bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of Fe3AlC Base Alloy by Mechanical Alloying and Vacuum Hot Pressing
Authors: Isonishi Kazuo
Published: March 2009

Fabrication of Fe3AlC matrix in-situ composite, reinforced by a FeAl phase, was
studied by using the powder metallurgical processing route. Especially, in order to disperse the
second phase more finely, we chose the mechanical alloying process. We investigated the
microstructural and mechanical properties of the consolidated material. After consolidation by
vacuum hot pressing, the compact showed almost full density and consisted of a Fe3AlC matrix and
FeAl second phase (average particle size was less than 1μm). The compact showed HV746, which
was higher than that of the arc melted Fe3AlC monolithic material, HV650.
Development of High Strength Sintered Steel by High Pressure Warm Compaction Using Die Wall Lubrication
Authors: Matsumoto Nobuhiko , Miyake Toshitake , Kondoh Mikio , Ando Kimihiko , Tanino Hitoshi
Published: March 2009

The high pressure compaction without internal lubricant and the high green density even
with the pore free density were achieved by the newly developed die wall lubricant for warm
compaction. This developed die wall lubricated warm compaction followed by high temperature
sintering resulted in improved mechanical property and almost no dimensional change. In this
paper, the effects of increasing the green density on the sintered density, the dimensional change
and the mechanical property are mainly discussed.
The Application of P/M Advanced Techniques to Sintered Gears
Authors: Bao Chong Xi , Shen Zhou Qiang , Shu Zheng Ping
Published: March 2009

The processes of P/M affect the properties of sintered gears. The different techniques of P/M lead to the different properties of sintered gears. This paper summarizes new progress in powder metallurgy for sintered gears. These progresses include warm compaction, high velocity compaction, sinter hardening, high temperature sintering, infiltration, CNC powder press and surface densification etc.
Micro Fabrication Process of Powder Compact with Semi-Solid Mold
Authors: Tsumori Fujio
Published: March 2009

New powder compaction process, in which a Bingham semi-solid/fluid mold is utilized,
is developed to fabricate micro parts. In the present process, a powder material is filled as slurry in a
solid wax mold, dried and compressed by either of conventional pressing methods, such as isostatic
pressing or die compaction. It is important to use slurry for filling because dry powder is hard to fill
in the micro cavity. It is also essential to control process temperature to treat micro parts. The wax
mold is heated during compaction and becomes semi-solid state, which can acts as a pressurized
medium for isostatic compaction. Since the compacted micro parts are very fragile, the mold's
temperature is controlled to higher than its melting point during unloading, to avoid breakage of the
compacts. To demonstrate effectiveness of this process, some micro compacts of alumina are shown
as examples.
A Solution for Diffusion Equations and the Distribution of Alloying Elements in Sintered Alloys
Authors: Wang Chong Lin
Published: March 2009

The error function can be calculated based on the Simpson method through a subroutine
program. An integration program by FORTRAN language was made for diffusion equations of
extended source with infinite extent and limited extent. The distribution curves of alloying elements
could be driven from calculated results written in ASCII code. The results on some alloying
elements such as C, Co, Cr, Mn, Mo, Ni and V’s diffusion in iron, showed the diffusion distance for
Ni and Mo can only be 1~3 μm and more distance for Co at common sintering temperature of
1120°C. Increasing the sintering temperature up to 1300°C, distribution curve could be improved.
To refine the particle size of the added elements down to a scale of micrometers is an effective way
to get homogeneous distribution.
Sintering Behaviour of Al-Cu-Mg-Si Blends
Authors: Falticeanu C. Lucien , Chang I.T.H. , Kim J.S. , Cook R.
Published: March 2009

The increasing demand for automotive industries to reduce the weight of the vehicles has
led to a growing usage of Al alloy powder metallurgy (P/M) parts such as camshaft bearing caps,
shock absorber pistons and brake calipers [1,2]. In order to control the sintered microstructure and
mechanical properties of the aluminium alloy powder metallurgical (P/M) parts, it is essential to
establish a fundamental understanding of the microstructural development during the sintering
process. Current research at Birmingham University is focussed on the investigation of the sintering
behaviour of Al-Cu-Mg-Si powder blends using a combination of Scanning Electron Microscopy,
Energy Dispersive Microanaylsis (SEM) and Differential Scanning Calorimetry (DSC). This paper
presents a detailed study of the effect of temperature and initial starting materials on the evolution
of microstructure during the sintering of Al-Cu-Mg-Si blends for PM.
Sintered Duplex Stainless Steels Corrosion Properties
Authors: Dobrzański Leszek Adam , Brytan Z. , Actis Grande Marco , Rosso Mario
Published: March 2009

This work presents mechanical properties and corrosion resistance of duplex stainless
steels obtained through powder metallurgy starting from austenitic X2CrNiMo17-12-2 (AISI 316L),
martensitic X6Cr13 (AISI 410L) powders by controlled addition of alloying elements in the proper
quantity to obtain the chemical composition of the structure similar to biphasic one. In the mixes
preparations the Schaffler’s diagram was taken into consideration. Prepared mixes of powders have
been sintered in a vacuum furnace with argon backfilling. After sintering rapid cooling was applied
using nitrogen. Produced duplex stainless steels have been studied by SEM with EDS and light
optical microscopy (LOM) and X-rays analysis to determine obtained structures. Corrosion
properties have been studied through electrochemical methods in 1M NaCl.
Effect of Powder Size of Mg-Zn-Y Alloy on the Consolidation
Authors: Kim Taek Soo , Chae H.J. , Lee J.K. , Jeong Ha Guk , Kim Young Do , Bae Jung Chan
Published: March 2009

