced Al MMC. 

Figure 5. XRD scan of virgin 50-volume-percent black-SiC-reinforced Al MMC. 
8

Figure 6. XRD scan of virgin 20-volume-percent B4C-reinforced Al MMC. 

Figure 7. XRD scan of virgin 20-volume-percent Al2O3-reinforced Al MMC. 
9

Figure 8. XRD scan of the front face of 50-volume-percent green-SiC-reinforced Al MMC after 

12 months of outdoor exposure. 

Figure 9. XRD scan of the front face of 50-volume-percent black-SiC-reinforced Al MMC after 

12 months of outdoor exposure. 
10

Figure 10. XRD scan of the front face of 20-volume-percent B4C-reinforced Al MMC after 12 months of 

outdoor exposure. 

Figure 11. XRD scan of the front face of 20-volume-percent Al2O3-reinforced Al MMC after 12 months of 

outdoor exposure. 
11

4. Experimental Results 

4.1 Microstructural Observations 

The microstructure of virgin samples is shown in figures 12–16. The various microstructures of 

these MMCs show the discontinuous arrangement of particles and the difference in particle sizes 

dependent on the volume-percent of the MMC. 

Figure 12. Microstructure of virgin 50-volume-percent green-SiC-reinforced 

Al MMC. 

4.2 Gravimetric Observations 

Tables 3 and 4 list the UH site gravimetric data for the 1-year weight-loss results from cleaned 

samples, as well as the weight gains for uncleaned characterization samples for the aluminum 

control samples, the 20- and 50-volume-percent black-SiC samples, the 50-volume-percent 

green-SiC sample, and the 20-volume-percent B4C and Al2O3 samples. 

4.3 XRD Characterization Studies 

4.3.1 Diffraction Scans for Unexposed Substrate Phases 

Typical diffraction scans for virgin samples of the control coupon (figure 3) and two different 

black-SiC (20 and 50 volume-percent) MMCs are shown in figures 4 and 5. The phase-analysis 

software identified the primary phases (Al and SiC) in the unexposed substrate. The Miller 

indices (hkl) and intensities of the corresponding prominent peaks from all the SiC-reinforced 
12

Figure 13. Microstructure of virgin 50-volume-percent black-SiC-reinforced Al MMC. 

Figure 14. Microstructure of virgin 20-volume-percent black-SiC-reinforced 

Al MMC. 
13

Figure 15. Microstructure of virgin 20-volume-percent B4C-reinforced Al MMC. 

Figure 16. Microstructure of virgin 20-volume-percent Al2O3-reinforced Al MMC. 
14

samples have been listed in table 5. Questionable or inconsistent data are marked with a 

question mark and ndl indicates that no diffraction line was present for that phase. Note that 

compared to the corresponding diffraction peaks from the monolithic control sample, the 

intensities from the aluminum-matrix peaks are reduced and, in general, are inversely 

proportional to the volume-percent of the SiC phase present in that MMC. The corresponding 

increase in all the SiC peak intensities is, again, generally proportional to the amount of SiC 

phase present in each MMC. Typical diffraction scans for virgin samples of the two other 

20-volume-percent MMC variants with B4C and Al2O3 reinforcements are shown in figures 6 

and 7. The phase-analysis software identified the primary phases in the unexposed substrate as 

aluminum and boron carbide or aluminum and corundum. The Miller indices and intensities of 

the corresponding prominent peaks for these MMCs have been listed in tables 6 and 7, 

respectively. 

Table 3. Gravimetric measurements (cleaned specimens). 

Specimen 

Initial 

Weight 

(g) 

Final 

Weight 

(g) 

Change in 

Weight 

(g) 

Average 

Change 

(g) 

Corrosion Rate 

(gmd) 

6061 Al (monolithic) 21.4056 

21.4343 

21.4039 

21.4319 

0.0017 

0.0024 

0.0021 0.00097261 

6092 Al 20-volumepercent black SiC 47.7314 

47.7186 

47.6657 

47.6562 

0.0657 

0.0624 

0.0641 0.01234878 

6092 Al 50-volumepercent black SiC 49.1076 

49.1702 

48.6768 

48.8441 

0.4308 

0.3261 

0.3785 0.07176491 

6092 Al 50-volumepercent green SiC 48.5586 48.3209 0.2377 0.2377 0.04739349 

6092 Al 20-volumepercent B4C 

44.8217 

44.9342 

44.4436 

44.6625 

0.3781 

0.2717 

0.3249 0.06161030 

6092 Al 20-volumepercent Al2O347.9893 

48.0114 

47.8255 

47.8330 

0.1638 

0.1784 

0.1711 0.03469962 

Table 4. Gravimetric measurements (uncleaned specimens). 

Specimen 

Initial 

Weight 

(g) 

Final 

Weight 

(g) 

Change in 

Weight 

(g) 

Surface Area 

(cm2

) 

Weight Change 

/Unit Area 

(g/cm2) 

6061 Al (monolithic) 21.4323 21.4368 0.0045 51.613 0.000087 

6092 Al 20-volumepercent black SiC 47.7455 47.8077 0.0622 137.245 0.000453 

6092 Al 50-volumepercent black SiC 49.2496 49.8476 0.5980 137.987 0.004333 

6092 Al 50-volumepercent green SiC 47.3706 47.6614 0.2908 131.342 0.002214 

6092 Al 20-volumepercent B4C 44.7391 45.0951 0.3560 137.028 0.002598 

6092 Al 20-volumepercent Al2O3

48.0078 48.1658 0.1580 130.080 0.001215 
15

Table 5. XRD peak intensities for virgin and exposed 6061 aluminum and Al-SiC MMC specimens. 

Bayerite Phase SiC Phase Al Phase 

Specimen 

Months 

Exposed Face 

(020) hkl, 

20.3° 2θ

(111) hkl, 

27.8° 2θ

(100) hkl, 

34.1° 2θ

(002) hkl, 

35.7° 2θ

(111) hkl, 

38.5° 2θ

(200) hkl, 

44.7° 2θ

(220) h

65° 2

Front Ndl Ndl Ndl Ndl 15751 7476 366

0 Back — — — — — — — 

Front Ndl Ndl Ndl Ndl 13515 3439 7613 

6 Back Ndl Ndl Ndl Ndl 15686 7161 4882 

Front Ndl Ndl Ndl Ndl 14042 6166 5183 

6061 Al 

(monolithic) 

12 Back Ndl Ndl Ndl Ndl 11131 8001 ? 4729 

Front Ndl Ndl 888 2245 9228 4446 187

0 Back Ndl Ndl 873 2193 9170 5040 185

Front Ndl Ndl 847 ? 2340 ? 9790 ? 3106 1694 

6092 Al 20- 

volume-percent 

black SiC 12 Back Ndl Ndl 775 2410 ? 9983 ? 3440 161

Front Ndl Ndl 2085 6354 7157 2687 119

0 Back — — — — — — — 

Front 37 16 1838 5707 6028 2420 1102 

6 Back 95 50 2276 ? 6557 ? 5258 2106 935 

Front 772 192 1147 3069 1923 792 519 

6092 Al 50- 

volume-percent 

black SiC 

12 Back 128 28 2088 ? 5627 5378 2003 103

Front Ndl Ndl 2351 6674 6248 2800 1232 

0 Back — — — — — — — 

Front 169 41 1756 4830 4422 1984 800 

6092 Al 50- 

volume-percent 

green SiC 12 Back 67 19 2689 ? 6538 5420 2400 1084 

Notes: Ndl = no diffraction line was present. 

? = questionable or inconsistent data. 
16

Table 6. XRD peak intensities for virgin and exposed Al-B4C MMC specimens. 

