bluuebunny/crossref_metadata_2025 huggingface dataset:
Beneficial Effects of Boron Addition into γ-TiAl Alloys
Authors: Li Z.X. , Huang Xia , Qi L.C. , Cao Chun Xiao
Published: March 2009

The beneficial effects of boron addition on microstructure transformations and
mechanical properties of γ-TiAl alloys were investigated. Two growth mechanisms of boride (TiB2)
in γ-TiAl alloy were confirmed, the curved flaky borides are products of irregular eutectic reaction
growing coupled with matrix, while some faceted blocky borides in boron-rich alloy are primary
TiB2 phase growing directly in melt. The core of flaky TiB2 is ultra-fine B2 phase and there has an
orientation relationship [1210] TiB2//[001]B2, (1010) //(010)B2. In addition to the well-known
grain refinement effect, boron addition can suppress the formation of metastable feathery and
Widmastätten structure and broadens cooling-rate-range for the formation of fully lamellar structure,
consequently, it improves thermal stability of the lamellar structure and accordingly prolongs the
creep rupture life significantly. Another beneficial effect of boron addition is that boride can
restrain discontinuous coarsening on lamellar grain boundary by pinning action and accelerates
recrystallization of γ grain by introducing TiB2/matrix interfaces as nuclear sites during
homogeneous treatment at 1150°C. Therefore, compared with boron-free alloy more homogeneous
and refined near γ microstructure can be obtained in boron modified alloy.
Changes in Lattice Constants and Orientation of <100> and <111> Grains in Nanocrystalline Ni and Ni-Fe Electrodeposits after Annealing
Authors: Lee Dong Nyung
Published: March 2009

Park et al. measured the deposition and annealing textures of nanocrystalline Ni and Ni- 20 % Fe electrodeposits. They found that the deposition texture of major <100> + minor <111> changed to the texture characterized by major <111> + minor <100> after annealing. They also found that the lattice constants of the <100> oriented grains in the as-deposited state were larger than those of <111> oriented grains. In this paper, a model has been advanced to explain the unusual results of lattice constants, and the texture transition has been discussed.
High Temperature Deformation Behavior of Beta-Gamma TiAl Alloy
Authors: Kim J.S. , Lee You Hwan , Kim Young Won , Lee Chong Soo
Published: March 2009

In this study, high-temperature deformation behavior of newly developed beta-gamma TiAl alloys
was investigated in the context of the dynamic-materials model (DMM). Processing maps
representing the efficiency of power consumption for microstructure evolution were constructed
utilizing the results of compression test at temperatures ranging from 1000oC to 1200oC and strain
rates ranging from 10-4/s to 102/s and Artificial Neural Network simulation method. With the help
of processing map and microstructural analysis, the optimum processing condition for the betagamma
TiAl alloy was investigated. The role of β phase was also discussed in this study.
Enhancement of Press Formability of Rolled Mg Alloy Sheet by Using Cross Rolling Processes
Authors: Chino Yasumasa , Sassa Kensuke , Kamiya Akira , Mabuchi Mamoru
Published: March 2009

In this study, two different cross rolling processes, which are effective rolling processes for
a reduction of (0002) plane texture, are introduced. In the first cross rolling process, a sheet specimen
is rotated around the rolling plane normal after each pass. In the second cross rolling process, the roll
axis is tilted against the transverse direction (TD) in the rolling direction (RD) - TD plane. The two
cross-rolling processed were carried out on a AZ31 alloy, and the press formability of cross-rolled
sheets was compared with that of unidirectionally rolled sheets determined by Erichsen tests at 433 –
493 K. Both the cross-rolled specimens exhibited a high press formability, compared to an
unidirectionally rolled alloy. The high press formability of the specimen by the first cross rolling was
due to a reduction in (0002) texture intensity. The high press formability of the specimen by the
second cross rolling was due to not only a reduction in (0002) texture intensity but also grain
refinement.
Properties of AZ31 and AZ91 Sheets Made by Twin Roll Casting
Authors: Numano Masatada , Mori Nobuyuki , Nakai Yoshihiro , Kawabe Nozomu
Published: March 2009

A feasibility study has been made to produce the Mg alloy sheet of high tensile strength and
formability by strip casting and an optimized rolling process. 4mm thickness AZ31 and AZ91 strips
were cast successfully. While the microstructure of the cast AZ31 strip consisted of columnar zones,
the cast AZ91 strip consisted of fine, equiaxed dendrite and fine precipitations.
All samples were rolled to 0.5 mm thickness using an optimized finish-rolling schedule, and their
grain size was around 4μm. The ultimate tensile strength (UTS), yield strength (YS) (0.2% offset) and
elongation (EL) of the rolled AZ31 sheet were higher than those of commercial AZ31B sheet, and the
UTS and YS of the rolled AZ91 sheet were 30% higher than commercial AZ31B sheet. The press
formability of the rolled AZ31 and AZ91 sheet was equal or superior to commercial AZ31B sheet.
Mechanism of Crack Nucleation Analysed by In Situ Observation on Mg-Al-Zn Alloy
Authors: Quan Gao Feng , Cai Li Ming
Published: March 2009