MgZn4.3Y0.7 alloy powders were prepared using an industrial scale gas atomizer,
followed by warm extrusion. The powders were almost spherical in shape. The microstructure of
powders as atomized and bars as extruded was examined as a function of initial powder size
distribution using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscope
(EDS) and X-ray Diffractometer (XRD). The grain sizes were decreased with extruding as well as
decreasing the initial powder sizes. Both the ultimate strength and elongation were enhanced as the
initial powder sizes were decreased.
Investigation of Ageing Phenomena in CuAlNi Based Shape Memory Alloys
Authors: Benke Marton , Mertinger Valéria , Nagy E. , Van Humbeeck Jan
Published: March 2009

The ageing phenomena and its effect on the thermoelastic martensitic
transformation was investigated in three Cu-base SMAs. The transformation temperatures
shifted to higher temperatures due to aging in the beta-phase.
To increase the alloy’s ductility, a definite amount of Mn (4 wt%) and Fe (2 wt%) were added
to the ternary alloy. The thermoelastic martensitic transformation was found in the not-aged
samples of the CuAlNiMn and CuAlNiMnFe alloys. This transformation was destroyed due
to ageing heat treatments by a fairly unknown exothermic process. The thermoelastic
martensitic transformation appeared again in the aged CuAlNiMn and CuAlNiMnFe samples
after keeping them on room temperature for a few months.
This phenomena was investigated by DSC, SEM, TEM, and XRD.
Precipitation Microstructure of Ultrafine-Grained Al-Zn-Mg Alloys Processed by Severe Plastic Deformation
Authors: Gubicza Jenő , Schiller I. , Chinh Nguyen Q. , Illy Judit
Published: March 2009

Supersaturated Al-4.8Zn-1.2Mg-0.14Zr and Al-5.7Zn-1.9Mg-0.35Cu (wt.%) alloys were processed by Equal-Channel Angular Pressing (ECAP) at 200°C. The crystallite size distribution and the characteristic parameters of the dislocation structure of both Al matrix and precipitates were determined by X-ray diffraction line profile analysis, which has been complemented by transmission electron microscopy (TEM) observations. Results of these investigations show that the bulk ultrafine-grained microstructure with high dislocation density produced by ECAP has strong influence on the precipitation process, resulting in high strength in both alloys.
Mechanical Investigation of Hemp Fiber Reinforced Polypropylene with Different Types of MAPP Compatibilizer
Authors: Mezey Zoltán , Czigány Tibor
Published: March 2009

Mechanical properties of hemp fiber reinforced polypropylene were investigated. Hemp
fibers were carded together with polypropylene fibers, and needle punched. Composites were
prepared by hot pressing of the PP/hemp mats. Hemp content was varied between 0 and 50 % by
weight, in 10% steps. A treatment with two different maleic anhydride grafted polypropylenes was
applied in order to increase the fiber/matrix surface adhesion. Tensile, three-point bending and
Charpy tests were carried out on the treated and untreated composites.
Replacement of Imported Drawn Tubes Built in Heat Exchangers by Longitudinal Seam Pipes Produced by DUNAFERR
Authors: Dénes Éva , Fülöp Piroska , Gergely Judit , Menyhárt Ferenc , Tóth Sándor , Buza Gábor , Verő Balázs
Published: March 2009

Diverse technologies in domestic enamelling production for machining, cutting and
joining process are applied. The experiments presented in this paper focused on the opportunities
of replacement of the drawn tubes built in heat exchangers longitudinal seam pipes produced by
DUNAFERR Co. Ltd. The steel grade which satisfies the requirement of two-side enamelling,
formability and after-fire sag resistance has been investigated. It has been shown that the coldrolled
DC 04 EK-B steel grades stand all demands needed and therefore are able to replace the
imported drawn tubes presently used.
Effect of Cladding on the Reactor Pressure Vessel Safety
Authors: Gémes György András
Published: March 2009

It is common for the most reactor pressure vessel (RPV) of light-water reactors used
today, that the RPV made of ferrite-perlitic steel is cladded with an austenitic layer, which well
resists corrosion influence. The cladding is manufactured by welding, the technology (mode of
application, number of layers) is different by each manufacturer. This is the layer which comes into
contact with the working media first, and is of course in cohesive contact with the RPV material.
The aim of this study is to demonstrate the new approach, used for assessing the safety of the
reactors today. This approach plays a decisive role in the lifespan calculation of already operating
nuclear power stations, including the extension of their service period.
Color Etching for Characterization the Grain Orientation in Spheroidal Graphite Cast Iron
Authors: Kardos Ibolya , Gácsi Zoltán , Szabó Péter János
Published: March 2009

Color etching is a widely used technique for visualizing different phases in metallic materials. Its advantage to the traditional etching techniques is that it gives additional information within one phase, namely, the color shade of a given phase can change in a certain range. This paper demonstrates that, due to the physics of the color etching, the shade of a phase also depends on the crystallographic orientation of the investigated grain. As a test material, spheroidal graphite cast iron was used, and individual grain orientation was identified by automated electron back scattering diffraction (EBSD). Results showed that there is a strong correlation between grain orientation and the shades obtained by color etching.
Development of a Novel Vibrating Sample Magnetometer
Authors: Mészáros István
Published: March 2009