Bayerite Phase B4C Phase Al Phase 

Specimen 

Months 

Exposed Face 

(020) hkl, 

20.3° 2θ

(111) hkl, 

27.8° 2θ

(012) hkl, 

23.5° 2θ

(104) hkl, 

35° 2θ

(111) hkl, 

38.5° 2θ

(200) hkl, 

44.7° 2θ

(220) h

65° 2

Front Ndl Ndl 326 378 13949 6408 2852 

0 Back Ndl Ndl 318 388 12990 6354 254

Front 293 74 175 234 8604 4048 200

6092 Al 20-

volume percent 

B4C 12 Back 155 16 231 292 11080 5891 231

Note: Ndl = no diffraction line was present. 

Table 7. XRD peak intensities for virgin and exposed Al-Al2O3 MMC specimens. 

Bayerite Phase Al2O3 Al Phase 

Specimen 

Months 

Exposed Face 

(020) hkl, 

20.3° 2θ

(111) hkl, 

27.8° 2θ

(104) hkl, 

35.1° 2θ

(113) hkl, 

43.3° 2θ

(111) hkl, 

38.5° 2θ

(200) hkl, 

44.7° 2θ

(220) h

65° 2

Front Ndl Ndl 1348 1414 12129 5144 226

0 Back Ndl Ndl 1336 1437 12108 5413 231

Front 17 Ndl 1194 1267 9788 4800 2164 

6092 Al 20- 

volume-percent 

Al2O3 12 Back 206 27 973 1166 7539 3648 1782 

Note: Ndl = no diffraction line was present. 
17

4.3.2 Diffraction Scans for Exposed Samples With Substrate and Corrosion Product 

Phase 

Typical diffraction scans from the front faces of the 12-month-exposed samples of the black and 

green SiC MMC variants are shown in figures 8 and 9, respectively. The phase-analysis 

software again identified the primary phases from the front and back faces of the exposed 

substrate as Al and SiC. Compared to the unexposed samples, the corresponding prominent 

peaks reappear but have attenuated intensities (see table 5). Typically, the attenuation of peak 

intensities from the back face is less than the front face. This observation can intuitively be 

interpreted (at least for the SiC-reinforced MMCs) that the corrosion film on the front face is 

thicker than that on the back face. Note the presence of two broad corrosion-product diffraction 

peaks labeled (020) Bayerite and (111) Bayerite that have been detected from the surfaces of the 

50-volume-percent black and green SiC MMCs but are absent from the monolithic and 

20-volume-percent SiC samples. Bayerite is a hydrated form of aluminum oxide with a density 

of ~3 g/cm3

. It is remarkable that these Bayerite peak intensities are greater on the sample front 

face than on the back face by a factor of 3. Consistent with gravimetric data and the aluminum 

peak-intensity attenuation observations, it is not surprising that the intensities of the 50-volumepercent black-SiC Bayerite peaks are substantially greater than the 50-volume-percent green-SiC 

Bayerite peaks on either of the corresponding front or back surfaces. One can speculate that the 

appearance of the crystalline (020) and (111) Bayerite peaks represent some form of amorphousto-crystalline transformation of the original Bayerite corrosion film, especially as the surface 

layer grows in thickness. 

Typical diffraction scans from the front faces of 12-month-exposed samples of two 20-volumepercent MMC variants with B4C and Al2O3 reinforcements are shown in figures 10 and 11. The 

phase-analysis software again identified the primary phases as either aluminum and boron 

carbide or aluminum and corundum. The Miller indices and intensities of the corresponding 

prominent peaks for these MMCs from the front and back surfaces are listed in tables 6 and 7, 

respectively. Compared to the unexposed samples, the corresponding prominent peaks reappear 

but have attenuated intensities. For the boron-carbide MMC (and in common with the SiC MMC 

data), the attenuation of peak intensities from the back face being less than the front face and the 

presence of more intense Bayerite peaks diffracting from the front face should be noted. This 

combination of results leads to the interpretation that the corrosion film on the front face is much 

thicker than on the back face. 

Counterintuitive results were detected for the alumina MMC. The attenuation of peak intensities 

from the front face being less than the back face, as well as the presence of more intense Bayerite 

peaks diffracting from the back face (see table 7), leads to the conflicting conclusion that the 

corrosion film on the back surface is thicker than on the front face, unlike the other sample 

results. Perhaps for the exposed alumina MMCs, solar irradiation might have impeded the 

corrosion process on the top surface; clearly, irradiation, climate, and humidity factors were 
18

unchanged from the other (silicon-carbide- and boron-carbide-reinforced) MMC samples, since 

all of them were exposed for identical periods on the same rack. 

4.3.3 Phase Identification of the Corrosion Film on Exposed Substrates 

The original conceptual corrosion model for these environmentally exposed Al-MMC samples 

was that a semicontinuous film of corrosion product formed and chronologically grew in 

thickness over the substrate. The most likely oxidation product was some form of amorphous 

hydrated aluminum oxide since, in general, crystalline peaks of hydrated aluminum oxide were 

not detected by XRD on samples with environmental exposures of up to 6 months. In addition to 

the visually observed formation of a corrosion-product film on these samples, the XRD 

characterization results indicated that a substantial attenuation of the diffraction peaks from the 

primary aluminum and the crystalline reinforcement phase occurred and that there was a general 

increase of the overall low-angle background intensity values (arbitrarily measured at 23° 2θ), 

compared to the virgin counterpart samples, but it was not possible to determine the specific 

composition of this generic aluminum-oxide corrosion product. However, the increase in 

magnitude of this relative background intensity with exposure duration did track with the 

gravimetric data (see table 3), providing another indirect measure that the thickness of this 

amorphous corrosion layer was increasing with time. Fortunately, after 1 year, the detection of 

semicrystalline (020) and (111) Bayerite diffraction peaks for some MMC samples gave 

evidence that the originally formed amorphous phase was transforming into its crystalline state 

that was presumed to be of the same composition. Identifying Bayerite as the likely corrosionfilm product will be used subsequently in corrosion-film-thickness calculations. 

5. Discussion – Determining Corrosion Layer Thickness From X-ray Peak 

Attenuation Measurements 

5.1 Derivation of Thickness Determining Formula 

In order to quantify the effect of the overlying corrosion layer on attenuating diffracted beam 

intensities, an equation to determine such thicknesses (t) will be derived and adapted to the 

relevant diffractometer geometry. These calculations can be made by using the ratio of the 

diffracted peak (hkl) intensity of the virgin (v) sample ID(hkl)v to that of an exposed (e) sample 

ID(hkl)e, along with handbook physical constants. 

The first derivation is based on the generic linear attenuation absorption model (12). When xrays with initial intensity Io pass through a slab of absorbing material of thickness x, the resulting 

attenuation leads to a less-intense transmitted beam intensity Ix, as illustrated in figure 17. The 

relationship between the initial and the transmitted intensity is expressed in equation 1. 

 Ix = Ioexp[–(u/r)rx]. (1) 
19

Figure 17. Linear x-ray-intensity 

absorption model. 

The attenuation of the transmitted beam intensity, in addition to having a negative exponential 

relationship with the distance traversed in the absorbing layer, also is affected by the mass 

absorption coefficient (u/r) and the density (r) of that absorbing layer. Based on experimental 

insight for this x-ray characterization study that a corrosion layer formed on aluminum and AlMMCs substrates, the value chosen for the alumina (or corundum) mass absorption coefficient 

was 26.71 cm2/g and the density was nominally 3 g/cm3 (for Bayerite alumina with three waters 

of hydration; note that a range of values exist that are a function of the number of waters of 

hydration). These constants should approximately match those for hydrated alumina and were 

used in calculating nominal film thicknesses (even if not exact, they certainly provided a ranking 

order of calculated thicknesses as a function of time and sample characteristics). Thus, even if 

other values are subsequently chosen, only some recalculation will be required to adjust the 

absolute values; this will certainly not affect the generally observed trends that provide 

significant insight for this study. 

These absorption calculations need to be adapted for the appropriate diffractometer geometry 

(12) used to record diffracted peak intensities, as indicated in figure 18. Note the following 

linear and geometrical relationships: 

• thickness of the continuous alumina film = t 

• Bragg angle for (hkl) peak = 2θ

• total x-ray absorption path length in film = x = 2y = 2t/sinθ. 