An In Situ observation was made on rolled sheet Mg-Al-Zn alloy (AZ31) in SEM. A type
of mini-tensile specimens was used in three typical material orientations, RD (Rolling direction), 45
(45 degrees to rolling direction) and TD (transverse direction, 90 degrees to rolling direction). It is
found that the plastic deformation occurred unevenly and limited in single grains, shown by micro
extruding steps at grain boundaries. Further deformation concentrated at twinning bands and grain
boundaries, more and finer twinning bands appeared as secondary twins on the original ones. In
different orientations the dislocation slipping mechanism within twinning bands seems to play a
role in different degrees. In RD specimens the slipping mechanism seems predominant, whereas in
TD specimens the twinned steps were obvious. Micro cracks nucleated at internal interfaces: grain
boundaries, interfaces of twinning bands, and intersections of twinning bands as well.
Influence of Misch Metal Addition and Deformation Processes on Microstructure and Mechanical Properties in AZ61 Alloy
Authors: Kang Suk Bong , Kim Hyoung Wook , Jeong Sang Su , Kim Jae Woon
Published: March 2009

Magnesium alloys have been known as the best lightweight metallic materials for various
applications of electronic equipments and automobile parts due to high specific strength and stiffness.
The needs for wrought magnesium alloys have been increased for the application to structural parts in
the form of sheets and bars. However, magnesium has a hexagonal closed-packed (HCP) crystal
structure with a limited number of operative slip systems at room temperature, and its formability is
restricted to mild deformation. The improvement of the formability of magnesium sheets for real
applications is important. In order to increase formability of magnesium sheets at elevated
temperature, one promising way is a grain refinement.
Multifunctional Ti-Si-B-C-N Tribological Nanocomposite Coatings for Aerospace Applications
Authors: Park In Wook , Mishra Brajendra , Kim Kwang Ho , Moore John J.
Published: March 2009

Ti–B–C–N and Ti–Si–B–C–N nanocomposite coatings were deposited on AISI 304
stainless steel substrates by DC unbalanced magnetron sputtering from two (80mol% TiB2–20mol%
TiC and 40mol% TiB2–60mol% TiC) composite targets in various Si target powers. The relationship
among microstructures, mechanical properties, and tribologiacal properties was investigated. The
synthesized Ti–B–C–N and Ti–Si–B–C–N coatings were characterized using x–ray diffraction
(XRD) and x–ray photoelectron spectroscopy (XPS). These analyses revealed that the Ti–Si–B–C–N
coatings are nanocomposites consisting of solid-solution (Ti,C,N)B2 and Ti(C,N) crystallites
distributed in an amorphous TiSi2, SiC, and SiB4 matrix including some carbon, BN, CNx, TiO2, and
B2O3 components. The addition of Si to the Ti–B–C–N coating led to percolation of amorphous TiSi2,
SiC, and SiB4 phases. The Ti–Si–B–C–N coatings exhibited high hardness and H/E values, indicating
high fracture toughness, of approximately 35 GPa and 0.098, respectively. Furthermore, the
Ti–Si–B–C–N coatings exhibited very low wear rates ranging from ~3×10-7 to ~16×10-7 mm3/(N·m).
The minimum friction coefficient of the Ti–Si–B–C–N coatings was approximately 0.15 at low Si
target power between 25W and 50W. A systematic investigation on the microstructures, mechanical
properties, and tribological properties of Ti–Si–B–C–N coatings prepared from two TiB2–TiC
composite targets and one Si target is reported in this paper.
Linking Meso- and Macroscale Simulations: Crystal Plasticity of hcp Metals and Plastic Potentials
Authors: Steglich Dirk , Graff Stéphane , Brocks Wolfgang
Published: March 2009

A crystal plasticity model has been used to simulate channel die experiments on both, pure
magnesium single crystals and polycrystalline textured rolled plates. Deformation mechanisms and
slip system activity can be identified by FE-analyses of single crystals. The role of twinning can be
understood and modeled phenomenologically by an additional slip system. Simulations of polycrystalline
aggregates are used to obtain a representation of the material's phenomenological yield function
in order to describe the plastic deformation behavior using the framework of continuum mechanics.
This allows for accounting for the specific texture and thus for its optimization. The tension-
compression asymmetry, which is typical for mechanically processed magnesium material, can
be reproduced by means of the crystal plasticity and a phenomenological model.
Microstructure and Mechanical Properties of Mg Alloy Sheets Produced by Twin Roll Caster
Authors: Matsuzaki Kunio , Hatsukano Kanichi , Torisaka Y. , Hanada Kotaro , Shimizu Toru , Kato M.
Published: March 2009

Mg-Al-Zn alloys containing 0.5% Ca were strip cast into sheets with a thickness of about
1.0mm by twin roll caster. It is found that the addition of Ca to Mg95Al5-XZnX (wt%)alloys prevents
the oxidation and burning of molten, and makes the melting and casting easy. The as-cast
Mg96Al4Zn0.5Ca0.5 alloy sheet has few cracks at the edge. With increasing Zn content, the generation of
cracks occurs more markedly. The as-cast alloys have equiaxed grains with an average grain size of 10
μm. A fine microstructure is obtained. All the samples consist of single hcp-Mg phase. The yield and
ultimate tensile strength of the as-cast sheets are in the range of 180 to 200 MPa and 265 to 275
MPa, respectively. The alloy Mg95Al2Zn2.5Ca0.5 shows an elongation of 21% as well as a high strength of
275 MPa. The annealing at 400 °C causes an improvement of elongation to 24% and 30% for
Mg96Al4Zn0.5Ca0.5 and Mg95Al2Zn2.5Ca0.5,respectively. A further enhancement of mechanical
properties is expected by an appropriate thermomechanical treatment. The as-cast Mg96Al4Zn0.5Ca0.5
sheet was deep drawn at 250°C and a drawing ratio of 2.0 without cracking . In summery, the Ca
added Mg alloys are suitable for the production of Mg alloy sheets by strip casting and the cast alloy
sheet have high strength with ductility and good formability
Influence of Microstructural Change on Damping Capacity of Mg-X%Li Alloys
Authors: Jun Joong Hwan , Seong Ki Duk , Kim Jeong Min , Kim Ki Tae , Jung Woon Jae
Published: March 2009