A new type of vibrating sample magnetometer (VSM) was designed for measuring the magnetic properties of soft and hard magnetic materials is described. The developed instrument differs from the traditional Foner type because in our system the motion of the specimen is parallel with the lines of the external magnetic field. Therefore, this instrument can be called parallel motion vibrating sample magnetometer (PMVSM). The special vibrating system contains a vibrating rod which holds the specimen. This arrangement can make the sample replacement and positioning fast and convenient. Because of the versatility of the PMVSM instrument it could be a useful measuring device for materials science laboratory and educational purposes as well.
Coronary Stents’ Materials and Examinations of Surface and Expansion Features
Authors: Ring György , Bognár Eszter , Dobránszky János
Published: March 2009

In our study we summarise the materials and manufacturing technologies of coronary stents used nowadays. Different testing methods for stent’s features are presented and main expansion features such as recoil and foreshortening are determined. The most frequent failures caused by the expansion of the coronary stents are also shown.
Metallographic Investigation of TRIP Steels
Authors: Takács-Szabó A. , Verő Balázs , Sólyom Jenő
Published: March 2009

Results of the X-ray diffraction (done by computer quantitative phase analysis) and
metallographic miscroscopy (colour etching and computer image analysis) inspections aimed at
determining the residual austenite content of modern TRIP steel sheets produced at Dunaferr.
Developing Mechanical Properties and Electrical Conductivity of Cu Alloys by Jominy End-Quench Test
Authors: Rontó Viktória , Nagy E. , Svéda Mária , Tomolya Kinga , Varga F. , Molnár B.
Published: March 2009

Copper alloys have many properties, which make them suitable in wide-ranging
applications in all the engineering industries. For the investigated alloys the most important
properties are hardness, strength and electrical conductivity. Precipitation hardenable alloys were
studied by Jominy end-quench test, in order to examine the change of hardness, electrical
conductivity and microstructure as a length of the test bar (i.e. cooling rate). In the first step samples
were solution treated at different temperatures, then water quenched followed by aging. Cold-work
after quench was applied in some alloys and improve in the properties was clearly seen. The
following Cu-alloys were investigated: Cu-Co-Ni-Be, Cu-2Be-Ni and Cu-2Ni-Be.
Preparation of SiC/MoSi2 Composites by Mechanical Alloying and its Fracture Properties
Authors: Wu Hsin Ming , Hu Chia Jung , Chou Ya Hui
Published: March 2009

Ball milling was utilized to make composite powders from either elemental Mo, Si, C
powders or compound MoSi2 and SiC powders. The milled powders were hot-pressed in a vacuum
furnace to produce 10 to 30 vol.% SiC-reinforced MoSi2 composites. The influence of
microstructure on the indentation fracture toughness of the fabricated SiC/MoSi2 composites was
investigated. The SiC particles present in the consolidated compound composite are larger than
those in the elemental composite while the pores observed in the former composite are fewer than
in the latter. The overall values of fracture toughness measured on the compound composites are
higher than those of elemental composites. The major reason for the greater toughness of compound
composites is due to the larger SiC particles and fewer pores in these materials.
Microstructure and Mechanical Properties of Twin-Roll Strip Cast Mg Alloys
Authors: Park Sung S. , Bae Geun Tae , Lee Jung G. , Kang Dae H. , Shin Kwang Seon , Kim Nack
Published: March 2009

Development of wrought Mg alloys, particularly in sheet form, is essential to support the
growing interest for lightweight components in the automotive industry. However, development of
Mg alloy sheets has been quite slow due to the complexity of sheet production originated from limited
deformability of Mg. In this respect, twin-roll strip casting, a one-step processing of flat rolled
products, can be an alternative for the production of Mg alloy sheets. In this study, AZ31 and
experimental ZM series alloys are twin-roll strip cast into 2 mm thick sheets. The microstructure of
the as-cast AZ31 alloy sheet consists of columnar zones near the roll side and equiaxed zones in the
mid-thickness region. On the other hand, as-cast ZM series alloy sheets show equiaxed dendritic
structure through the thickness of sheet. These alloys were subjected to various thermo-mechanical
treatments and their tensile properties were evaluated. Twin-roll strip cast AZ31 alloy in H24
condition has equivalent yield and tensile strengths with similar ductility compared to commercial
ingot cast AZ31-H24 alloy, indicating that twin-roll strip casting is a viable process for the fabrication
of Mg alloy sheets. The experimental ZM series alloys have a large volume fraction of fine dispersoid
particles in the microstructure, resulting from the beneficial effect of twin-roll strip casting on
microstructural refinement. It has been shown that the experimental ZM series alloys have superior
tensile properties compared to commercial ingot cast AZ31-H24 alloy, suggesting the possibility of
the development of new wrought Mg alloy sheets by twin-roll strip casting.
Microstructural Features of Plasma Nitrided Molybdenum Alloy Steel
Authors: Franklin M.J. , Huang S.W. , Chandra Tara , Tieu A. Kiet
Published: March 2009

This research is part of a larger project to investigate the wear and friction of the centre
bearing of a rail freight truck. Existing centre bearing surfaces include flame hardened AISI 1030
steel and AISI 1053 cast steel top centres mating against un-greased and/or greased Hadfield steel
centre bowl liners, and polyethylene centre bowl liners. The wear life of the unlubricated steels
against Hadfield steel is short, greasing the bearings is costly, and industry reports some failures of
polyethylene centre bowl liners due to excessive plastic flow and cracking of the rim wall.
Vacuum Induction Melting and Investment Casting Technologies Tailored to Near-Gamma TiAl Alloys
Authors: Dlouhý Antonín , Dočekalová Kateřina , Zemčík Ladislav
Published: March 2009