For the usual diffractometer geometry, the intensity diffracted by peak (hkl), ID(hkl), can be 

determined using equation 1 by inserting the total absorbing path length, x, 

 ID(hkl) = Ioexp[–(u/r)rx] = AIoexp[–(u/r)r2t/sinθ] , (2) 

where A = diffraction intensity correction factor for each (hkl) peak. 
20

Figure 18. Corrosion film x-ray-intensity 

absorption model adapted to 

diffraction geometry. 

For unexposed (virgin, v) samples where there is no corrosion overlayer (t = 0), equation 2 

becomes 

 ID(hkl)v = A(hkl)Io . (3) 

After outdoor exposure (e), an oxide film of thickness t, forms, so that equation 2 now becomes 

 ID(hkl)e = A(hkl)Ioexp[–(u/r)r 2t/sinθ]. (4) 

The corrosion product thickness t, is solved for from the ratio of equations 3 and 4, 

 t = ln[ID(hkl)v/ID(hkl)e]sinθ/[2(u/r)r]. (5) 

5.2 Calculated Corrosion-Product Thickness 

Equation 5 was used to calculate the corrosion-product thicknesses for all the samples exposed 

for 1 year. The results for major diffraction peaks from the aluminum matrix and the respective 

reinforcement phases have been listed in tables 8–10. 

Caveats for these measurements and calculations (that depend explicitly on the ratio of a series 

of single (hkl) peak intensity values but taken at different times) need to be outlined to explain a 

certain amount of variability/uncertainty apparent in these tables. First, it should be noted that 

the standard deviation for the accuracy of this data can be as high as 50%, especially when peak 

intensities are low, resulting in small, statistically undesirable peak-to-background ratios (12). 

This was the systematic case for certain weakly diffracting reinforcing phases, where only one or 

two major peak-intensity values were used for calculating thicknesses. Additionally, equipmentrelated factors can also produce small systematic or random drifts in incident radiation intensity, 

due to equipment and power supply variations; these in turn affect the exact magnitude of the 

measured diffracted peak intensities during an individual diffraction scan. Then there can be 

local variations in sample microstructure and corrosion rate variables (with kinetics that vary by 
21

Table 8. Corrosion product thickness as a function of XRD peak intensity attenuations for virgin and exposed 6061 aluminum and A

specimens. 

 Peak Intensity Thickness of Corrosion Product 

(μm) 

Bayerite Phase SiC Phase Al Phase 

Specimen 

Months 

Exposed Face 

(020) hkl, 

20.3° 2θ

(111) hkl, 

27.8° 2θ

(100) hkl, 

34.1° 2θ

(002) hkl, 

35.7° 2θ

(111) hkl, 

38.5° 2θ

(200) hkl, 

44.7° 2θ

(220) h

65° 2

Front Ndl Ndl Ndl Ndl — — — 

0 Back — — — — — — — 

Front Ndl Ndl Ndl Ndl 2.4 4.5 ? 

6061 Al 

(monolithic) 12 Back Ndl Ndl Ndl Ndl 7.1 ? ? 

Front Ndl Ndl — — — — — 

0 Back Ndl Ndl — — — — — 

Front Ndl Ndl ? ? ? 10.2 3.2 

6092 Al 20- 

volume-percent 

black SiC 12 Back Ndl Ndl ? ? ? 7.8 4.8 

Front Ndl Ndl — — — — — 

0 Back — — — — — — — 

Front 772 192 ? 13.9 27 28.8 27.8 

6092 Al 50-

volume-percent 

black SiC 12 Back 128 28 ? 2.3 5.9 6.9 4.7 

Front Ndl Ndl — — — — — 

0 Back — — — — — — — 

Front 169 41 ? 6.2 7.1 8.1 14.5 

6092 Al 50-

volume-percent 

green SiC 12 Back 67 19 ? 0.39 2.9 2.8 4.3 

Notes: Ndl = no diffraction line was present. 

? = questionable or inconsistent data. 

Table 9. Corrosion product thickness as a function of XRD peak intensity attenuations for virgin and exposed Al-B4C MMC specim

Peak Intensity Thickness of Corrosion Product 

(μm) 

Bayerite Phase B4C Phase Al Phase 

Specimen 

Months 

Exposed Face 

(020) hkl, 

20.3° 2θ

(111) hkl, 

27.8° 2θ

(012) hkl, 

23.5° 2θ

(104) hkl, 

35° 2θ

(111) hkl, 

38.5° 2θ

(200) hkl, 

44.7° 2θ

(220) h

65° 2

Front Ndl Ndl — — — — — 

0 Back Ndl Ndl — — — — — 

Front 293 74 7.8 9.2 9.2 10.7 9.9 

6092 Al 20- 

volume-percent 

B4C 12 Back 155 16 4.2 5.1 4 1.9 5.2 

Note: Ndl = no diffraction line was present. 
22

Table 10. Corrosion product thickness as a function of XRD peak intensity attenuations for virgin and exposed Al-Al2O3 MMC spe

Peak Intensity Thickness of Corrosion Product 

(μm) 

Bayerite Phase Al2O3 Phase Al Phase 

Specimen 

Months 

Exposed Face 

(020) hkl, 

20.3° 2θ

(111) hkl, 

27.8° 2θ

(104) hkl, 

35.1° 2θ

(113) hkl, 

43.3° 2θ

(111) hkl, 

38.5° 2θ

(200) hkl, 

44.7° 2θ

(220) h

65° 2

Front Ndl Ndl — — — — — 

0 Back Ndl Ndl — — — — — 

Front 17 Ndl 2.2 2.7 4.4 2.2 1.9 

6092 Al 20- 

volume-percent 

Al2O3 12 Back 206 27 6.1 4.6 9.7 8.7 8.4 

Note: Ndl = no diffraction line was present. 

Table 11. Comparative values (from averaged diffraction peak results) of corrosion product thickness after 12 months 

outdoor exposure. 

Specimen 

Weight Gain

/Unit Area 

(g/cm2)

Face 

Nominal 

Value 

Over SiC 

Particles 

(μm)

Nominal 

Value Over 

B4C Particles 

(μm) 

Nominal 

Value Over 

Al2O3

Particles 

(μm) 

No

Val

Al 

6061 Al (monolithic) Front Ndl Ndl Ndl 

0.000087 Back Ndl Ndl Ndl 

6092 Al 20-volume-percent Front ? Ndl Ndl 

black SiC 0.000453 Back ? Ndl Ndl 

6092 Al 50-volume-percent Front 13.9 ? Ndl Ndl 

black SiC 0.004333 Back 2.3 Ndl Ndl 

6092 Al 50-volume-percent Front 6.2 Ndl Ndl 

green SiC 0.002214 Back 0.4 ? Ndl Ndl 

6092 Al 20-volume-percent Front Ndl 8.5 Ndl 

B4C 0.002598 Back Ndl 4.7 Ndl 

6092 Al 20-volume-percent Front Ndl Ndl 2.5 

Al2O3 0.001215 Back Ndl Ndl 5.4 

Notes: Ndl = no diffraction line was present. 

? = questionable or inconsistent data. 
23

a factor of 2 for samples in the same environment not being unusual) that further complicate the 

experimental data. 

