END-OF-YEAR-REPORT

MICROMECHANICAL PROPERTIES OF BERYLLIUM

AND OTHER INSTRUMENT MATERIALS

by

Bruce W. Christ and Robert S. Polvani

NBS Fracture and Deformation Division

Robert J. Hocken

NBS Mechanical Processes Division

National Bureau of Standards

Washington, D.C. 20234

Report To: Office of Naval Research

495 Summer Street

Boston, Massachusetts 02210

Contract Moniter: Dr. Frank Gardner

l

October 1978
f
MICROMECHANICAL PROPERTIES OF BERYLLIUM

AND OTHER INSTRUMENT MATERIALS

This research program was initiated on October 1, 1977. it i s sponsored

by the Office of Naval Research. The objective of the program is to evaluate

and understand the micromechanical properties of beryllium and other

instrument materials for use in gyroscopes, so that dimensional instability

can be improved. Improved dimensional stability is expected to lessen the

need to periodically align gyroscopes in service. Drift in alignment has been

attributed in part to mass shifts of 10

6 inches in critical components of

gyroscopes.

This program has two major thrusts. One is to measure micromechanicai

-7

properties at strains of less than 10 . Properties of interest include

microyield stress, microcreep rate, and microstrain hardening. The other major

thrust is to measure micromechanicai properties at strains of less than 10 "

.

This program is carried out in cooperation with materials engineers and gyroscope

designers on the staff of the C. S. Draper Laboratory, Cambridge, Mass.

This report consists of two major parts.

Part A - Micromechanicai properties of instrument grade beryllium.

(description of the materials problem, instrumentation to make strain

-7

measurements in the range of 10 , and initial results.)

_ g

i Part B - 10 creep measurement system (introduction, the algorithm,

environmental chamber, cell proper, interferometer, summary.)
.

••
PART A

MICROMECHANICAL PROPERTIES OF

INSTRUMENT GRADE BERYLLIUM

A description of the materials problem and instrumentation

-7

to make strain measurements of 10 and upwards.

Initial results

MICROMECHANICAL PROPERTIES OF

INSTRUMENT-GRADE BERYLLIUM

by

Bruce W. Christ and Robert S. Polvani

1 1. Beryllium in Gyroscopes

Various grades of beryllium have found application in components of gyroscopes.

Beryllium is attractive for this purpose because of its low density, high strengthweight ratio, high stiffness* and very high thermal conductivity. Gyroscopes in

service require periodic realignment (sometimes as often as once a month) to

correct for drift due to various causes, including dimensional instability of

beryllium components. The current state-of-the-art in gyroscope design is based

on a net mass shift in critical components, such as, wheels of about 10 ^ inches.

This mass shift is characteristic of beryllium components machined from typical

commercial production lots of instrument-grade beryllium. Improved dimensional

stability of the beryllium will pave the way for future advances in the design

_ g of gyroscopes. For example, mass shift stability of 10 inches is sought for

the fourth-generation gyroscopes now being designed.

This research program has two goals. One is to develop a data base on the

microcreep rates of instrument-grade beryllium for use by gyroscope designers.

The other is to develop fundamental understanding of the causes of dimensional

instability in instrument-grade beryllium through correlations between measurements

of microplastic behavior and microstructural observations. Microplastic

properties to be measured include microcreep rates, microyield stresses, and

zero- load dimensional changes. Microstructural observations will be made using

optical microscopy (phase-contrast mode) , transmission electron microscopy,

scanning electron microscopy, and electron microprobe techniques.
II. Progress to Date

This research program was initiated on October 1, 1977. A uniaxial tensile

strain measuring system for reliable and accurate measurements in the range of

10

1 inches and upwards is now operational. Microcreep rates are being measured

at stresses from 1,000 to 15,000 psi at 144 HMD. 018 °F (62.2 +0.01°C) in an

environmentally-stable chamber. This temperature was selected to simulate the

environmental conditions in which a gyroscope's wheel operates. Temperatures of

critical components of an operating gyroscope range from 125-150°F (51. 7-65. 5°C)

.