The present study focuses on vacuum induction melting and investment casting of neargamma
TiAl intermetallic alloys. The attention is mainly given to a cost-effective melting process in
which a primary alloy ingot is re-melted in a ceramic crucible and cast into a ceramic shell mould.
Two types of crucibles (based on Al2O3 and Y2O3) are considered. The most detrimental reactions
that govern the contamination of the molten alloy with ceramic particles were determined. Results
suggest that the crucible wall attack can be considerably limited by using either the Y2O3 (with no
SiO2-type binder) or Al2O3 crucibles with a suitable coating. After pouring, a mechanical interaction
associated with different thermal expansions of TiAl casts and ceramic shell moulds can result in
serious product damage. A simple 1D-1D model of the cooling process was formulated and the heat
flow as well as stress states in the cast-mould system were numerically solved. Process parameters
(melt superheat, initial mould temperature, cooling kinetics and mould composition) were optimized
in order to reduce the stress in the casts. The optimized parameters delimited a processing window
in which complex-shaped TiAl castings like turbocharger wheels can be fabricated.
A Numerical Model for the Description of Massive and Lamellar Microstructure Formation in Gamma-TiAl
Authors: Jacot Alain , Rostamian Amin
Published: March 2009

A phenomenological modeling approach has been developed to describe the massive
transformation and the formation of lamellar microstructures during cooling in gamma titanium
aluminides. The modeling approach is based on a combination of nucleation and growth laws which
take into account the specific mechanisms of each phase transformation. Nucleation of both massive
and lamellar γ is described with classical nucleation theory, accounting for the fact that nuclei are
formed predominantly at α/α grain boundaries. Growth of the massive γ grains is calculated with a
mathematical expression for interface-controlled reactions. A modified Zener model is used to
calculate the thickening rate of the γ lamellar precipitates. The model incorporates the effect of
particle impingement and rapid coverage of the nucleation sites due to growth. The driving pressures
of the phase transformations are obtained form Thermo-Calc based on actual temperature and matrix
composition. The model permitted investigating the influence of alloy chemistry, cooling rate and
average α grain size upon the amount of massive γ and the average thickness and spacing of the
lamellae. Calculated CCT diagrams were compared with experimental data collected from the
literature and showed good agreement.
Influence of Step Aging on Creep Behavior and Microstructural Evolution of Fine-Grained Fully Lamellar XD TiAl Alloys
Authors: Zhu Han Liang , Seo Dongyi , Maruyama Kouichi , Au Peter
Published: March 2009

Fine-grained fully lamellar (FGFL) structures of XD TiAl alloys (Ti-45 and
47Al-2Nb-2Mn+0.8vol.%TiB2) (at.%) were stabilized to varying degrees by different aging
treatments. Specimens with and without aging were creep tested at 760°C and 207 MPa. It was
found that during creep deformation, degradation of the lamellar structure involving coarsening
within the colonies and spheroidization at colony boundaries occurred, forming fine globular
structures at the colony boundaries and increasing the creep rate. Aging treatments stabilized the
lamellar structure and retarded the coarsening and spheroidization processes during creep
deformation. As a result, the aged specimens exhibited lower minimum creep rates and longer creep
lives than the unaged specimens. A multiple step aging stabilized the lamellar structure to the
greatest extent and suppressed other degradation processes during aging, resulting in the best creep
resistance. These results demonstrate that the multiple step aging is the optimal aging condition for
stabilizing FGFL XD TiAl alloys.
Selected Aspects of Semisolid Forming Magnesium Alloys
Authors: Czerwinski Frank
Published: March 2009

The conventional and novel routes of injection molding magnesium alloys are described,
including thixo- and rheomolding, semisolid extrusion molding, near-liquidus molding, composite
molding and alloy generation by mixing thixotropic slurries. For each technique the basic concepts
along with their experimental verifications are explained. The examples show the universal nature
of the injection molding and its capability of implementing a variety of modern processing methods.
Development of Aluminium Alloys with Ultimate Recrystallisation Resistance
Authors: Hallem Håkon , Forbord Børge , Marthinsen Knut
Published: March 2009

In the present work the precipitation behaviour and recrystallisation resistance of Alalloys
containing Hf, Sc and Zr in different concentrations and combinations have been
investigated. Special focus has been put on the Hf-containing alloys, as one of the objectives of this
work was to find out if Hf can be used as a replacement for Sc. Additions of Sc, either alone or in
combination with Zr, leads to the formation of coherent and homogeneously distributed dispersoids,
which very efficiently inhibit recrystallisation. Despite these attractive properties, the high price of
Sc has limited its use as an alloying element in aluminium. The present investigation has revealed
that Hf cannot fully replace Sc, as only heterogeneous dispersoid distributions are obtained in the
absence of Sc, i.e. in regions where the number density is low the alloys would still be prone to
recrystallisation. However, as an extra addition to the already remarkably stable Sc+Zr-containing
alloys, Hf can lead to further improvements and consequently open for the use of aluminium alloys
at very high temperatures. Al3(Sc,Zr,Hf)-dispersoids were present at the largest f/r-ratios and also
displayed lower coarsening rates than Al3(Sc,Zr)-dispersoids. Very promising results were obtained
for an Al-Hf-Sc-Zr alloy, which maintained mainly an unrecrystallised structure after extrusion and
large degrees of cold rolling.
HRTEM Observation of the Precipitates in Heat-Resistant Mg-Gd-Y-Zr Alloy
Authors: Kawabata Tokimasa , Fukuda Yuya , Matsuda Kenji , Kamado Shigeharu , Kojima Yo , Ikeno Susumu
Published: March 2009