Despite these caveats, in general, the thickness values track consistently with the gravimetrically 

determined weight-change values as summarized in table 11, where averaged diffraction peak 

results from the aluminum matrix and the reinforcement phases after a 1-year exposure are 

presented. Except for the 20-volume-percent Al2O3 MMC with a thicker corrosion product layer 

on the back face, the reinforced Al-MMC samples had a thicker corrosion layer on the front, 

upward facing surface, with by far the thickest being the 28-μm layer present on the 

50-volume-percent black SiC MMC, followed by three others in the 7–10-μm range. The 

corresponding back-face thicknesses ranged from 3 to 6 μm and were not consistent with the 

gravimetric trends. It was also interesting to note that the front-face corrosion-product thickness 

over the silicon-carbide particles was about 1/2 of that over the aluminum matrix, while the 

corrosion-product thicknesses over the reinforcing boron carbide and alumina particles were 

slightly less but similar to that over the aluminum matrix. (Further surface examination will be 

required to determine whether there is some continuity of the corrosion layer over the 

reinforcement particles or whether, if there is no local coverage, it is an artifact produced by the 

absorption of x-rays passing at a diffraction angle θ through the corrosion product growing above 

the adjacent aluminum-matrix phase). For the 20-volume-percent reinforcement phase series, 

the boron-carbide MMC had a thicker front-face corrosion layer than the silicon-carbide MMC 

(both based on gravimetric and film-thickness results). The alumina-reinforced MMC with the 

intermediate gravimetric result and the contrary presence of a thinner front face and a thicker 

back-face corrosion layer will clearly need to be investigated further. 

6. Conclusions 

6.1 Outdoor-Exposure Corrosion Rates 

Although this report covers observations from only a limited set of monolithic and Al-MMC 

samples subjected to 1 year of atmospheric exposure at a single (but climatologically the wettest) 

HCL location, some trends are clearly visible from the gravimetric corrosion data. For 

comparable exposure times, all of these MMCs have a corrosion rate that is at least an order of 

magnitude greater than a similar monolithic aluminum alloy. The bulk corrosion rate of MMCs 

reinforced with black SiC generally increases with an increase in volume fraction of the 

reinforcement. This increase in corrosion rate appears to be (more than linearly) proportional to 

the volume fraction of the SiC (where the gravimetric rate for 50-volume-percent SiC MMC is at 

least 5× greater than the 20-volume-percent SiC MMC even though the 50-volume-percent SiC 

sample presented 1/3 less aluminum-matrix-phase surface area to react). Also, the corrosion rate 

for the 50-volume-percent black-SiC MMC was about twice that of the 50-volume-percent 

green-SiC MMC that is of higher purity and higher resistivity. This would be expected because 

of galvanic action if the black SiC supports cathodic currents. However, the 50-volume-percent 
24

green SiC had a higher corrosion rate than the 20-volume-percent black-SiC MMC, indicating 

that reinforcement phase content was also significant. 

Of the three 20-volume-percent MMCs with different reinforcement species, the B4C MMC 

generally corroded at a higher rate than those reinforced with either Al2O3 (with an intermediate 

rate) or SiC (with the lowest rate). Also, the 20-volume-percent B4C MMC with significantly 

less reinforcement phase had a higher corrosion rate than the 50-volume-percent green SiC. This 

trend is also likely due in part to the resistivity of the reinforcements, since B4C generally has 

low resistivity, SiC has wide fluctuations in resistivity depending on purity, and Al2O3 is an 

insulator. Although there is a trend for the corrosion rate to increase with increased 

reinforcement content, there is now strong evidence that the type of reinforcing phase can 

strongly influence the atmospheric corrosion rate of that MMC. Thus, those MMCs with higher 

resistivity reinforcement particles tend to have comparably lower corrosion rates. 

These outdoor-exposure tests generally support the hypothesis that corrosion is related to the 

conductivity and the volume fraction of the reinforcement specie. Corrosion rates increased as 

the content of black SiC was increased. For the same volume fractions, the corrosion rates were 

lower in MMCs reinforced with high-purity green SiC than for those with black SiC. Corrosion 

rates were higher for MMCs reinforced with B4C than they were for MMCs reinforced with 

equal amounts of either SiC or Al2O3. 

6.2 Characterizing the Corrosion-Product Layers 

Experimental XRD data for virgin and exposed samples of the control coupon and the five MMC 

variants yielded quantitative and qualitative characterization of the atmospheric corrosion 

products that formed on these samples during their 1-year outdoor exposure. Further analysis 

using intensity ratios of the virgin and exposed samples provided semiquantitative measures of 

the corrosion-product thickness. 

For the exposed samples, the relative intensities of the aluminum and the reinforcement 

diffraction peaks decrease significantly relative to those from their comparable virgin samples. 

The attenuation of the peak-intensity values was found to be somewhat proportional to the 

thickness of corrosion product that formed over the original substrate. Typically, for all but the 

exposed 20-volume-percent alumina MMC sample, the observed attenuation of the peakintensity values was greater for XRD scans obtained from the front (upward facing) surfaces than 

from the back surfaces of each sample, indicating that the front surface had a thicker corrosion 

product. By far, the largest corrosion-layer thickness (28 μm) was calculated for the front 

surface of the 50-volume-percent black-SiC MMC, and this was consistent with the gravimetric 

data—three of the other four reinforced MMCs were in the 9–10-μm range. Nearly all of the 

back surfaces had 3–6-μm thicknesses, with the exception of the anomalous 20-volume-percent 

alumina MMC sample with 3- and 9-μm front and back thicknesses, respectively. 
25

For the XRD scans from the monolithic control and the 20-volume-percent black-SiC MMC 

samples exposed for 1-year, peak-intensity attenuations resulted in peaks that were nominally 

80% of those from virgin samples, with no evidence of a crystalline-hydrated aluminum oxidephase. Thus, it was concluded that the overlying corrosion product that caused the observed 

peak-intensity attenuations was due to the presence of a semicontinuous hydrated aluminum 

oxide layer that also increased the low-angle background intensities. But since no crystallinehydrated aluminum-oxide diffraction peaks were detected, the attenuation was attributed to an 

overlying amorphous Bayerite corrosion-product layer. 

Most of the rest of the exposed samples’ XRD scans had greater peak-intensity attenuations 

consistent with the presence of thicker corrosion-product layers. In addition, all of these XRD 

scans (including the anomalous 20-volume-percent alumina MMC sample) had two other distinct 

general features that were metrified (see tables 8–10): the background levels of XRD scans 

were elevated (the arbitrary values reported were for the background intensity at 2θ = 23o

, 

chosen because no overlapping crystalline peaks appeared in any XRD scan), and the presence of 

semicrystalline alumina namely, (020) Bayerite and (111) Bayerite diffraction peaks that 

appeared as a crystalline peaks (with measurable peak intensities that proved to be a good 

metric) emerging from an amorphous hump. These metrics qualitatively tracked well with and 

were inversely proportional to the attenuation of the substrate phase(s) diffraction peak 

intensities, thus, indirectly substantiating the corrosion-product-thickness calculation results. 

7. Summary 

In general, this corrosion-product characterization study provided important insights into 

procedures for measuring Al MMC corrosion. It is intuitively obvious that corrosion phenomena 

and kinetics on the front and back faces of outdoor-corrosion specimens should be different, and 

this study has quantified these differences. In most cases, the thickness of the corrosion-product 

layer on the front surface exceeds that on the back surface since environmental effects such as 

solar irradiation and/or the extended presence of water/electrolyte films should be greater on the 

upward facing sample face. However, the caveat is that bulk gravimetric measurements of 

corrosion (rates) only represent the weighted average of the phenomena occurring on the upward 

facing and back surfaces. Thus, care in interpreting any gravimetric corrosion measurement 

results is recommended. 

The case for the anomalous reversal of thicknesses on front and back surfaces of the 20-volumepercent alumina MMC sample deserves further study to confirm whether the results are 

repeatable. If this phenomenon is real, fundamental studies should be undertaken to discover 

what physical phenomena in the reinforcement phase can impede and/or accelerate corrosion 

kinetics. One can speculate that for this specific MMC, the presence or absence of solar 

irradiation may affect the properties of certain forms of crystalline Al2O3 that, in turn, may alter 

the kinetics and/or mechanism of Al-MMC corrosion. 
26

For applications that consider utilizing Al-MMCs components for their superior mechanical 

properties, appropriate regard should be taken for the lowered environmental durability of these 

materials relative to monolithic aluminum alloys. This limitation can be compensated for by 

designing in greater thicknesses for that component or by using suitable corrosion-mitigating 

coatings or other surface treatments.
27

8. References 

1. Ceradyne, Inc. Home Page. http://www.ceradyne.com (accessed April 2002). 

2. Ichinose, N. Introduction to Fine Ceramics; Wiley: New York, NY, 1987; pp 50–52. 

3. Bolz, R. E.; Tuve, G. L. CRC Handbook of Tables for Applied Engineering Science, 

2nd Ed.; CRC Press: Boca Raton, FL, 1973; pp 262–264. 