An apparatus with the environmental and electronic stability required for

— 8

measurements in the 10 inch range has been designed and is partially-constructed.

A literature review on the microplastic properties of beryllium has been completed.

This review includes a survey of the microyield stresses for production lots of

instrument grade beryllium manufactured during the last two years. Some of the

survey results appear in Part y of this report.

-7

III. Testing System for Measuring 10 Strain

Figure 1 shows a testing system capable of measuring displacements below the

micro- inch range. The heart of this system is an extensometer utilizing

parallel-plate capacitors, which is described below. The extensometer fastens to

the cylindrical test specimen via machined ribs. Figure 2. The specimen is

installed in a creep frame of conventional manufacture. Dead load is applied via a

lever-and knife-edge linkage through ball-end joints on the specimen. The creep

frame is mounted on a concrete pedestal to minimize building vibrations. In

operation, a foam insulating cabinet surrounds the specimen and ball-end joints

to provide finely- tuned environmental control. Almost all of the electronic

equipment for measurement of displacement, temperature, and load is placed on a

standard relay rack, as shown in Figure 1. The entire system is located in a

remote basement room with good temperature and humidity control.

2
The extensometer has been described in detail elsewhere. It consists of

three independent parallel plate capacitors arrayed at 120° to one another about

the specimen circumference. The output of this device is linear with displacement

3 through use of appropriate circuitry. In its present state of refinement, the

_ 0

extensometer has an operating resolution of about 4 x 10 inches.

The average displacement determined from the independent strain probes

represents the displacement along the axial centerline of the test specimen. This

4 conclusion is arrived at from geometric analysis. Consequently, all axial strains

are calculated from the average displacement. Bending strains can be calculated by

comparing the average strain with the strain determined at each strain probe.

Bending arises from misalignment.

Alignment is an important consideration in microcreep measurements. Good

alignment is promoted by careful machining of the specimen and testing system

components, and by thoughtful design of the load train. This subject has been

reviewed thoroughly by Christ and Swanson.^ Because misalignment cannot be

completely eliminated in the best of testing systems, it has been suggested

that misalignment characteristic of microstrain measurements be represented by

the tangent of the angle between the tensile axis and the normal to the bend

5 -5

plane. Typical numbers for the present equipment range between 10 radians

-4

(very good alignment) to 10 radians (moderately good alignment)

.

Two techniques were used to calibrate the extensometer. First, a fringecounting laser interferometer was used as an absolute standard for measuring

length changes. The calibration constant determined using this technique was

0.0352 x 10 ^ inches per dial division on the decade transformer of the bridge

circuit. A second technique for calibration was to calculate the displacement

of an elastically-deformed beryllium sample from a handbook value of Young’s

6 — 0 modulus, 42.4 x 10 psi. The calibration constant was 0.03 x 10 inches per

dial division. These two calibration constants agree well with one another.

3
The microstrain data reported in Figures 3-5 were calculated using a calibration

— 8

constant of 3.5 x 10 inches per dial division.

Temperature control to about 0.018°F (0.01°C) is needed to make meaningful

-7

displacement measurements in the 10 inch range. Using the heat from light

bulbs, temperature in the environmental chamber is controlled at 144°F (62.2°C)

with a standard deviation of 0.018°F (+0.01°C). Successful runs have been made

for an accummulated time of 1200 hours. Temperature was measured using a single

thermistor mounted on the specimen just below the gage section.

IV. Initial Test Results

Initial results obtained with the testing system serve two purposes. First,

they provide a demonstration of the testing system capabilities. Secondly, they

provide a preview of some important features of the microcreep behavior of

instrument grade beryllium.