The high resolution transmission electron microscope (HRTEM) observation was
carried out to investigate the microstructure of precipitates in Mg-Gd-Y-Zr alloy. In the
early stage of aging at 423K, monoatomic layers were observed along the (1 1 00)Mg plane.
After 64h aging at 423K, the contrast of β” phase based on ordered D019 hexagonal super
lattice structure was appeared. The monoatomic layers, two layers spaced by (1 1 00) Mg
planes and β’ phase based on bco-structure were observed in the specimen aged for 128h.
In the peak- aged specimen, the β’ phase and monoatomic layers were observed.
Computational Welding Mechanics and Concept of Inherent Strain for Industrial Applications
Authors: Murakawa Hidekazu
Published: March 2009

The distortion and the residual stress are the inevitable consequences of the welding and
these may reduce the strength and the quality of the welded structures. To prevent the harmful
influence of the welding distortion and the residual stress, their theoretical prediction is necessary.
However the existing methods are mostly developed for the study of specimens in laboratories.
Compared to the specimens, the structures manufactured in the industry are larger in size and more
complex in geometry. For the theoretical prediction applicable to industrial structures, more
powerful and practical methods are necessary. To achieve this goal, the authors developed a fast
computational method for thermal elastic plastic analysis and an elastic finite element method using
inherent deformation.
Dynamic Evaluation of Strength-Structure Properties by the Determination of Activation Volume and Mean Slip Distance
Authors: Saimoto Shigeo
Published: March 2009

Measurements of the activation volume and mean slip distance were used in the dynamic
dislocation-defect analysis to reveal the dislocation-obstacle evolution with strain. Due to the large
effect of point defect mobility above 250 K on the strain rate sensitivity, fine-grained Al specimens
with the grain-boundaries sealed and unsealed as vacancy sinks were tested at 300 K as the
reference behaviour. The activation distance diagrams revealed that the artificially aged products in
AA6111 and naturally aged extruded AA6063 can be used to examine the effect of chopping-up of
particles on the ductility of the samples. Thus a means to examine strength-structure-ductility of
specific products have been devised.
Microstructure Analysis of Cold Worked Holes
Authors: Nagaraj Shanmukha , Krishna M.
Published: March 2009

The cold expansion technique is often used to introduce beneficial
compressive residual stresses at fastener holes that retard cracking in fatigue loaded
material. The present investigation emphasizes micro structural changes along the
radial section of holes after the holes are subjected to cold working. The experiment
was conducted for two different materials, namely Steel85, EN-8D alloy steel with
thickness 10mm. The holes are expanded to different percentages by split sleeve
method and the microstructures are observed using SEM (Scanning Electron
Microscope). It is observed from the micrographs that a zone of plastic deformation
close to the hole followed by a zone of elastic compression induced by the split sleeve
expansion. A comparative study of microstructure of the hole before and after
expansion and also study the pattern after different extent of expansion of holes
High Temperature Oxidation of Steel; New Description of Structure and Properties of Oxide
Authors: Szpunar Jerzy A. , Kim Bae Kyun
Published: March 2009

The quality of steel sheets is strongly affected by the surface defects that can be generated
during hot rolling and are often related to scales removal operation. These defects are related to
rather complex high temperature oxidation processes. In order to reduce an occurrence of the
defects, it is necessary to understand better the formation of iron oxides during high temperature
oxidation, the structure of the interfaces with the substrate and between different oxide phases.
However, due to the lack of good experimental research tools details of iron oxide microstructures
were not investigated. Conventional methods, such as backscattered electron images or fractography
can only provide general characteristics of microstructures like grain morphology and grain size.
In this paper the microstructure, phase distribution and texture in oxide formed during high
temperature oxidation of iron and low carbon steels are investigated. The oxide microstructures are
characterized by orientation imaging microscopy (OIM) on the cross-sectional area of the oxide
layers. It is demonstrated that OIM using electron backscattered diffraction (EBSD) techniques, can
be used to distinguish grains having different phase composition and orientation and can become
invaluable tool for visualizing the oxide microstructure, texture and also can be used to study oxide
defects. The three different iron oxides phases can be distinguished and the characteristics of oxides
with different oxidation histories compared The characteristics of high temperature oxidation
microstructure of iron are presented with description of iron oxide defects and cracking as well as
the illustration of the interfacial microstructure between the layered iron oxides.
Phase-Field Modeling of the Microstructure Evolutions in Fe-Cu Base Alloys
Authors: Koyama Toshiyuki , Onodera Hidehiro
Published: March 2009

The phase transformations and the microstructure developments in Fe-Cu base alloys
during isothermal aging are simulated based on the phase-field method. Since the chemical free
energy used in this simulation is obtained from the thermodynamic database of phase diagrams,
the calculated microstructure changes are directly related to the phase diagram of the real alloy
system. Firstly the phase decomposition and the microstructure changes in the Fe-Cu binary alloy
system are demonstrated as the simple example of the phase-field modeling, i.e., the phase
decomposition in bcc phase where the Cu-rich phase forms, the structural phase transformation
from bcc to fcc phase in the Cu-rich nano-particle, and the shape change of fcc-Cu precipitates
from sphere to rod. Secondly, the phase decomposition in bcc phase of the multi-component alloys
such as the Fe-Cu-X (X=Mn,Ni) ternary system and the Fe-Cu-Mn-Ni quaternary alloy is
simulated. At the early stage of aging, the Cu-rich zone with bcc structure begins to nucleate, and
the component X (=Mn, Ni) is partitioned to the Cu-rich phase. When the Cu composition in the
precipitate reaches equilibrium, the component X inside the precipitates moves toward to the
interface region between the precipitate and matrix. Finally, there appears the shell structure that
the Cu precipitates surrounded by the thin layer with high concentration of component X.
Free Energy Calculations of Precipitate Nucleation
Authors: Nishitani Shigeto R. , Seko Atsuto , Yuge Koretaka , Tanaka Isao
Published: March 2009