4. Goodfellow Corp. Metals and Materials Catalog; Oakdale, PA, 1991–1992. 

5. DWA Aluminum Composites Home Page. http://www.dwa-dra.com (accessed May 2003). 

6. Goodfellow Corp. Technical Data Sheet. http://www.goodfellow.com (accessed May 

2003). 

7. Hihara, L. H. Corrosion of Metal Matrix Composites. Corrosion: Materials, Environments, 

and Industries; American Society of Metals International: Materials Park, OH, 2005. 

8. Hihara, L. H. Metal-Matrix Composites. In Manual on Corrosion Tests and Standards: 

Application and Interpretation, 2nd Ed.; American Society for Testing and Materials 

International: West Conshohocken, PA, 2005. 

9. Wylie, R. G. Humidity and Moisture. Wexler, A., Ed.; Reinhold Publishing Corp.: New 

York, NY, 1964; p 507. 

10. Hongbo, D.; Hihara, L. H. Localized Corrosion Currents and pH Profile over B4C, SiC, and 

Al2O3 Reinforced 6092 Aluminum Composites in 0.5M Na2SO4 Solution. Journal of the 

Electrochemical Society 2005, 152, (4). 

11. ISO 8407. Corrosion of Metals and Alloys – Removal of Corrosion Products from 

Corrosion Test Specimens 1991. 

12. Cullity, B. D. Elements of X-Ray Diffraction, 2nd Ed.; Addison-Wesley: Reading, MA, 

1978.
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 BLDG 1 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 SFAE AMO MAS SETI 

 T C LIVECCHIA 

 BLDG 354 SOUTH 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 AMSRD AAR AEM L 

 M YOUNG 

 BLDG 65 SOUTH 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 AMSRD AAR AEM C 

 D DEMELLA 

 BLDG 61 SOUTH 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 AMSRD AAR AEM 

 S CHICO 

 BLDG 65 SOUTH 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 SFAE AMO MAS LC 

 D RIGOGLIOSO 

 BLDG 354 M829E3 IPT 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 AMSRD AAR AEM L 

 P DONADIA 

 BLDG 65 SOUTH 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 AMSTA AR CCH B 

 K HENRY 

 BLDG 95 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 AMSRD AAR AEM L 

 F DONLON 

 BLDG 65 SOUTH 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 PM MAS 

 SFAE AMO MAS 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 SFAE AMO MAS LC 

 P VALENTI 

 BLDG 354 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 AMSRD AAR AEM L 

 R SAYER 

 BLDG 65 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 SFAE AMO MAS LC 

 F CHANG 

 BLDG 354 

 PICATINNY ARSENAL NJ 

 07806-5000 
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 1 PM ARMS 

 AMSRD AAR EMB 

 J BRESCIA 

 BLDG 1 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 PM MAS 

 SFAE AMO MAS 

 CHIEF ENGINEER 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 PM MAS 

 SFAE AMO MAS PS 

 PICATINNY ARSENAL NJ 

 07806-5000 

 2 PM MAS 

 SFAE AMO MAS LC 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 COMMANDER 

 US ARMY TACOM 

 AMSTA SF 

 WARREN MI 48397-5000 

 1 COMMANDER 

 US ARMY TACOM 

 PM COMBAT SYSTEMS 

 SFAE GCS CS 

 6501 ELEVEN MILE RD 

 WARREN MI 48397-5000 

 2 OFC OF NAVAL RSRCH 

 J CHRISTODOULOU 

 D SHIFLER 

 ONR CODE 332 

 800 N QUINCY ST 

 ARLINGTON VA 22217-5600 

 1 COMMANDER 

 US ARMY TACOM 

 PM SURVIVABLE SYSTEMS 

 SFAE GCSS W GSI H 

 M RYZYI 

 6501 ELEVEN MILE RD 

 WARREN MI 48397-5000 

 1 COMMANDER 

 US ARMY TACOM 

 CHIEF ABRAMS TESTING 

 SFAE GCSS W AB QT 

 J MORAN 

 6501 ELEVEN MILE RD 

 WARREN MI 48397-5000 

 1 COMMANDER 

 WATERVLIET ARSENAL 

 SMCWV QAE Q 

 B VANINA 

 BLDG 44 

 WATERVLIET NY 12189-4050 

 2 SFSJM CDL 

 HQ US ARMY JNT MUNITIONS CMND 

 AMSIO SMT 

 R CRAWFORD 

 W HARRIS 

 1 ROCK ISLAND ARSENAL 

 ROCK ISLAND IL 61299-6000 

 2 COMMANDER 

 US ARMY AMCOM 

 AVIATION APPLIED TECH DIR 

 J SCHUCK 

 FORT EUSTIS VA 23604-5577 

 1 NSWC 

 DAHLGREN DIV CODE G06 

 DAHLGREN VA 22448 

 2 US ARMY CORPS OF ENGR 

 CERD C 

 T LIU 

 CEW ET 

 T TAN 

 20 MASSACHUSETTS AVE NW 

 WASHINGTON DC 20314 

 1 US ARMY TARDEC 

 AMSRD TAR R 

 D TEMPLETON 

 6501 E 11 MILE RD MS 263 

 WARREN MI 48397-5000 
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 3 USA SBCCOM 