These initial results were obtained on a single specimen of the type shown

in Figure 2. Test temperature was 144 +0.018°f (62.2 -K).01°C). The specimen

* was stress relieved after machining with the following treatment :

o Heat slowly (at <100°F per hour) to 1450°

F

o Dwell at 1450° F for 1 hour to allow recovery

o Cool slowly (at <100°F per hour) to room temperature

Figures 3-5 show initial microstrain results from dead-weight loading of this

specimen. Several sequential loadings are indicated in the upper half of Figure 3.

Once loaded, the specimen was held at stress for at least one week. Between loading

the specimen was completely unloaded. Some refinements were made to the testing

system during the three loading cycles in the first 400 hours, in order to improve

the quality of the data. About 5 microinches per inch (hereafter, "microstrain"

* This treatment is the standard practice followed at the Charles Stark Draper

laboratory, Inc., Cambridge, Massachusetts.

4
will be used to signify "microinches per inch") accummulated during these three

loading cycles, as shown in Figure 4. The cummulative plastic strain for all

loading cycles is reported in Figure 4. Typical microcreep curves at 5,000 and

1,000 psi are shown in Figure 5.

These initial results show that the testing system operates according to

~8

design expectations. Displacement resolution is about 4 x 10 inches.

Temperature control is held to about 0.018°F (0.01°C), allowing for routine

-7

displacement measurements from 1 x 10 inches upwards. The system has good

alignment

.

Some interesting aspects of the microcreep behavior of instrument grade

beryllium show up in these initial results.

o Figures 3, 5. Measurable microcreep shows up at stresses less than the

nominal microyield strength (hereafter "MYS") of 8.6 Ksi reported by

-8

the manufacturer. A typical microcreep rate is 1 x 10 per hour,

i.e., 1 micro-inch in 100 hours.

o Figures 3, 5. Microcreep is linear with time, at least up to 140 hours.

The expected parabolic response might show up with longer times at stress,

o Figure 3. Microstrain hardening reduces, the microcreep rate substantially.

The amount of microstrain in a sequentially-loaded specimen does not

increase in proportion to increasing stress, apparently due to microstrain

exhaustion

.

o Figure 4. The cummulative plastic strain from successive loadings, including

stresses above the MYS, is less than 20 micro-strain.

V. Analysis of Manufacturers' Microyield Strength (MYS) Data

For lack of a better method, gyroscope designers estimate microcreep behavior

from measurements of MYS. The (unproven) assumption is that the higher the MYS,

the better the microcreep resistance should be. One of our long-term objectives

is to assist designers by evaluating this assumption by looking for a correlation

between MYS and microcreep resistance. As a starting point, we have solicited MYS

5
data from manufacturers. MYS data going back for 2 years on commercial production

lots of instrument-grade beryllium have been obtained and analyzed. Results are

shown in Figure 6. The following observations can be made:

Figure 6a - Manufacturer A

o Over the two-year time interval, MYS ranged from 8,000-14,000 psi

o MYS and scatter-band width tended to increase in the more recent

production lots.

o Within a given lot, there is a noticible variation of MYS from one

location to another within a pressing. Statistical analysis is being

carried out to formally evaluate this point,

o There appears to be an increase in the MYS by applying stress relief

and thermal cycling treatments.

Figure 6b - Manufacturer B

o Over the two-year time interval, MYS ranged between 8,000 and 14,500 psi.

o MYS and scatter-band width tended to increase in the more recent

production lots.

o Within a given lot, there is a noticible variation of MYS from one

location to another within a pressing. Statistical analysis is being

carried out to formally evaluate this point.

VI. Future Work

Eight test specimens of the type shown in Figure 2 are currently being machined

at the C.S. Draper Laboratory, Cambridge, Massachusetts. The machine shop there

has special facilities for handling toxic beryllium particles formed during

machining. Once in hand, these specimens will be tested in the system described

\ in Part III of this report. Testing will be carried out over a range of stresses

(1/2 MYS to 1 1/2 MYS) and temperatures (68 to 180°F) . The microcreep curves

developed will be of use to designers working with instrument grade beryllium.