The Effects of Li content and annealing treatment on microstructure and damping capacity
for Mg-X%Li alloys have been investigated, based on experimental results from X-ray diffractometry
(XRD), optical microscopy (OM), hardness tests and vibration damping tests in a flexural mode. The
Mg-X%Li alloys containing Li of 3%, 8% and 13% consist of α (HCP) single phase, (α + β (BCC)) dual
phases and β single phase, respectively. In as-rolled state, the damping capacity for Mg-Li alloys shows
a similar level regardless of Li content. The annealing treatments at 200oC and 400οC give rise to an
enhancement of damping capacity only for the Mg-3%Li and Mg-8%Li alloys containing α phase, and
at the same annealing temperature, the Mg-3%Li alloy with fully α structure exhibits higher damping
capacity. This result indicates that the damping capacity of Mg-Li alloys depends principally on α phase,
and that the annealing treatment is necessary to improve its damping capacity.
Effects of Zn and Sn Additions on the Mechanical Properties of Mg-3%Al Alloy
Authors: Kim Jeong Min , Lee Jae Min , Jun Joong Hwan , Kim Ki Tae , Jung Woon Jae
Published: March 2009

A small amount of Zn or Sn was added to Mg-3%Al alloy to improve the formability of
alloy. The elongation of as-rolled alloy was increased at both room temperature and 300oC by
addition of Sn or Zn, even though the tensile strength at room temperature was remarkably
increased only by Zn. When the as-rolled alloy was annealed to be fully recrystallized, the ductility
at room temperature was significantly enhanced, however the elongation at 300oC was rather
decreased probably attributed to the dynamic recrystallization occurred during the tensile test.
Microstructural Characteristics and Creep Properties of Mg-5Al-2Si Alloys Modified with Sn and Sr
Authors: Song Dae Hyun , Lee C.W. , Nam K.Y. , Lee S.W. , Park Y.H. , Cho Kyung Mok , Park Ik Min
Published: March 2009

The effects of tin (Sn) and strontium (Sr) additions on the microstructure and creep
properties of Mg-5Al-2Si (AS52) alloys were investigated. Results showed that the addition of Sn did
not affect the morphology of secondary phase Mg2Si particles but induced the fine and uniform
precipitation of thermally stable Mg2Sn at the grain boundary in the AS52 alloys. However, the
morphology modification of the secondary phase Mg2Si particles from Chinese script shape to refined
polygonal shape was greatly affected by the addition of Sr. Tensile strength and creep resistance were
improved and tensile elongation was also increased in the modified alloy with addition of both Sr and
Sn. Sn is the effective element for precipitating thermally stable Mg2Sn finely and uniformly at the
grain boundary and Sr is the effective element for refining microstructure. Therefore both Sn and Sr
are effective for modifying the microstructure and improving the creep properties of AS52 alloys.
Effect of Aluminum on the Microstructural Characteristics and High Temperature Properties of Mg-xAl-Zn Alloys
Authors: Song Dae Hyun , Lee S.W. , Park Young Do , Park Y.H. , Cho Kyung Mok , Park Ik Min
Published: March 2009

The effect of Al content on the microstructural characteristics, tensile and creep properties
of Mg-xAl-Zn alloy was investigated. The molten Mg-(3~11)Al-Zn alloys of 700°C were poured into
the permanent mould designed to prepare the specimens used in this study. Tensile and creep tests
were carried out for each Mg-Al based alloys. Results show that creep resistance decreased while
tensile strength improved with increasing Al contents. Microstructural study revealed that
morphology and distribution of non equilibrium Mg17Al12 phase is main factor determining the tensile
and creep properties of as cast Mg-xAl-Zn alloys. The final purpose of this study is to construct the
database of already used Mg-Al based alloy and to develop the heat resistant magnesium alloys to
apply transportation systems such as automobile.
Fabrication of Lotus-Type Porous Metals by Continuous Zone Melting and Continuous Casting Techniques
Authors: Nakajima Hideo , Hyun Soong Keun , Park J.S. , Tane Masakazu
Published: March 2009

Lotus-type porous metals with low thermal conductivity are fabricated by continuous
zone melting technique, which possess directional elongated pores. The porous metals have been
able to be fabricated through the conventional casting method by utilizing the solubility gap
between solid and liquid in pressurized gas atmosphere. However, there is a shortcoming that the
pores are coarsened in the part farther from the chill plate in the ingot. In order to overcome such a
shortcoming, we developed the continuous zone melting technique and successfully produced the
lotus-type porous metals with even low thermal conductivity such as stainless steel and superalloys.
Furthermore, from the viewpoint of mass production with low cost, we invented novel ”continuous
casting technique”. The molten metals dissolving gas are solidified continuously by passing through
the mold cooled with chiller and thus, lotus-type porous metal plate as long as one meter was
produced for short time. Sufficient uniformity of the porosity and pore size was obtained in such
long porous ingots. This technique is prospective method for commercial mass production.
Cellular Structures under Impact Loading
Authors: Zhao Han , Elnasri I. , Li Hui Jian
Published: March 2009