 MATERIAL SCIENCE TEAM 

 AMSSB RSS 

 J HERBERT 

 M SENNETT 

 L-A BARKHOUSE 

 KANSAS ST 

 NATICK MA 01760-5057 

 2 COMMANDER 

 US ARMY RDECOM 

 AMSTA TR R 

 J BENNETT 

 D HANSEN 

 MS 271 

 WARREN MI 48397-5000 

 1 COMMANDER 

 US ARMY RDECOM 

 AMSTA TR D 

 D OSTBERG 

 MS 263 

 WARREN MI 48397-5000 

 1 USA SBCCOM PM SOLDIER SPT 

 AMSSB PM RSS A 

 J CONNORS 

 KANSAS ST 

 NATICK MA 01760-5057 

 7 BENET LABS 

 AMSTA AR CCB 

 R FISCELLA 

 G SPENCER 

 R HASENBEIN 

 AMSTA CCB R 

 S SOPOK 

 E HYLAND 

 D CRAYON 

 R DILLON 

 WATERVLIET NY 12189-4050 

 1 NSWC 

 TECH LIBRARY CODE B60 

 17320 DAHLGREN RD 

 DAHLGREN VA 22448 

 1 NSWC 

 CRANE DIV 

 M JOHNSON CODE 20H4 

 LOUISVILLE KY 40214-5245 

 2 NSWC 

 U SORATHIA 

 C WILLIAMS CODE 6551 

 9500 MACARTHUR BLVD 

 WEST BETHESDA MD 20817 

 2 COMMANDER 

 NSWC 

 CARDEROCK DIV 

 R PETERSON CODE 2020 

 M CRITCHFIELD CODE 1730 

 BETHESDA MD 20084 

 1 NAVAL SEA SYSTEMS CMND 

 D LIESE 

 1333 ISAAC HULL AVE SE 1100 

 WASHINGTON DC 20376-1100 

 7 DIRECTOR 

 US ARMY NGIC 

 D LEITER MS 404 

 M HOLTUS MS 301 

 M WOLFE MS 307 

 S MINGLEDORF MS 504 

 J GASTON MS 301 

 W GSTATTENBAUER MS 304 

 J CRIDER MS 306 

 2055 BOULDERS RD 

 CHARLOTTESVILLE VA 

 22911-8318 

 1 AFRL MLBC 

 2941 P ST RM 136 

 WRIGHT PATTERSON AFB OH 

 45433-7750 

 1 DIRECTOR 

 LOS ALAMOS NATL LAB 

 F L ADDESSIO T 3 MS 5000 

 PO BOX 1633 

 LOS ALAMOS NM 87545 

 1 NSWC 

 CARDEROCK DIV 

 R CRANE CODE 6553 

 9500 MACARTHUR BLVD 

 WEST BETHESDA MD 20817-5700 

 1 AFRL MLMP 

 R THOMSON 

 2977 HOBSON WAY 

 BLDG 653 RM 215 

 WRIGHT PATTERSON AFB OH 

 45433-7739 
NO. OF NO. OF 

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 6 US ARMY RSRCH OFC 

 H EVERITT 

 J PRATER 

 G ANDERSON 

 D STEPP 

 D KISEROW 

 D SKATRUD 

 PO BOX 12211 

 RESEARCH TRIANGLE PARK NC 

 27709-2211 

 7 US ARMY SBCCOM 

 SOLDIER SYSTEMS CTR 

 BALLISTICS TEAM 

 J WARD 

 W ZUKAS 

 P CUNNIFF 

 J SONG 

 MARINE CORPS TEAM 

 J MACKIEWICZ 

 AMSSB RCP SS 

 W NYKVIST 

 S BEAUDOIN 

 KANSAS ST 

 NATICK MA 01760-5019 

 8 NSWC 

 J FRANCIS CODE G30 

 D WILSON CODE G32 

 R D COOPER CODE G32 

 J FRAYSSE CODE G33 

 E ROWE CODE G33 

 T DURAN CODE G33 

 L DE SIMONE CODE G33 

 R HUBBARD CODE G33 

 DAHLGREN VA 22448 

 2 AFRL MLMP 

 F ABRAMS 

 J BROWN 

 2977 HOBSON WAY 

 BLDG 653 RM 215 

 WRIGHT PATTERSON AFB OH 

 45433-7739 

 1 DIRECTOR 

 LLNL 

 STEVE DETERESA 

 PO BOX 808 

 LIVERMORE CA 94550 

 1 DIRECTOR 

 LLNL 

 L-125 FRANK MAGNESS 

 PO BOX 808 

 LIVERMORE CA 94550 

 1 DIRECTOR 

 LLNL 

 L-020 MILTON FINGER 

 PO BOX 808 

 LIVERMORE CA 94550 

 1 DIRECTOR 

 LLNL 

 L-099 MIKE MURPHY 

 PO BOX 808 

 LIVERMORE CA 94550 

 1 AFRL MLS OL 

 L COULTER 

 5851 F AVE 

 BLDG 849 RM AD1A 

 HILL AFB UT 84056-5713 

 1 OSD 

 JOINT CCD TEST FORCE 

 OSD JCCD 

 R WILLIAMS 

 3909 HALLS FERRY RD 

 VICKSBURG MS 29180-6199 

 2 DARPA 

 S WAX 

 L CHRISTODOULOU 

 3701 N FAIRFAX DR 

 ARLINGTON VA 22203-1714 

 1 OAK RIDGE NATL LAB 

 R M DAVIS 

 PO BOX 2008 

 OAK RIDGE TN 37831-6195 

 1 OAK RIDGE NATL LAB 

 C EBERLE MS 8048 

 PO BOX 2008 

 OAK RIDGE TN 37831 

 3 NIST 

 J CHIN MS 8621 

 J MARTIN MS 8621 

 D DUTHINH MS 8611 

 100 BUREAU DR 

 GAITHERSBURG MD 20899 
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 1 OAK RIDGE NATL LAB 

 C D WARREN MS 8039 

 PO BOX 2008 

 OAK RIDGE TN 37831 

 1 HYDROGEOLOGIC INC 

 SERDP ESTCP SPT OFC 

 S WALSH 

 1155 HERNDON PKWY STE 900 

 HERNDON VA 20170 

 3 DIRECTOR 

 SANDIA NATL LABS 

 APPLIED MECHS DEPT 

 MS 9042 

 J HANDROCK 

 Y R KAN 

 J LAUFFER 

 PO BOX 969 

 LIVERMORE CA 94551-0969 

 2 NASA LANGLEY RSRCH CTR 

 AMSRD ARL VT 

 F BARTLETT JR MS 266 

 G FARLEY MS 266 

 HAMPTON VA 23681-0001 

 1 FHWA 

 E MUNLEY 

 6300 GEORGETOWN PIKE 

 MCLEAN VA 22101 

 1 USDOT FEDERAL RAILROAD 

 M FATEH RDV 31 

 WASHINGTON DC 20590 

 1 CYTEC FIBERITE 

 R DUNNE 

 1300 REVOLUTION ST 

 HAVRE DE GRACE MD 21078 

 1 DIRECTOR 

 NGIC 

 IANG TMT 

 2055 BOULDERS RD 

 CHARLOTTESVILLE VA 

 22911-8318 

 1 3TEX CORP 

 A BOGDANOVICH 

 109 MACKENAN DR 

 CARY NC 27511 

 1 DIRECTOR 

 DEFNS INTLLGNC AGCY 

 TA 5 

 K CRELLING 

 WASHINGTON DC 20310 

 1 COMPOSITE MATERIALS INC 

 D SHORTT 

 19105 63 AVE NE 

 PO BOX 25 

 ARLINGTON WA 98223 

 1 JPS GLASS 

 L CARTER 

 PO BOX 260 

 SLATER RD 

 SLATER SC 29683 

 1 COMPOSITE MATERIALS INC 

 R HOLLAND 

 11 JEWEL CT 

 ORINDA CA 94563 

 1 SIMULA 

 R HUYETT 

 10016 S 51ST ST 

 PHOENIX AZ 85044 

 2 PROTECTION MATERIALS INC 

 M MILLER 

 F CRILLEY 

 14000 NW 58 CT 

 MIAMI LAKES FL 33014 

 1 ROM DEV CORP 

 R O MEARA 

 136 SWINEBURNE ROW 

 BRICK MARKET PLACE 

 NEWPORT RI 02840 

 1 TEXTRON SYSTEMS 

 M TREASURE 

 1449 MIDDLESEX ST 

 LOWELL MA 01851 

 1 O GARA HESS & EISENHARDT 

 M GILLESPIE 

 9113 LESAINT DR 

 FAIRFIELD OH 45014 

 1 CONNEAUGHT INDUSTRIES INC 

 J SANTOS 

 PO BOX 1425 

 COVENTRY RI 02816 
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 1 ARMTEC DEFENSE PRODUCTS 