Hopefully; a Zener-Hollomon plot can be developed to assist designers.
Micromechanisms of deformation will be looked into using transmission

electron microscopy and other techniques to probe the microstructure. The

dislocation content and configuration of undeformed and deformed specimens

will be examined and compared. An attempt will be made to identify the dislocation sources and barriers. It is expected that these results will serve

as a basis for future development of grades of beryllium exhibiting good

dimensional stability.

The following areas are suggested as supplements to the original program

if support can be found.

1. Establish several testing systems of the type described in Part III.

Multiple testing systems would increase the data rate substantially.

2. Measure microyield strength and microcreep resistance of several

grades of beryllium, to establish whether or not a correlation exists

between these two micromechanical properties.

3. Determine how various thermal cycling treatments affect micromechanical

properties and deformation mechanisms of instrument, grade beryllium.

’II. Acknowledgements

Mr. John McCarthy, C.S. Draper Laboratory, Inc., Cambridge, Mass, provided

helpful background information about beryllium in gyroscopes and has guided the

machining of damage free test specimens at the C.S. Draper Lab for the N.B.S.

testing program. Gyroscope design information has been provided by Mr. Fred Petrie,

'.S. Draper Laboratory, Inc. , Cambridge, Massachusetts and Mr. Fred Hallock,

Northrup Precision, Waltham, Massachusetts. Useful discussions about micromechanical

testing have been held with Mr. C. W. Marshall, Battelle-Columbus , Ohio and

Mr. A. Gross, Autonetics - Rockwell International Corporation, Anaheim, CA.
Mr. Roger Paquin, Perkin-Elmer , Stamford, Conn, has contributed interesting

discussions about precision applications of beryllium mirrors for optical

equipment. Mr. Fullerton-Batten of Kawecki-Berylco, Hazleton, Pennsylvania

provided some of the data appearing in Part V. Mr. William Becker and

Mr. J. Stonehouse, Brush-Wellman , Inc., also provided some of the data in

Part V.
Figure Captions

1. View of testing system used for microcreep measurements.

”7 — G

2. Microcreep test specimen for measurement in the 10 to 10 inch range.

3. Loading sequence and strain- time history for specimen Be-1.

4. Cummulative strain from sequential loadings of specimen Be-1.

5. Microcreep behavior of specimen Be-1 at 5,000 and 1,000 psi.

6a. MYS versus batch number from Manufacturer A.

6b. MYS versus batch number from Manufacturer B.

8
'

.
List of References

1. B.W. Christ and R.S. Polvani: A Review of the Micromechanical Properties

of Various Grades of Beryllium. N.B.S. Report in preparation.

2. B.W. Christ: Metallurgical Transactions £, No. 8, 1973, pp. 1961-1965.

3. F.K. Harris and R.D. Cutkosky: Instrument Society of America Journal 8,

No. 2, Feb. 1961, p. 63.

4. B.W. Christ, I.J. Feinberg and W. A. Willard: Appendix to "Pre-Macroyield

Behavior of Commercial Titanium Alloys Tested in Uniaxial Tension, Part I

-

Alignment Considerations and Plastic Microstrain of As-Ground, Mill-Annealed

Ti-6A1-4V." NBS Report 10640 to Materials Processing Branch, Naval Air

Systems Command, Dept, of Navy, Jan., 1972.

5. B.W. Christ and S.R. Swanson: ASTM Journal of Testing and Evaluation, 4,

No. 6, 1976, p. 405-417.

6a. J.W. Lyons: NASA Electronics Research Center Report C-110, 1970

Cambridge, Massachusetts.

6b. Aerospace Structural Metals Handbook, Code 5101, p. 17, June 1974.

Belfour Stolen Inc.

9
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PART B

—8

10 Creep Measurement System

Progress Report

August 1978

I. Introduction

II The Algorithm

III Environmental Chamber

IV Cell Proper

V Interferometer

VI Summary

—8

10 Creep System

1. INTRODUCTION

The goal of this portion of the project was to design, build,, and test

a system for the measurement of microcreep in Beryllium test specimens.