This paper presents a study of the strength enhancement under impact loading of metallic
cellular materials as well as sandwich panels with cellular core. It begins with a review of likely
causes responsible for the strength enhancement of cellular materials. A testing method using 60mm
diameter Nylon Hopkinson pressure bars is used to investigate the rate sensitivity of various
metallic cellular materials. In order to identify the factor responsible for the strength enhancement of
those materials, an experimental analysis is performed on a model structure which is a square tube
made of rate insensitive materials. Significant enhancement is experimentally observed under
impact loading, whereas the crushing mode is nearly the same under both static and impact loading.
Finally, an inversed perforation test on sandwich panels with an instrumented pressure bar is also
presented. Such a new testing setup provides piercing force time history measurement, generally
inaccessible. Testing results show a notable enhancement of piercing forces, even though the skin
aluminum plates and the foam cores are nearly rate insensitive.
Density-Graded Aluminum Foams by the Corrosion Method
Authors: Matsumoto Yoshihisa , Brothers A.H. , Dunand David
Published: March 2009

Optimum corrosive density-grading of T6- and solution-treated alloys was studied
using NaOH solutions. Rough corroded strut surfaces in aluminum foams were found to transform
to smooth metallic surfaces with an increase in pH from 10 to 13. For instance, during immersion
in pH13 solutions, pits with large curvatures appeared on strut surfaces, and corrosive mass losses
increased. Strut diameters also decreased, and open cell windows became wider, without an
increase in visible damage. Processing parameters such as pH, corrosion rate, and the surface state
of the struts were examined to optimize final structure. An experimental method for grading of
relative density continuously between 10% and 5% is described.
Crystallization Behavior of Al87Ni5La7Zr1 Metallic Glass
Authors: Wanderka N. , Radiguet Bertrand , Sahoo K.L. , Banhart John
Published: March 2009

Nano-crystalline-amorphous Al based alloys with minor additions of rare earth elements
and transition metals are of technical interest, because of their extraordinary high mechanical
strength. This strengthening effect depends strongly on the alloy composition and the pathway of
crystallisation. The crystallisation behaviour of Al87Ni6La7 and of Al87Ni5La7Zr metallic glass was
studied with complementary methods such as XRD, TEM and 3D-AP. The amorphous matrix of the
Zr-containing glass shows fluctuations of all minor elements on the nanometer scale. It is suggested,
that these fluctuations act as nucleation zones for the crystallization of the glass during annealing.
Thermal and Mechanical Properties of Mg-Cu(Ni)-Y(Gd) Amorphous Alloys
Authors: Hung T.H. , Chang Y.C. , Chen H.M. , Tsai Y.L. , Huang J.C. , Jang Jason S.C. , Nieh T.G.
Published: March 2009

The thermal and mechanical characteristics of various Mg-Cu(Ni)-Y(Gd) metallic glassy
alloys prepared by melt spinning are examined using differential scanning calorimetry (DSC),
thermomechanical analyzer (TMA), and instrumental nanoindenter. The replacement of Y by Gd
appears to benefit both the thermal and mechanical properties, while the replacement of Cu by Ni
improves only the hardness and modulus, with the sacrifice of thermal characteristics. The
amorphous Mg-Cu-Gd based alloys can be fabricated into rods with a diameter greater than 6 mm,
with minimum porosity and reasonable toughness.
Recent Research and Development in Metallic Materials for Biomedical, Dental and Healthcare Products Applications
Authors: Niinomi Mitsuo
Published: March 2009

Non-toxic allergy free alloying elements are mostly selected for preparing metallic
biomaterials. Currently, functionalities such as low modulus, shape memory, super elasticity, etc. are
required for the metallic biomaterials, especially for β type titanium alloys. The harmonization of
metallic, ceramic, and polymer biomaterials is needed for advanced biomaterials in the future.
Titanium and its alloys are attracting considerable attention with regard to applications not only in the
biomedical field, but also for dental and healthcare products. In dentistry, titanium and its alloys are
applied to dental products such as crowns, inlays, bridges, etc., as well as dental implants. For
fabricating dental products, the dental precision casting process is important. A new dental precision
casting process using calcia is currently being developed. Noble alloys such as gold base or silver
base alloys are widely applied for the precision casting of dental products. Allergy-free elements,
particularly Pd-free low- noble dental alloys are required.
Metastable Transition-Metal System Bulk Alloys Prepared by MA and Shock Compression
Authors: Mashimo Tsutomu , Fan Xu , Huang Xin Sheng
Published: March 2009

Mechanical alloying (MA), super cooling process, etc. have been used to prepare
amorphous phases, metastable solid solutions, nanocrystals, and so on. It is important to consolidate
these powders for evaluating the physical properties, and for applications. On the other hand, shock
compression can be used as an effective consolidation method for metastable material powders
without recrystallization or decomposition. We had prepared metastable transition-metal system
bulk alloys and compounds (Fe-Co, Fe-Cu, Fe-W, Co-Cu, Sm-Fe-N systems, etc) by using MA and
shock compression. The Fe-Cu and Co-Cu metastable solid solutions showed a fit curve to the
Slater-Pauling one. The Co-Cu metastable solid solution bulk alloy showed a magneto-resistance.
The Fe-Co fine-grained bulk alloys show the higher coeicivity than that of molten alloy. In this
paper, the preparation and magnetic properties of the metastable alloys (Fe-Co, Fe-Cu, Co-Cu
systems) are reviewed, and the applications to materials science and engineering are discussed.
EXAFS Study on Atomic Distribution Change during Tensile Deformation of Metallic Glass
Authors: Nasu Toshio , Usuki Takeshi , Onodera Y. , Sakurai Masaki , He B. , Zhong W. , Wei Z. , Wei S. , Zhang Wei , Inoue A.
Published: March 2009