 S DYER 

 85 901 AVE 53 

 PO BOX 848 

 COACHELLA CA 92236 

 3 PACIFIC NORTHWEST LAB 

 M SMITH 

 G VAN ARSDALE 

 R SHIPPELL 

 PO BOX 999 

 RICHLAND WA 99352 

 1 ALLIANT TECHSYSTEMS INC 

 4700 NATHAN LN N 

 PLYMOUTH MN 55442-2512 

 1 APPLIED COMPOSITES 

 W GRISCH 

 333 NORTH SIXTH ST 

 ST CHARLES IL 60174 

 1 CUSTOM ANALYTICAL 

 ENG SYS INC 

 A ALEXANDER 

 13000 TENSOR LANE NE 

 FLINTSTONE MD 21530 

 1 AAI CORP 

 DR N B MCNELLIS 

 PO BOX 126 

 HUNT VALLEY MD 21030-0126 

 1 PROJECTILE TECHLGY INC 

 515 GILES ST 

 HAVRE DE GRACE MD 21078 

 3 ALLIANT TECHSYSTEMS INC 

 J CONDON 

 E LYNAM 

 J GERHARD 

 WV01 16 STATE RT 956 

 PO BOX 210 

 ROCKET CENTER WV 

 26726-0210 

 1 PRATT & WHITNEY 

 C WATSON 

 400 MAIN ST MS 114 37 

 EAST HARTFORD CT 06108 

 3 NORTHROP GRUMMAN 

 B IRWIN 

 K EVANS 

 D EWART 

 BLDG 160 DEPT 3700 

 1100 W HOLLYVALE ST 

 AZUSA CA 91701 

 1 BRIGS COMPANY 

 J BACKOFEN 

 2668 PETERBOROUGH ST 

 HERNDON VA 22071-2443 

 1 ZERNOW TECHL SERVICES 

 L ZERNOW 

 425 W BONITA AVE STE 208 

 SAN DIMAS CA 91773 

 2 GENERAL DYNAMICS OTS 

 FLINCHBAUGH DIV 

 K LINDE 

 T LYNCH 

 PO BOX 127 

 RED LION PA 17356 

 1 GKN WESTLAND AEROSPACE 

 D OLDS 

 450 MURDOCK AVE 

 MERIDEN CT 06450-8324 

 1 AEROSPACE CORP 

 G HAWKINS M4 945 

 2350 E EL SEGUNDO BLVD 

 EL SEGUNDO CA 90245 

 2 CYTEC FIBERITE 

 M LIN 

 W WEB 

 1440 N KRAEMER BLVD 

 ANAHEIM CA 92806 

 2 UDLP 

 G THOMAS 

 M MACLEAN 

 PO BOX 58123 

 SANTA CLARA CA 95052 
NO. OF NO. OF 

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 5 SIKORSKY AIRCRAFT 

 G JACARUSO 

 T CARSTENSAN 

 B KAY 

 S GARBO MS S330A 

 J ADELMANN 

 6900 MAIN ST 

 PO BOX 9729 

 STRATFORD CT 06497-9729 

 2 UDLP 

 R BRYNSVOLD 

 P JANKE MS 170 

 4800 E RIVER RD 

 MINNEAPOLIS MN 55421-1498 

 1 LOCKHEED MARTIN 

 SKUNK WORKS 

 D FORTNEY 

 1011 LOCKHEED WAY 

 PALMDALE CA 93599-2502 

 1 NORTHRUP GRUMMAN CORP 

 ELECTRONIC SENSORS 

 & SYSTEMS DIV 

 E SCHOCH MS V 16 

 1745A W NURSERY RD 

 LINTHICUM MD 21090 

 1 GDLS DIV 

 D BARTLE 

 PO BOX 1901 

 WARREN MI 48090 

 1 GDLS 

 M PASIK 

 PO BOX 2074 

 WARREN MI 48090-2074 

 1 GDLS 

 MUSKEGON OPER 

 M SOIMAR 

 76 GETTY ST 

 MUSKEGON MI 49442 

 1 GENERAL DYNAMICS 

 AMPHIBIOUS SYS 

 SURVIVABILITY LEAD 

 G WALKER 

 991 ANNAPOLIS WAY 

 WOODBRIDGE VA 22191 

 5 INST FOR ADVANCED 

 TECH 

 H FAIR 

 I MCNAB 

 P SULLIVAN 

 S BLESS 

 C PERSAD 

 3925 W BRAKER LN 

 AUSTIN TX 78759-5316 

 1 ARROW TECH ASSOC 

 1233 SHELBURNE RD STE D8 

 SOUTH BURLINGTON VT 

 05403-7700 

 1 SAIC 

 G CHRYSSOMALLIS 

 8500 NORMANDALE LAKE BLVD 

 STE 1610 

 BLOOMINGTON MN 55437-3828 

 1 UCLA MANE DEPT ENGR IV 

 H T HAHN 

 LOS ANGELES CA 90024-1597 

 1 UMASS LOWELL 

 PLASTICS DEPT 

 N SCHOTT 

 1 UNIVERSITY AVE 

 LOWELL MA 01854 

 1 IIT RSRCH CTR 

 D ROSE 

 201 MILL ST 

 ROME NY 13440-6916 

 1 MICHIGAN STATE UNIV 

 MSM DEPT 

 R AVERILL 

 3515 EB 

 EAST LANSING MI 48824-1226 

 1 PENN STATE UNIV 

 R S ENGEL 

 245 HAMMOND BLDG 

 UNIVERSITY PARK PA 16801 

 1 PENN STATE UNIV 

 C BAKIS 

 212 EARTH ENGR 

 SCIENCES BLDG 

 UNIVERSITY PARK PA 16802 
NO. OF NO. OF 

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 1 PURDUE UNIV 

 SCHOOL OF AERO & ASTRO 

 C T SUN 

 W LAFAYETTE IN 47907-1282 

 1 UNIV OF MAINE 

 ADV STR & COMP LAB 

 R LOPEZ ANIDO 

 5793 AEWC BLDG 

 ORONO ME 04469-5793 

 1 JOHNS HOPKINS UNIV 

 APPLIED PHYSICS LAB 

 P WIENHOLD 

 11100 JOHNS HOPKINS RD 

 LAUREL MD 20723-6099 

 1 UNIV OF DAYTON 

 J M WHITNEY 

 COLLEGE PARK AVE 

 DAYTON OH 45469-0240 

 2 UNIV OF DELAWARE 

 CTR FOR COMPOSITE MTRLS 

 J GILLESPIE 

 S ADVANI 

 201 SPENCER LAB 

 NEWARK DE 19716 

 1 MISSISSIPPI STATE UNIV 

 DEPT OF AEROSPACE ENGRG 

 A J VIZZINI 

 MISSISSIPPI STATE MS 39762 

 1 SOUTHWEST RSRCH INST 

 ENGR & MATL SCIENCES DIV 

 J RIEGEL 

 6220 CULEBRA RD 

 PO DRAWER 28510 

 SAN ANTONIO TX 78228-0510 

 1 DREXEL UNIV 

 A S D WANG 

 3141 CHESTNUT ST 

 PHILADELPHIA PA 19104 

 1 DEPT OF MTRLS 

 SCIENCE & ENGRG 

 UNIV OF ILLINOIS 

 AT URBANA CHAMPAIGN 

 J ECONOMY 

 1304 W GREEN ST 115B 

 URBANA IL 61801 

 3 UNIV OF TEXAS AT AUSTIN 

 CTR FOR ELECTROMECHANICS 

 J PRICE 

 A WALLS 

 J KITZMILLER 

 10100 BURNET RD 

 AUSTIN TX 78758-4497 

 3 DIRECTOR 

 US ARMY RSRCH LAB 

 AMSRD ARL WM MB 

 A FRYDMAN 

 2800 POWDER MILL RD 

 ADELPHI MD 20783-1197 

 1 DEPARTMENT HEAD 

 US MILITARY ACADEMY 

 K NYGREN 

 CIVIL & MECH ENGRG DEPT 

 WEST POINT NY 10996-1792 

 1 DIRECTOR 

 US MILITARY ACADEMY 

 D BOETTNER 

 MECH ENGRG DIV 

 WEST POINT NY 10996-1792 

 1 US ARMY ARDEC 

 AMSRD AAR ATD 

 B MACHAK 

 BLDG 1 

 PICATINNY ARSENAL NJ 

 07806-5000 

 1 US ARMY ARDEC 

 AMSRD AAR AEP E 

 D CARLUCCI 

 BLDG 94 

 PICATINNY ARSENAL NJ 

 07806-5000 

 10 HAWAII CORROSION LAB 

 2540 DOLE ST 

 HOMES HALL RM 302 

 G HAWTHORN 

 L HIHARA 

 HONOLULU HI 96822 
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 2 NORTH DAKOTA STATE UNIV 