It was decided early in the project that the specimens were to be tested

around 45 °C, at loads up to 10,000 psi in tension. The time duration

of the tests was set at a minimum of three (3) months and the accuracy

~8

at 10 inches. These conditions lead to certain measurement constraints

that are summarized in Table 1. On the basis of these constraints several

design decisions were made. They are:

a) Laser interferometry was chosen as the length measurement sensor.

No other system known to us has the requisite stability over the required

time.

b) A modified atmosphere was chosen as the most cost effective way to

reduce the effect of refractive index changes on the interferometric

length scale.

c) A two stage conduction thermostat was chosen to obtain the required

thermal stability.

d) Dead weight loading was chosen as no other loading system known to

us provides the required stability.
2

e) A measurement algorithm was chosen to provide a consistent cross

check and give assurance that the apparatus was meeting design specifications.

As of the time of this report the design is completed and construction

well advanced. In the next 4 sections of this report we will describe

the algorithm, the enclosure design, the sample containers, and the

interferometer.

II. The Algorithm

In any measurement system the measurement algorithm is predicated by

the most stringent restriction to be placed on the measurement to be made.

In this instance, two restrictions combined to provide a very difficult

measurement problem. Specifically, the combination of high accuracy

—8 1 (10 inches) and long time (>3 months) dominates all other considerations.

In any algorithm two conditions must be met. First the measurements

should provide data of accuracy sufficient for the intended use and

secondly, there must be enough cross checking to insure that the measurement

system is functioning to the required degree of accuracy. In order that

these conditions be met, in spite of the two restrictions previously

mentioned, we have designed the experiment around a 6/2 time corrected

measurement sequence. In such a sequence there is one “master", one

“check standard", and four "unknowns".
!

I

3

Ideally such a system should include temperature checking, instrument

I checking and sample checking. To meet these objectives we have decided

1 upon the following samples:

1)

A cervit block, nominally of 4 inches .in length which has an effective

expansion coefficient of 0.034 ppm/°C.

2)

A well aged gage block, again of 4 inches in length, which has a

coefficient of 11.5 ppm/°C, quite close to that of Beryllium.

The combination of samples 1 and 2 is intended to act as a "master" and

a "check standard". Since both materials are of high stability^^ we

can expect to get from 1, a check on the interferometry, and from the

differences between 1 and 2, a check on the temperature stability of the

system.

J111

All the other samples are Beryllium. They are:

3)

An unloaded Be sample from the same batch as the samples under load

and

(4,5 Be samples under loads of nominally 10,000 psi, 5000 psi and

2500 psi.
4

Sample 3 serves to access the long term dimensional stability of

Be, which is, to our knowledge, unknown. The other three samples are to

provide the necessary data to obtain the creep curve at a single temperature.

Table 2 shows the planned sample identification and the measurement

sequence for each time a measurement is made. The full details of the

algorithm design and the computer program to be used for data reduction

( 2 ) have been explained by Reeve. The principle, briefly outlined, is to

establish the process standard deviation by the repeated measurements,

to check for process control by testing the differences between the master

and check standard and to remove any operator bias by using pseudo random

sequencing

.

Ill . The Environmental Enclosure

\

In order to implement the algorithm described in Section II, It was

necessary to design an enclosure that would contain 6 samples in a controlled temperature and controlled atmosphere environment. Futhermore,

such an enclosure had to allow for dead weight loading and maintain the

samples precisely aligned for optical gaging.

Figures 1, 2, and 3 show the enclosure layout. The device consists

of a rigid base plate to provide structural strength, a two stage
5

conduction thermostat built around this base plate, and provision for

loading three of the six samples it can contain.