The purpose of this research is to investigate the micro-mechanism of anelastic behavior of
metallic glass. The changes of atomic arrangement in Cu50Zr50 metallic glass were observed directly
by EXAFS method during tensile deformation. The transmission-mode EXAFS measurements
around Zr K-edge and Cu K-edge of the sample in various amounts of tensile deformation conditions
were done. The interatomic distance between Cu-Zr increased, and that between Zr-Zr decreased
simultaneously, with the amount of tensile deformation increase of the sample at first stage of
deformation. When the atomic distances reached to certain values respectively, they recovered to the
initial values of no tensile deformation condition at first stage, and then the atomic distances changed
as same manner as the first stage of deformation, respectively. This is the first observation on the
change of atomic arrangement during tensile deformation of metallic glass.
Effects of Additional Elements on Microstructures of Zr-Based Metallic Glass Ribbons
Authors: Yamamoto Tokujiro , Yodoshi Noriharu , Kimura Hisamichi , Inoue Akihisa
Published: March 2009

Effects of Fe, Co and Al addition to Zr55Al10Ni5Cu30 and Zr70Cu30 metallic glass ribbons
were studied. 20 at.% of Fe addition prevented Zr55Al10Ni5Cu30 molten alloys from being
supercooled and resulted in nanocrystallization, while Zr55Al10Ni5Cu30 alloys containing 20 at.% Co
could be quenched into a supercooled liquid region. Fe addition also degraded Zr70Cu30 metallic
glass, while Al addition improved both glass phase stability and mechanical properties.
Degradation of Zr-based metallic glass by Fe addition originates in the large negative enthalpy of
mixing Fe with Cu.
Structure of Glass and Liquid Studied with a Conical Nozzle Levitation and Diffraction Technique
Authors: Mizuno Akitoshi , Kohara Shinji , Matsumura Seiichi , Watanabe Masahito , Weber J.K.R. , Takata Masaki
Published: March 2009

Two topics are described for structure analyses of glass and liquid using a combination of
conical nozzle levitation (CNL) technique and diffraction experiments. The structure of high-purity
bulk forsterite (Mg2SiO4) glass synthesized by a CNL technique has been determined by a
combination of high-energy x-ray, neutron diffraction, and reverse Monte Carlo (RMC) modeling
technique. The 3-dimensional atomic configuration derived from RMC modeling revealed that
unusual network structure. In order to study structures of high-temperature and undercooled liquids, a
CNL system has been developed and integrated with the two-axis diffractometer for glass, liquid, and
amorphous materials at SPring-8, which is one of the third-generation synchrotron source.
High-energy x-ray diffraction experiments were performed to obtain reliable diffraction data for the
liquid phase of metallic glass-forming Zr-Cu binary alloys.
Glass Formation Range of Mg-Based Bulk Metallic Alloys
Authors: Soubeyroux Jean Louis , Gorsse Stéphane , Orveillon G.
Published: March 2009

New bulk metallic glasses (BMG) have been synthesized in the Mg-Cu-RE systems
(RE= Y, Gd) with high critical diameter. In order to determine the glass forming range of these
ternary systems, the calculation of the onset of driving forces (ODF) has been performed and has
shown a large composition range for BMG formation. The synthesis of particular compositions in
this domain has shown that all the produced alloys present a high glass forming ability (GFA)
measured by DSC experiments. The ODF model, synthesized alloys by mould casting,
characterization by X-ray diffraction and DSC techniques are presented.
Growth and Atomistic Structure Study of Disordered SiGe Mixed Semiconductors
Authors: Yonenaga Ichiro , Sakurai Masaki , Sluiter Marcel H.F.
Published: March 2009

The atomistic structure of Czochralski-grown SixGe1-x binary mixed semiconductor was
studied experimentally and theoretically. By extended X-ray absorption fine structure (XAFS)
studies it was found that bulk SiGe semiconductor is a random mixture and that the Ge-Ge, Ge-Si
and Si-Si bond lengths maintain distinctly different lengths and vary in a linear fashion against the
alloy composition across the whole composition range 0 < x < 1, in good agreement with
expectations derived from the ab-inito electronic structure calculations. The result indicates that
SiGe is a suitable model for a disorder mixed material and that the bond lengths and bond angles are
distorted with the composition.
Understanding Process and Property Relationships in Aluminum Alloy Friction Stir Welds
Authors: Reynolds Anthony P.
Published: March 2009

Friction stir welding (FSW) has been in use for nearly fifteen years and a significant
body of published research regarding process/property/structure relationships is now available;
particularly with respect to FSW of aluminum alloys. In this paper, some pertinent literature will be
reviewed and an attempt made to tie the numerous experimental observations together through some
unifying concepts. Examination of relationships among control and response FSW process
variables (respectively e.g. tool rotation rate and torque) and weld microstructure and properties can
provide important insight regarding how weld properties develop and how best to approach process
development for different alloy classes.
Structure Instability of Metallic Glass Zr50Cu40Al10 in Low Temperature
Authors: Fukami Takeshi , Nanbu A. , Fukatani M. , Okai Daisuke , Akeno Y. , Yokoyama Yoshihiko , Yamasaki Tohru , Inoue Akihisa
Published: March 2009