 DEPT OF COATINGS & POLYMERIC 

 MTRLS 

 G P BIERWAGEN 

 V J GELLING 

 1222 9TH ST S 

 FARGO ND 58105-5516 

 2 OHIO STATE UNIV 

 DEPT OF MTRLS SCIENCE & ENGRG 

 G S FRANKEL 

 R BUCHEIT 

 2041 COLLEGE RD WATTS HALL 

 COLUMBUS OH 43210-1179 

 1 UNIV OF CALIFORNIA BERKELEY 

 COLLEGE OF ENGRG 

 F M DOYLE 

 308 MCLAUGHLIN HALL NO 1702 

 BERKELEY CA 94720-1700 

 1 RENSSELEAR POLYTECHNIC INST 

 DEPT OF MTRLS ENGRG 

 D J DUQUETTE 

 TROY NY 12818 

 1 THE BOEING COMPANY 

 DIRECTOR OF MATRLS & PROCESS 

 TECHLGY 

 D CHONG 

 2553 134TH AVE SE 

 BELLEVUE WA 98005 

 1 UNIV OF VIRGINIA 

 CTR FOR ELECTROCHEMICAL 

 SCIENCE & ENGRG 

 DEPT OF MTRLS SCIENCE & ENGRG 

 J R SCULLY 

 PO BOX 400745 

 116 ENGRGS WAY 

 CHARLOTTESVILLE VA 22904-4745 

 1 UNIV OF MICHIGAN 

 DEPT OF MTRLS SCIENCE & ENGRG 

 G S WAS 

 H H DOW BLDG 

 2300 HAYWARD ST 

 ANN ARBOR MI 48109-2136 

 1 PENNSYLVANIA STATE UNIV 

 B SHAW 

 212 EES BLDG 

 UNIV PARK PA 16870 

 1 EXPONENT INC 

 MECHS & MTRLS DEPT 

 R M LATANISION 

 21 STRATHMORE RD 

 NATICK MA 01760 

 1 NATIONAL MATERIALS ADVISORY 

 BOARD 

 M H MOLONEY 

 500 FIFTH ST NW 

 MS WS938 

 WASHINGTON DC 20001 

 1 USMC 

 MAINTENANCE CTR ALBANY 

 S ALLEN 

 28008 NEWCOMB RD 

 ALBANY GA 31705 

 2 AIR FORCE CORROSION 

 PREVENTION & CNTRL OFC 

 K ANDREWS 

 MAJ R REED 

 325 RICHARD RAY BLVD BLDG 165 

 ROBINS AFB GA 31098-1639 

 3 US ARMY TACOM TARDEC RDECOM 

 AMSTA TR E1 MEPS 1267 

 I C HANDSY 

 J KOVANDA 

 A BAZIARI 

 6501 E 11 MILE RD BLDG 200A 

 WARREN MI 48397-7738 

 5 US ARMY RDECOM 

 AMSRD AMR PS AM 

 S F CARR 

 R A HERRON 

 K BHANSALI 

 M KANE 

 A P STEELE 

 BLDG 7103 

 REDSTONE ARSENAL AL 35898 

 1 NASA CORROSION TECHLGY 

 J CURRAN 

 MS ASRC 20 

 KENNEDY SPACE CENTER FL 32899 
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 1 OUSD (A T & L) 

 OFC OF CORROSION POLICY & 

 OVERSIGHT 

 D J DUNMIRE 

 2001 N BEAUREGARD ST STE 210 

 ALEXANDRIA VA 22311 

 1 OUSD FOR SCIENCE AND TECHLGY 

 ODDR&E(S &T) 

 MATRLS & STRUCTURES OFC 

 L E SLOTER 

 1777 N KENT ST STE 9030 

 ARLINGTON VA 22209-2110 

 3 CONCURRENT TECHNOLOGIES CORP 

 L GINTERT 

 R MASON 

 M SINGLETON 

 7935 114 TH AVE 

 LARGO FL 33773 

 3 US ARMY ERDC 

 CONSTRUCTION ENGRG RSRCH LAB 

 V HOCK 

 A KUMAR 

 L D STEPHENSON 

 PO BOX 9005 

 CHAMPAIGN IL 61826-9005 

 6 US ARMY ARDEC 

 ARMY CORROSION OFC 

 AMSRD AAR AEE P 

 R ZANOWICZ 

 J P THEIS 

 D SKELTON 

 D SCHMIDT 

 J ZUNINO 

 E MCCARTHY 

 BLDG 60 

 PICATINNY ARSENAL NJ 07806-5000 

 1 COMMANDER 

 NAVSEAAIR 

 CORROSION RSRCH & ENGRG BR 

 R HAYS 

 NSWCCD CODE 613 

 9500 MACARTHUR BLVD 

 WEST BETHESDA MD 20817-5700 

 2 COMMANDER 

 NAVAIR 

 MTRLS COATINGS & CORROSION 

 C MATZDORF 

 S SPADAFORA 

 AIR 4 3 4 BLDG 2188 

 PATUXENT RIVER MD 20670 

 2 BATTELLE MEMORIAL INST 

 NATIONAL SECURITY DIV 

 MATERIALS AND ENGRG GROUP 

 W ABBOTT 

 B HINDIN 

 505 KING AVE 

 COLUMBUS OH 43201-2693 

ABERDEEN PROVING GROUND

 1 US ARMY ATC 

 CSTE DTC AT AD I 

 W C FRAZER 

 400 COLLERAN RD 

 APG MD 21005-5059 

 102 DIR USARL 

 AMSRD ARL CI 

 AMSRD ARL O AP EG FI 

 M ADAMSON 

 AMSRD ARL WM 

 J SMITH 

 AMSRD ARL WM B 

 CHIEF 

 M ZOLTOSKI 

 AMSRD ARL WM BA 

 T KOGLER 

 D LYON 

 AMSRD ARL WM BC 

 J NEWILL 

 P PLOSTINS 

 AMSRD ARL WM BD 

 P CONROY 

 B FORCH 

 M LEADORE 

 C LEVERITT 

 R LIEB 

 R PESCE-RODRIGUEZ 

 B RICE 

 A ZIELINSKI 

 AMSRD ARL WM BF 

 S WILKERSON 

 AMSRD ARL WM M 

 J MCCAULEY 

 S MCKNIGHT 

 J BEATTY 
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 AMSRD ARL WM MA 

 M VANLANDINGHAM 

 L GHIORSE 

 AMSRD ARL WM MB 

 J BENDER 

 T BOGETTI 

 J BROWN 

 L BURTON 

 K CHO 

 W DRYSDALE 

 R EMERSON 

 D GRAY 

 D HOPKINS 

 R KASTE 

 L KECSKES 

 H MAUPIN 

 B POWERS 

 D SNOHA (10 CPS) 

 J SOUTH 

 M STAKER 

 J SWAB 

 J TZENG 

 AMSRD ARL WM MC 

 R ADLER (10 CPS) 

 K CHESONIS 

 J ESCARSEGA 

 B HART 

 T JESSEN 

 J KELLEY 

 M MAHER 

 C M MILLER 

 F PIERCE 

 B PLACZANKIS 

 P SMITH 

 W SPURGEON 

 S K YOUNG 

 AMSRD ARL WM MD 

 B CHEESEMAN 

 E CHIN 

 P DEHMER 

 R DOOLEY 

 G GAZONAS 

 S GHIORSE 

 J LASALVIA 

 J MONTGOMERY 

 J SANDS 

 D SPAGNUOLO 

 S WALSH 

 AMSRD ARL WM RP 

 J BORNSTEIN 

 E RIGAS 

 C SHOEMAKER 

 AMSRD ARL WM SG 

 R CARTER 

 AMSRD ARL WM T 

 P BAKER 

 AMSRD ARL WM TA 

 W BRUCHEY 

 M BURKINS 

 B GOOCH 

 T HAVEL 

 C HOPPEL 

 E HORWATH 

 J RUNYEON 

 S SCHOENFELD 

 AMSRD ARL WM TC 

 R COATES 

 AMSRD ARL WM TD 

 D DANDEKAR 

 M RAFTENBERG 

 T WEERASOORIYA 

 AMSRD ARL WM TE 

 CHIEF 

 J POWELL
NO. OF 

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 1 ROYAL INSTITUTE OF TECHNOLOGY 

 C LEYGRAF 

 KTH DROTTNING VAG 51 

 SE 100 STOCKHOLM SWEDEN
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