Two features of the design are of interest. First, its successful

operation requires five (5) thermal control systems (heater, sensor,

bridge and feedback loop). Two of these systems control the main cylindrical shells. The outer shell is to be controlled to +.01 degrees at a

temperature slightly below the nominal 45 °C. The inner shell is then

controlled only slightly above the outer shell to insure isothermal

conditions. Thermostats of this type have developed stabilities of +10

(3) pK over many months. The other three loops are to be used for

canceling the heat leaks necessitated by the load bearing rods that

emerge from the thermostat to the load frame. Matched thermistor pairs

will be used, one in the inner case and one on the rod, to sense and

correct for any temperature differences that arise. Figures 4 and 5

show the bridge circuit and feedback loop circuits to be used for these

control operations.

The other feature was necessitated by the requirement of atmospheric

control coupled with deadweight loading. In order to seal the device

yet still allow nearly frictionless motion of the load rods, new sealing

techniques had to be tried. At the stage where the rod passes through

the base plate, ferrofluidic seals have been incorporated to provide -

this seal.
6

At the time of this writing, the enclosure construction is nearing

completion and we expect to do the initial assembly before October 1, 1978.

IV. The Sample Cell

Because of the modular nature of the enclosure design each of the

samples required a special cell which is an integral part of the loading

mechanism. Figure 6 shows the layout of one of these sample containers.

It is designed to have two adjustments of sample angle with respect to

the loading mechanism. One of these is furnished through the enclosure

inner shell base plate. This adjusts the angle of the bottom grip, which

is constrained by a high quality linear bearing, with respect to the

loading member. The other adjustment alters the angle of the top grip

with respect to the bottom. This adjustment has a coarse control, screws,

which are used in initial alignment and a fine adjustment provided by

piezo stacks which will be electrically controlled in the measurement

process. Sample alignment to within +1 second of arc is expected.

V . The Interferometer

Initially it was thought by the authors that the interferometry could

be done with a simple Michelson configuration. This proved impossible
7 in prototype form due to errors caused by our inability to align

samples to the degree of angular reproducibility (M3. 01 arc sec) required

—8

to obtain 10 accuracy with this type of interferometer.

A second interferometer with the requisite insensitivity to angle

(4) was then built . It is diagrammed schematically in Figures 7 and 8.

Figure 7 shows it in a form that allows ready understanding of the principle

involved and Figure 8 the configuration as it will actually be used.

Briefly the device works as follows: a two frequency beam of

polarization encoded laser light is incident upon the beam splitter.

One frequency f

^ is reflected off the beam splitter, into a corner cube,

reflected from the beam splitter again and returned to the detector (at

\ the same angle as the incident angle). The other beam f^ passes through

the beam splitter and quarter wave plate and is reflected off the sample.

It returns through the quarter wave plate to the beam splitter but now,

because of the double passage through the quarter wave plate, is reflected

at the beam splitter interface and into the other cube corner. The cube

corner retroref lects it back to the plane reflector, preserving the angle,

so that it strikes the plane mirror at the same angle as it emerged after

the first reflection. It therefore comes off the mirror after this second

reflection at its original incident angle and returns towards the beam

splitter. Double passage through the quarter wave plate again has rotated

the polarization 90°, however, and the beam now passes out of the interfero-

/ i meter. The double reflection and retroref lector thus make this device

highly insensitive to angle (up to several degrees). Angular information
8

may easily be extracted, however, by a 45° rotation of the quarter wave

plate. This feature allows autocollimation of the reflection for sample

alignment within the +1 sec specified previously.

A prototype system like that shown in Figure 8 has been built and

tested and the final interferometer designed and built.

The electronics to be used for the phase detection of the heterodyne

beat notes between the two optical beams is shown in Figure 9. The

detector and most electronics (amps, phase meter, reference oscillator,

H. P. counter) have now been ordered but procurement delays have been

encountered. We expect initial testing of the final system to begin

sometime in November.