Our recently proposed calculating method reliably predicts the nucleation free energy
barrier of the homogeneous and coherent precipitations. Helmholtz free energy change is clearly
defined and calculated by the purely enthalpic and entropic contributions between the initial state of
the isolated solute atoms scattering around the matrix and the final state of the cluster of size n
traveling around the matrix. The enthalpic term is calculated by the reliable first principles
method and the entropic term is estimated by the ideal solution model. The vibrational free
energy is also included by the quasi-harmonic approximation. The model calculation was
performed on bcc Cu precipitations in the Fe-Cu system. The predicted values of the critical
number of 12 atoms and the critical free energy barrier of 0.6eV show good agreement with the
experimentally estimated ones for the annealing temperature of 773K and the initial concentration
of 1.4at%Cu.
Abnormal Grain Growth Topology and Kinetics
Authors: Rios Paulo Rangel , Glicksman Martin E.
Published: March 2009

One common point amongst extant theories of abnormal grain growth (AGG) is that they
treat this phenomenon in terms of the relative grain size, or grain radius, of the abnormal grains.
Topological and metrical quantities of abnormal grains, such as the number of their faces, or their
grain boundary curvature, are taken into account only indirectly through the grain size itself. This
paper, by contrast, treats AGG in terms of concepts, that include both the boundary curvature and
the number of faces of the abnormal grain. Two cases are examined: 1) AGG, in which the matrix
grains are fully pinned, so normal grain growth cannot occur; 2) AGG in which the matrix grains
are free to evolve, so that normal grain growth ensues simultaneously in the matrix.
Production of Titanium Nitride by Carbothermic Reduction of the Anatase and Rutile Forms of Titanium Dioxide
Authors: Saidi Ali , Setoudeh N. , Welham Nicholas J.
Published: March 2009

Two types of titanium oxide were used, rutile (>99.9% TiO2) and anatase (>99% TiO2). Both
samples were mixed with graphite in accordance with the required stoichiometry, and then milled in
a tumbling mill for 50 hours in an argon atmosphere to ensure thorough mixing. The mill vial was
loaded with five 25.4 mm diameter stainless steel balls giving a powder to ball mass ratio of 1:43.
After milling, samples were heated to 1400°C in an alumina crucible at 20°C min-1 under a flowing
nitrogen (100 mL min-1) atmosphere in a thermogravimetric analyser (TGA). Srilankite was
detected in the as-milled anatase sample but the anatase to rutile transformation was not completed
during milling. After heating to 800°C most of the anatase had transformed to rutile. Reduction of
anatase started just below 900°C whilst rutile underwent reduction below 800°C. TGA results
showed that the anatase reduction was more complex than the rutile reduction with several stages
evident between 880 and 1000°C in the anatase sample whilst only two steps were observed for
rutile. The initial identified products were Ti5O9 and Ti4O7 prior to TiN in anatase sample but in
rutile sample only Ti4O7 was detected. Reduction was completed in rutile sample before
1180°C whilst in anatase completed at 1230°C. TiN was the final product in both systems after
heating to 1400°C. These results are discussed in light of recent work demonstrating the different
reductions paths of rutile and anatase.
Enhanced Strength and Ductility at a Cryogenic Temperature in a Nanostructured Ni-Fe Alloy
Authors: Li Hong Qi , Tao Kai Xiang , Choo Hahn , Liaw Peter K.
Published: March 2009

The compressive behavior was investigated on an electrodeposited nanocrystalline
Ni-20%Fe alloy with a grain size of about 22 nm at room temperature (RT), 298 K, and the
liquid nitrogen temperature (LN2T), 77 K. The sensitivity of the yield strength and plastic strain
to the test temperature at different grain sizes was discussed. Moreover, through the
Transmission Electron Microscopy (TEM) examination and microhardness measurement, the
microstructures before and after the compression test at RT and LN2T were studied.
Nanostructured Titanium Based Materials
Authors: Matteazzi Paolo
Published: March 2009

Assembling Nanostructures in 3D objects is actually the most relevant challenge in
nanomanufacturing, opening the route to full industrial impact of nanomaterials. Titanium based
systems are of great interest in several applications due to combination of strength, density,
corrosion resistance and biocompatibility. Nanostructured Titanium alloys can be synthesized by
high energy milling and assembled in 3D products by different routes.
Corrosion Behavior of Al-7wt% Si-1.5wt% Cu Severely Deformed by Equal-Channel Angular Pressing
Authors: Zhang Zuo Gui , Akiyama Eiji , Watanabe Yoshimi , Katada Yasuyuki , Tsuzaki Kaneaki
Published: March 2009