In order to examine mechanical properties of a metallic glass Zr50Cu40Al10 in low
temperature below room temperature, the temperature T dependence of mechanical resonance of
ultrasonic wave are measured. The mechanical resonance frequency in an as-quenched sample
shows an abrupt increase at 200K for longitudinal wave and 160 K for transverse wave with
decreasing T. After this abrupt increase, the sound propagation cannot be detected below these
temperatures but the wave propagation is restored with increasing T and there is an abrupt decrease
at 260K for the both wave modes. The similar hysteresis is observed in temperature dependence
of the electrical resistivity. These suggest a kind of structure instability of Zr50Cu40Al10 in low
temperature region.
The c/a Ratio in Quenched Fe-C and Fe-N Steels - A Heuristic Story
Authors: Sherby Oleg D. , Wadsworth Jeffrey , Lesuer D.R. , Syn C.K.
Published: March 2009

The body-centered tetragonal (BCT) structure in quenched Fe-C steels is usually
illustrated to show a linear change in the c and a axes with an increase in carbon content from 0
to 1.4%C. The work of Campbell and Fink, however, shows that this continuous linear
relationship is not correct. Rather, it was shown that the body-centered-cubic (BCC) structure is
the stable structure from 0 to 0.6 wt%C with the c/a ratio equal to unity. An abrupt change in
the c/a ratio to 1.02 occurs at 0.6 wt%C. The BCT structure forms, and the c/a ratio increases
with further increase in carbon content. An identical observation is noted in quenched Fe-N
steels. This discontinuity is explained by a change in the transformation process. It is proposed
that a two-step transformation process occurs in the low carbon region, with the FCC first
transforming to HCP and then from HCP to BCC. In the high carbon region, the FCC structure
transforms to the BCT structure. The results are explained with the Engel-Brewer theory of
valence and crystal structure of the elements. An understanding of the strength of quenched
iron-carbon steels plays a key role in the proposed explanation of the c/a anomaly based on
interstitial solutes and precipitates.
Strain Scanning in Australia: Instrumentation and Recent Experiments
Authors: Kirstein Oliver , Ripley Maurice I. , Tawfik David
Published: March 2009

Neutron scattering using diffraction techniques is now recognised as the most precise
and reliable method of mapping sub-surface residual stresses in materials and industrial devices. It
was therefore decided to build the dedicated strain scanner KOWARI among the first suite of
instruments for the new Australian Replacement Research Reactor OPAL. In order to support the
new instrument and familiarize the Australian user community with the technique a „Neutrons for
Engineering“ project has been established to provide a fully integrated residual stress service. To
make use of the neutrons at Australias HIFAR reactor the existing three-axis spectrometer has been
refurbished and modified to allow strain measurements. The Australian Strain Scanner (TASS) will
operate until the new strain scanner becomes operational in 2006. Apart from giving an overview
about the technique and properties of the new strain scanner we would like to present and discuss
two case studies: a) residual-stresses obtained from a break-disc of a car and b) residual-stresses
within a flash-butt welded plate cut out of a railway.
Temperature Distribution, Phase Transformations and Residual Stresses in Heat Treatment of Grinding Balls
Authors: Camurri Carlos , Carrasco C. , Dille Jean
Published: March 2009

The goal of this work is to model the temperature distribution, phase transformation and
residual stresses induced during the heat treatment of 3 and 5 inches diameter grinding balls. In the
first step, the radial distribution of temperature inside the balls was calculated and validated
experimentally. During the quenching, the model considers factors such as the heating of the water
and the formation of a steam layer that surrounds the balls in the beginning of the treatment. In a
second step, with the temperature distribution, the CCT curves of the steel and the Koistinen-
Marburger equation, the radial distribution of martensite was determined during the heat treatment.
Finally, in the third step, the residual stresses field was modeled considering the temperature
distribution, the force equilibrium equations and the constitutive thermo-elastic relationships, where
the expansion due to the austenite – martensite transformation was included.
In the temperature distribution, a good experimental-theoretical agreement was obtained, with
differences at the end of the quenching no higher than 0,5 %. Respect to the residual stresses, the
model indicates that the maximum tensile values occur at certain depth below the surface of the
balls and the experimental evidence of the behavior of the balls in a mill simulator, as well as the
measured residual stresses by means of DRX shows an acceptable agreement with the theoretical
predictions.
The Developments of Plasticity Processing: 3M Strategy
Authors: Zhou Xian Bin , Lang Li Hui
Published: March 2009

As one of the oldest manufacturing methods, the plasticity processing still is the
basic and important way to produce the components in this period of IT. In the recent years,
the plasticity processing has gained more attentions and a further development. At the same
time, for the purpose of the sustainable development and the big profit, the environmental
friendly methods should be applied into the plasticity processing. Based on the introduction to
the development of the precise forging and stamping, this paper described the development
trends and the basic needs of the plasticity processing and indicated that it is demanded to
speed up the change of plasticity processing from the experimental or trial-and-error types to
the scientific analysis and to realize more of precision, more of economy and more of
greening (3M strategy) for the processing.
Estimation of Contact Interface between Tool and Workpiece in Cold Forming Using FEM Analysis
Authors: Saiki Hiroyuki , Marumo Yasuo , Ruan Li Qun , Kozasa Junpei
Published: March 2009

The effect of the flow stress of solid lubricant for cold forging on the tribological
conditions was investigated using a rigid-plastic finite element method. The thickness of lubricant
film decreases with decreasing flow stress of the solid lubricant and then decreases rapidly. The
apparent friction coefficient also decreases with the decrease in the flow stress of the solid lubricant.
The thickness of lubricant film tends to decrease with decreasing friction shear factor. When flow
stress of solid lubricant is low, the thickness of lubricant film decreases remarkably with increasing
tool stroke. We can observe a good correlation between the flow stress of solid lubricant, friction
shear factor, minimum film thickness and apparent friction coefficient.
A New Challenge of Polymer Thermoelectric Materials as Ecomaterials
Authors: Shinohara Yoshikazu , Imai Yoshio , Isoda Yukihiro , Hiraishi Kentaro , Nakanishi Hachiro
Published: March 2009