VI. Summary

We now believe that all the serious design problems for this system

have been overcome and expect to begin debugging of the final setup on

or about October 1. Data acquisition should commence three months from

that date. Additional expenditures of about $10-20 K in equipment are

anticipated, mostly for a dedicated laser and counter system.
Table 1 - Measurement Constraints

Precision

or Parameter Stability Accuracy Reason

Length

_8 +10 inches_8 +10 inches Design Specs

Time >10^ sec NA Design Specs

Predicated by 1 and 2

Temperature +.001 °C +.1 °C Thermal Expansion

Load +10“ 5 +1% Elastic Deformation

Atmosphere +0.01 mm (air) +0.01 mm Length Scale

Stability
Table 2 - Algorithm Design

A) Sample Specification

Number Identification

1

2

3

4

5

6

Cervit

Steel

Be ,o-10, 000 psi

Be, o=5 ,000 psi

Be, o=0

Be, o=2, 500 psi

B) Measurement Sequence - Single Measurement

Block # Order

12

3

4

5

2. 3. 2. 1.2. 4.

2

3.4.3. 1. 3.5.3

4. 5. 4. 1.4. 6.

4

5. 6. 5. 1.5. 2.

5

6. 2. 6. 1.6. 3.

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INTERFEROMETER ELECTRONICS
References

1) J. W. Berthold III, S. F. Jacobs, and Mary Norton, "The Incredible

Flowing Glass", Optical Sciences Center Newsletter, 9 , #3, Dec. 1975.

2) Charles P. Reeve, NBSIR, "The Calibration of Angle Blocks by

Intercomparison", to be published.

3) A. L. Sengers, R. J. Hocken, and J. V. Sengers, "Critical-Point

Universality and Fluids", Physics Today, .30, // 12, Dec. 1977.

4) J. N. Duties and G. B. Gordon, "A Two-Hundred-Foot Yardstick with

Graduations every Microinch", Hewlett-Packard Journal, August 1970.
M v j>

IS. DEPT. OF COMM.

liographic data

SHEET

1. PUBLICATION OR REPORT NO. 2. Gov’t Accession

No.

3. Recipient’s Accession No.

Ilk and subtitle

>-0F- YEAR-REPORT

.’ROMECHANICAL PROPERTIES OF BERYLLIUM AND OTHER INSTRUMENT

?E RIALS

5. Publication Date

6. Performing Organization Code

FHOR(S)

L Christ, R.S. Polvani and R.J. Hocken

8. Performing Organ. Report No.

(FORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

1

10. Projcct/Task/Work Unit No.

11. Contract/Grant No.

msoring Organization Name and Complete Address (Street, City, State, ZIP)

Eice of Naval Research

5 Summer Street

ston, Massachusetts 02210

itract Moniter: Dr. Frank Gardner

13. Type of Report & Period

Covered

END-OF-YEAR

14. Sponsoring Agency Code

PPLEMENTARY NOTES

| (STRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bliography or literature survey, mention it here.)

This research program was initiated on October 1, 1977. It is sponsored by

e Office of Naval Research. The objective of the program is to evaluate and

derstand the micromechanical properties of beryllium and other instrument

terials for use in gyroscopes, so that dimensional stability can be improved,

proved dimensional stability is expected to lessen the need to periodically

ign gyroscopes in service.

I

I 3 WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper

•is-.r; separata! by semicolons)

'rylliumj dimensional stability; gyroscope; instrument materials; microcreep;

icromechanical properties.

VAII. ABILITY

JJ/] Unlimited 19. SECURITY CLASS

(THIS REPORT)

21. NO. OF PAGES

For Official Distribution. Do Not Release to NTIS

UNCL ASSIFIED

Order From Sup. of Doc., U.S. Government Printing Office Washington, D.C. 20402. SD Cat. No. Cl 3

20. SECURITY CLASS

(THIS PAGE)

22. Price

Order From National Technical Information Service (NTIS!

Springfield, Virginia 2 2 I 5 1 UNCLASSIFIED

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