In this study, an Al-7 wt% Si-1.5 wt% Cu alloy was subjected to severe plastic
deformation (SPD) by an equal-channel angular pressing (ECAP) technique. The ECAP process
was repetitively carried out up to 8 passes using a strain introduction method of route BC, at a
temperature of 25 °C and a pressing rate of 0.33 mm s-1. Microstructures of the samples before
and after ECAP were observed by a scanning electron microscopy (SEM). Electrochemical
properties of the Al-Si-Cu alloy fabricated by ECAP have been investigated in a borate-boric acid
buffer solution containing Cl¯ ions at pH 8.3 and 25 °C by potentiodynamic polarization test.
Corrosion pits on the sample surface after anodic polarization were investigated by means of SEM.
The anodic polarization showed that as-cast Al-Si-Cu alloy with plate-shaped Si particles has poor
resistance against pitting corrosion comparing to quenched sample without ECAP. Pitting
potentials of ECAPed Al-Si-Cu alloy samples were higher than that of the sample without ECAP.
In the Al-Si-Cu alloy, the corrosion pits were found in the region of Si particles and the size of pits
formed on the ECAPed samples became smaller than that without ECAP. It is considered that the
improvement of the pitting resistance of ECAPed Al-Si-Cu alloy is due to homogenous distribution
of spherical Si particles generated during ECAP process.
Effect of Equal-Channel Angular Pressing (ECAP) on Creep in Aluminium Alloys
Authors: Sklenička Václav , Dvořák Jiří , Kvapilová Marie , Svoboda Milan , Král Petr , Saxl Ivan , Horita Z.
Published: March 2009

This paper examines the effect of equal-channel angular pressing (ECAP) on creep
behaviour of pure aluminium, binary Al-0.2wt.%Sc alloy and ternary Al-3wt.%Mg-0.2wt.%Sc
alloy. The ECAP was conducted at room temperature with a die that had a 90° angle between the
channels and 8 repetitive ECAP passes followed route BC. Constant stress compression creep tests
were performed at 473 K and stresses ranging between 16 to 80 MPa on ECAP materials and, for
comparison purposes, on the initial coarse-grained materials. The results showed that the creep
resistance of the ECAP processed Al-Sc and Al-Mg-Sc alloys was markedly deteriorated with
respect to unpressed coarse-grained materials.
Microstructural Changes in As-Cast 7475 Al Alloy during Warm Sever Forging
Authors: Goloborodko Alexandre , Sakai Taku , Sitdikov Oleg , Miura Hiromi
Published: March 2009

Microstructural changes taking place in an as-cast coarse-grained 7475 Al alloy was
studied by using multidirectional forging (MDF) at a temperature of 250oC and at a strain rate of 3
× 10-4 s-1. The samples were deformed by MDF with a strain of 0.7 per pass up to cumulative strain
(Σε) of 8.4. In the earlier stages of deformation, microstructural changes are mainly characterized
by development of dislocation subboundaries with low-to-moderate misorientation angles. The
misorientation angle initially increases with straining and reaches a plateau of around 3.7o in the
strain range from 0.7 to 2.1, where new grain formation scarcely takes place in the original grain
interiors. With further straining, grain fragmentation starts to occur accompanying with deformation
bands developed at various directions, followed by rapid evolution of a new fine grain structure at
large strain. The average grain size is around 1 μm at large strains and the average misorientation
angle approaches a value of about 25o at Σε = 8.4.
Change of Young's Modulus of Cold-Deformed Aluminum AA 1050 and of AA 2024 (T65): A Comparative Study
Authors: Villuendas A. , Roca Antoni , Jorba Jordi
Published: March 2009

The knowledge of some mechanical properties of materials and their changes with
thermal treatments and/or mechanical treatments are essential to obtain the best results during
simulation of processes. In this paper, changes of Young's modulus at room temperature of colddeformed
aluminum AA1050 carried out in a tension machine and changes of Young’s modulus
and Poisson’s ratio of AA2024 (T6 and T65) have been determined. The elastics constants have
been measured by the ultrasound technique in AA2024 alloy and by tensile test in AA1050. In this
alloy, the Young's modulus (E) diminishes during the first step of deformation and then increases
with the successive cold working. Changes in Young's modulus measured are around 6-8%. In
AA2024, the Young's modulus change is about 3% between the annealed and quenched alloy
(minimum value); during aging the E parameter increases with respect to quenching. These changes
are correlated with the structural changes during thermal treatments. In AA2024, the E parameter
remains almost constant during cold-working after the aging treatment. Poisson’s ratio of this alloy
remains almost constant in all the treatments. These results are also correlated with the dislocations
arrangement in both materials. This behaviour is also compared with cold-deformed pure iron in a
tensile test. These results confirm that aluminum AA1050 present similar behaviour than it was
observed for pure iron.
Superplasticity of Fine-Grained 20VOL%SiC Whiskers Reinforced 2024 Aluminum Alloy Produced by ECAP with a Rotary Die
Authors: Ma Aibin , Nishida Yoshinori , Nagase Masakazu , Jiang Jing Hua , Kim Jin Chun , Saito Naobumi , Shigematsu Ichinori
Published: March 2009

Squeeze-cast 20vol%SiCw/2024 composite was processed by rotary-die equal-channel
angular pressing (RD-ECAP) and tensile-tested at elevated temperatures. RD-ECAP does not
require billet removal and reinsertion between ECAP passes and can produce large cumulative
deformation of type A in the billet at a controlled extrusion temperature. Tensile specimens were
machined from the RD-ECAP processed billets along the longitudinal direction. 16 RD-ECAP
passes at 623 K produced an average matrix grain size of about 0.8 μm in the composite. The ECAP
processed 20vol%SiCw/2024 composite exhibited 330% elongation to failure when tested at 783 K
and the high strain rate of 1.17×10-1 s-1. The values of strain rate sensitivity exponent of the
SiCw/2024 composite determined over the strain rates between 10-2 and 1.0 s-1, was 0.39, 0.47 and
0.53 at 763, 773 and 783 K, respectively. The grain sizes of the aluminum alloy matrix in the
composite after superplastic deformation increased from 0.8 μm to be about 1.5 μm. There was no
cavity found within the uniformly deformed area. The apparent activation energy for the
superplastic deformation of the 20vol%SiCw/2024 composite was determined to be 284 kJ·mol-1.
Texture Evolution during Diffusional Heat Treatment from Roll-Bonded Ti/Ni Laminates to TiNi Shape Memory Alloy Sheets
Authors: Inoue Hirofumi , Asao K. , Ishio Masaaki , Takasugi Takayuki
Published: March 2009