Typical conductive polymers of poly(3-alkylthiophenes) were synthesized by oxidative
polymerization. Polythiophene with no side chain was also electrolyticaly polymerized. Alkyl side
chains were CnH2n+1 with n=4, 6, 8, 12. The regioregularity with the HT linkage was larger than 99%
based on NMR analysis. We have evaluated the effect of side chain size on the thermoelectric
properties of Seebeck coefficient and electrical conductivity. The results were as follows: 1) Seebeck
coefficient decreased with an increasing electrical conductivity. 2) High Seebeck coefficient >1mV/K
was observed at low electrical conductivity <10-2S/cm. 3) Small side chains, especially no side chain
caused higher thermoelectric properties of polythiophene series.
Life-Cycle Evaluation of Ecobalance Performance of Ecomaterial-Type Building Materials by Multiple Eco-Indicator Method
Authors: Fukushima Toshio
Published: March 2009

Ecomaterial-type building materials are classified based upon 6 row×8 column
eco-life-cycle matrix table combining 8 life-cycle stages of resources gathering, transportation,
production, assembly/construction, in-service/maintenance and modernization, demolition,
recycle/reuse/reproduction, and reduce/final waste with six eco-balance evaluation items of long
service life, resources circulation, reduction of harmful substances, resources and environmental
capacities, materials efficiency ,and health safety. Evaluation indicators other than life cycle
inventory (LCI) are shown as methods of ecobalance performance. In each life stage, each
ecomaterial is evaluated as radar chart by 5 step indices by six eco-balance evaluation item (multi
eco-indicators）.
Three-Dimensional Simulation of Coarsening and Grain Growth in Sintering
Authors: Wakai Fumihiro
Published: March 2009

The interparticle mass transport causes the larger particles to grow at the expense of the
smaller particles in the process of sintering. Coarsening during sintering results from surface motion,
while grain growth results from grain boundary motion. The three-dimensional simulation was
performed to study coarsening and grain growth during sintering by using the Surface Evolver
program. The coarsening and grain growth were affected by the ratio of grain boundary energy to
surface energy, the ratio of grain boundary mobility to surface mobility, the size of a particle, and its
coordination number.
Determination of Percolation Threshold for Random Boundary Network on the Basis of EBSD/OIM Observations
Authors: Tsurekawa Sadahiro , Nakamichi Shinya , Watanabe Tadao
Published: March 2009

Grain boundary engineering through the control of grain boundary character distribution
(GBCD) has been extensively employed as a powerful tool for achieving enhanced properties and for
development of high performance both structural and functional polycrystalline materials. Many
efforts were made firstly to increase the frequency of low-energy CSL boundaries of polycrystalline
materials in grain boundary engineering. However, the connectivity of grain boundaries can be an
important microstructural parameter governing bulk properties of polycrystalline materials as well as
the GBCD. In the present work, the connectivity of random grain boundaries was quantitatively
evaluated using both the triple junction distribution and random boundary cluster length on the basis
of SEM-EBSD/OIM observations, and then these evaluated parameters were linked to intergranular
corrosion of SUS304 stainless steel. We have found that the length of the maximum random
boundary cluster drastically decrease with increasing CSL boundaries in the fraction ranging 60 –
80% CSL boundaries, which leads to percolation threshold occurring at approximately 70±5% CSL
boundary fraction (at 30±5% random boundary fraction). The experimentally observed percolation
threshold is much higher than theoretically obtained one based on randomly assembled network (at
35% resistant bonds for a 2D hexagonal lattice). In addition, the fraction of resistant triple junctions is
found to increase with increasing the the CSL boundary fraction. An increase in the frequency of
resistant triple junctions can enhance intergranular corrosion resistance of polycrystalline austenitic
stainless steel even if the GBCD is the same.
Phase Transformation Modeling of Medium-Carbon Forging Steel
Authors: Tanaka K. , Hara M. , Yogo Yasu , Nakanishi Kou , Capdevila Carlos
Published: March 2009

The kinetics of phase transformations in medium-carbon forging steels (MCFS) have been
modeled based on CALPHAD multicomponent thermodynamics and the classical nucleation-growth
theory. New treatments include the time dependency of parabolic growth rate of proeutectoid ferrite
(α) , which account for the soft impingement effect by carbon enrichment in austenite (γ). And a
potential transition of γ/α interface equilibrium has also been considered depending on temperatures
and velocity of the moving interface. To make a realistic prediction of the onset of pearlite (P)
transformation, a normal distribution of γ grain size has been assumed and successive α→P
transformation kinetics in each grain size have been summated.
The developed program coupled with thermodynamic solver, 'ThermoCalc', calculated the isothermal
kinetics of MCFS and has been found to predict well the effect of minor difference of chemical
composition / holding temperatures.
Characterization of the Heat Transfer Boundary Conditions during Cooling of a Horizontal Disk with a Water Column
Authors: Hernández-Morales Bernie , Téllez-Martínez J.S. , Sánchez-Sarmiento G.
Published: March 2009