TiNi shape memory alloy thin sheets were produced from titanium and nickel metal sheets
by a new processing consisting of repetitive roll-bonding and diffusional heat treatment. TiNi sheets
after heat treatment at a relatively low temperature for a long time exhibited fairly isotropic and high
shape-recoverable strain, because a near {111} B2-phase texture such as {223}<110> and
{332}<113> was developed through reactive diffusion during heat treatment. In the early stage of
reactive diffusion, intermetallic layers of Ti2Ni, TiNi and Ni3Ti were formed at once at the Ti/Ni
interfaces of the roll-bonded laminate and then growth of a TiNi phase took place with the progress of
interdiffusion. Texture of the final TiNi thin sheets, therefore, is derived from that of TiNi layers
generated at the Ti/Ni interfaces, which is considered to have inherited rolling textures of Ni and Ti
layers in the Ti/Ni laminate prior to reactive diffusion under orientation relationships on close-packed
plane and direction between parent and product phases.
Microstructure and Texture in an Alpha/Beta Titanium Alloy and their Impact on Mechanical Response
Authors: Evans W.J. , Eng F.R.
Published: March 2009

The paper explores texture in the titanium alloys Ti-6-4 and Ti 550. It illustrates how
texture evolves under plane strain compression in Ti-6-4. This evolution is dependent on
temperature, degree of reduction (strain) and strain rate. Rolled (Ti-6-4) and forged (Ti 550)
variants with different textures are then examined under tension and torsion loading in relation to
their monotonic and fatigue response. Correlation of the observations with regard to orientation of
the basal plane is demonstrated.
Control of Grain Size and Texture in Al Alloys Utilizing Friction Stir Processing
Authors: Shibayanagi Toshiya , Naka Masaaki
Published: March 2009

The present paper deals with the control of microstructure of friction stir processed
aluminum alloys focusing on grain refinement, thermal stability at elevated temperature and texture
development in some aluminum alloys such as 5083, 6061 and 7075 commercial aluminum alloys.
3mm thickness plates of 5083, 6061 and 7075 Al alloys were friction stir processed/welded with
several rotation speeds and travelling speeds. Optical microscopy revealed the grain refinement in
the stirred zone of each alloy and the average grain size decreased with decreasing rotation speed
under various travelling speeds. Annealing of the joints brought about abnormal grain growth at
temperatures higher than 773K for 5083 alloy. Critical temperature of the abnormal grain growth
tended to decrease as the rotation speed decreased for the fixed travelling speed. Dissimilar joining
of 5083 Al alloy to 6061 Al alloy also showed abnormal grain growth when annealed at 773K. A
peculiar texture development of 7075 Al joint showing (111)//ND-oriented grains existing
throughout the nugget was revealed by EBSP analysis.
Friction and Wear of Laser Irradiated Amorphous Metals
Authors: Tsujikawa Masato , Azuma Daisuke , Hino Makoto , Kimura Hisamichi , Yubuta Kunio , Inoue Akihisa
Published: March 2009

Tribological properties are found to change with microstructure. In Ni-P amorphous
alloy, annealing conditions were varied with laser irradiation parameters such as scanning speed
and laser power. The increase in hardness affected by scanning speed. A peak of hardness was
observed as the function of scanning speed. This is because, the formation of nanoscopic
composite structure by distribution of crystalline Ni3P compounds in amorphous matrix is the
hardest structure.
Effects of Nitrogen on Weld Metal Microstructure and Toughness in Submerged Arc Welding
Authors: Bang Kook Soo , Kim Woo Yeol , Park Chan , Ahn Young Ho , Lee Jong Bong
Published: March 2009

The effects of nitrogen content on weld metal impact toughness in submerged arc welding
were investigated and interpreted in terms of microstructural changes and solid solution hardening.
The weld metal impact toughness in as-welded condition decreased with increasing nitrogen content
from 110 to 200 ppm. The weld metal microstructure changed with increasing nitrogen content;
ferrite with second phase increased at the expense of tough acicular ferrite. In addition to
microstructural changes, the microhardness of acicular ferrite increased gradually with the nitrogen
content. Therefore, the loss of impact toughness can be attributed to a combination of the effects of
microstructural changes and solid solution hardening.
Steel-to-Aluminum Joining by Control of Interface Microstructures - Laser-Roll Bonding and Magnetic Pulse Welding -
Authors: Marya Manuel , Rathod M.J. , Marya Surendar , Kutsuna Muneharu , Priem Didier
Published: March 2009

Laser-roll bonding and magnetic pulse welding are two relatively new processes
that greatly minimize problems of metallurgical incompatibilities between dissimilar metals
and alloys. These two processes, though technologically apart and invented for components
with distinct geometries, utilize to various extents high pressures to facilitate rapid and
localized interfacial heating and create reliable joints. In this paper, relations between process
parameters, microstructures, and properties are discussed for aluminum-to-steel joints made
by laser-roll bonding and magnetic pulse welding.