To model the microstuctural and mechanical responses of quenched metallic components,
the evolution of the thermal field must be known precisely; the latter, in turn, depends on
accurate values of the thermal boundary conditions. In this work, the heat transfer boundary conditions
on both sides of a stainless steel disk, held horizontally while a water column impinged on its
lower surface to cool it from 850°C to room temperature, were characterized as heat flux histories
which are functions of the radial coordinate. Thermal responses, measured with embedded thermocouples
and a computer-controlled data acquisition system, were used to estimate the heat flux histories
by solving the corresponding inverse heat conduction problem (IHCP), considering radial
symmetry. The optimization problem also included the estimation of sub-areas associated with different
heat extraction rates on both the lower and upper surfaces of the disk. The fluctuating interaction
between the water column and the cooling disk was captured in the estimated heat flux histories.
The estimated thermal boundary conditions were validated by computing the thermal response at
the thermocouple locations by solving the direct heat conduction problem (DHCP) with a computer
program based on the finite-element method. A good agreement between experimentally determined
and computed thermal responses was observed, thus verifying the methodology employed.
The Influence of Injection-Molding Parameters on the Dimensional Accuracy
Authors: Kampuš Zlatko , Berginc Boštjan , Šuštaršič Borivoj
Published: March 2009

The most influential injection-molding factors were chosen and the Taguchi method of experiment
planning was used to determine the number of the experiments needed. The test specimens in the
form of a standardized tensile specimen were injection-molded under six different conditions. The
analysis of variance was used to determine the parameters influencing the dimensions of a green
part. Under the same conditions the test specimens were then subjected to debinding and sintering,
and the influences of injection on the mass, mechanical properties and dimensions were analyzed
once again.
Models and Equations for Atomic Transport Coefficients of Liquid Metals: Viscosity and Self-Diffusivity
Authors: Iida Takamichi , Tripathi Nagendra , Isac M. , Guthrie Rod I.L.
Published: March 2009

The current article presented appropriate models using a new parameter recently
introduced by the authors to accurately predict the atomic transport coefficients, i.e. viscosity and
self-diffusivity, of liquid metallic elements at their melting points. The models for both the meltingpoint
viscosity and self-diffusivity are expressed in terms of well-known physical quantities; atomic
mass, atomic volume, melting point, melting-point surface tension, and the new parameter T ξ .
Moreover, the authors derived expressions for the temperature dependence of the atomic transport
coefficients of liquid metallic elements in terms of melting point temperature. These two models
give very good agreement with experimental data for various metallic liquids. Using the models,
self-diffusivities were predicted for liquid aluminum, calcium, and magnesium.
Modeling of Generalized Continua on Macroscopic Scales: Towards Computational Mechanics of Microstretch Continua
Authors: Kirchner Nina , Kirchner E.
Published: March 2009

First numerical results for microstretch continua, embedded in a hierarchy of generalized
continuum models,will be presented. The governing equations are derived using a variational
approach, providing an alternative to Eringens approach of modeling microstretch continua. A
constitutive theory for linear elastic microstretch continua is formulated and used in the simulations.
Simple examples will be investigated in order to demonstrate the compatibility of the model hierarchy.
The results obtained so far are promising and suggest that a further in-depth analysis of (in)elastic
microstretch continua based on the here proposed consistent and computationally simple approach to
microstructured materials is worthwile.
A Multiscale Approach for Composite Materials as Multifield Continua
Authors: Trovalusci Patrizia , Sansalone Vittorio , Cleri Fabrizio
Published: March 2009

A continuum model for composite materials made of short, stiff and tough fibres
embedded in a more deformable matrix with distributed microflaws is proposed. Based on the
kinematics of a lattice system made of fibres, perceived as rigid inclusions, and of microflaws,
represented by slit microcracks, the stress-strain relations of an equivalent multifield continuum is
obtained. These relations account for the shape and the orientation of the internal phases and
include internal scale parameters, which allow taking into account size effects. Some numerical
analyses effected on a sample fibre-reinforced composite pointed out the influence of the size and
orientation of the fibres on the gross behaviour of the material.
Macro and Macro/Micro Models of Solidification - Numerical Aspects of Process Simulation
Authors: Szopa Romuald
Published: March 2009

The solidification models basing on the Fourier equation with the additional term
controlling the kinetics of phase transition are discussed. The different approaches to this term
definition lead to the different solidification models, in particular the macro and the macro/micro ones
can be taken into account. In the case of macro description the equation in which the parameter called a
substitute thermal capacity is considered, while in the case of macro/micro approach the linear or
exponential models of crystallization can be introduced. The solution of the problem can be found
using the numerical methods. In this paper the boundary element method using discretization in time is
applied, the examples of numerical simulations are also shown.
Kinetics of the Austenite-to-Ferrite Phase Transformation - From the Intrinsic to an Effective Interface Mobility
Authors: Gamsjäger Ernst
Published: March 2009

Recent studies indicate that the austenite(γ)-to-ferrite(α) transformation kinetics in low
alloyed steels is solely controlled by the intrinsic mobility of the interface at least in the initial stages
of ferrite growth. Then, diffusion processes in the interface significantly retard ferrite growth, so that
bulk diffusion of the fast diffusing interstitial component carbon becomes relevant. Two series of
dilatometer tests, one from a low to ultra-low carbon steel [1] (alloy A) and the other from an Fe-Mn
steel [2] (alloy B), are considered. In case of alloy A the first stage of the transformation kinetics is
apparently controlled by the intrinsic interface mobility, whereas in the second stage carbon diffusion
in the interface and in the bulk material comes into play. The transition region can be modeled by an
effective mobility, which depends on the interface velocity. In the second stage the interface mobility
depends on the temperature only. In case of alloy B a hierarchical model allows for a direct estimation
of the intrinsic mobility. The numerical results indicate that the interface mobility also changes from
an intrinsic mobility at the initial stage of the transformation to an effective mobility due to solute
drag during the transformation process.