bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Post Weld Heat Treatment on the Interface Microstructure of Explosively Welded Titanium/Stainless Steel Composite Clad
Authors: Sartangi Pezhman Farhadi , Mousavi Seiyed Ali Asghar Akbari
Published: March 2009

In this study, the microstructure evolutions of the interface of the explosively welded cp-
Ti/AISI 304 S.S composites due to heat treatment are presented. The composites were subjected to
heat treatment process at various ranges of 650-950°C in argon atmosphere for 1hr. The
investigations were carried out by using optical microscopy (OM), scanning electron microscopy
(SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The results reveal the
presence of reaction layers in the interface and show that heat treatments cause to form different
intermetallic phases at the interface. In addition, it is found that the width of the interfacial layer
increases with temperature. Fractographical studies of the lug-shear test samples show the
formation of river patterns and kirkendal pore structures on the Ti-side of the interface.
Experimental Estimation of Strain Rate during FSW of Al-Alloy Using Plane-Strain Compression
Authors: Masaki Kunitaka , Sato Yutaka S. , Maeda Masakatsu , Kokawa Hiroyuki
Published: March 2009

Friction stir welding (FSW) makes the stir zone with fine recrystallized grain structure.
The recrystallized grains would be formed through dynamic recrystallization at high temperatures
and high strain-rate. The present study experimentally simulated the dynamically recrystallized
microstructure of a friction stir welded Al alloy 1050 produced at 600 rpm rotation and 100
mm/min travel speed, using combination of the plane-strain compression at various strain rates and
the subsequent cooling along the cooling cycle of FSW. The equiaxed grain structures similar to the
microstructure of the stir zone were produced at strain rates between 0.1 and 32 s-1; the grain size
decreased with increasing strain rate. Strain rate during the FSW could be estimated to be about 1.8
s-1. The present study suggests that plane-strain compression test can simulate the recrystallized
grain structure of the friction stir welds.
An Efficient Welding Method to Control the HAZ Softening of Ultra Fine Grained Steel Weldment
Authors: Youn Joong Geun , Park Tae Dong
Published: March 2009

The HAZ softening of the ultra fine grained steel weldment occurs when welding heat
input is higher than the critical value. The critical welding heat input was found to be about 10kJ/cm
for the steel studied. The lowest hardness value and the width of the softened HAZ are dependant
on the applied welding heat input. For obtaining high productivity with the low heat input, less than
10kJ/cm, a high speed FCA welding process with 2 electrodes was developed and verified to be an
efficient method for the ultra fine grained steel. The weldment made by this process did not have
the softened HAZ; and thus, satisfied the tensile strength required.
Selection of the GTAW-Flux Process Parameters on Type 310 Stainless Steel via a Taguchi-Neural Approach
Authors: Lin Hsuan Liang , Chou Chang Pin , Chen Ming Song
Published: March 2009

In order to achieve single pass welds without edge preparation, instead of multipass
procedures, one of the most notable techniques is to use activating flux with GTA welding (GTAWflux)
process. In autogenous GTA welding mixed fluxes (oxide SiO2 and Cr2O3), were applied on
the weld area of type 310 stainless steel through a layer of the flux to produce a bead-on-plate weld.
Many parameters affect the GTAW-flux process quality. The Taguchi method can improve on the
disadvantages of full factorial design. However, in practice, it has certain limitations. In this work, a
Taguchi-Neural approach (Combine Taguchi method and a neural network) was used to select the
GTAW-flux process parameters. The experimental procedure of GTAW-flux process, via the
proposed approach produced full penetration of the weld root in 8 mm thick type 310 stainless steel
with single pass welds.
Laser-Arc Hybrid Welding Process of Galvanized Steel Sheets
Authors: Matsusaka Souta , Uezono Toshiro , Tsumura Takuya , Tanaka Manabu , Watanabe Takehiro
Published: March 2009

Galvanized steel sheets with a lap joint were welded by a laser-arc hybrid process. The
hybrid system consisted of 2kW LD or YAG laser oscillator and frequency-modulated DC pulsed
MAG welding machine. In this experiment, the arc traveled on the specimens, following the laser
beam with the interval of 2 mm. The results showed that the hybrid process had some advantages,
such as deep penetration depth, high welding speed and high gap-tolerance, in comparison with the
conventional MAG welding. Observations from a high-speed digital video-camera suggested that
the zinc and iron vapors induced by laser beam irradiation stabilized the arc plasma. Effects of the
incidence angle between a welding head and a specimen on the weld bead formations were also
discussed. As a result, the welding speed of 2.0 m/min was achieved at 1.0 mm of gap length
condition when the incidence angle was 50 degree.
Numerical Analysis of Distortion of a Laser Welded Thin Metal Structure
Authors: Kim Jae Woong , Kim Choong Gi
Published: March 2009

The welding process, incorporating rapid heating and cooling, generates distortion and
residual stress in weldments. Prediction and control of the thermal distortion is particularly
important for the design and manufacture of welded thin plate panel. This study aims to develop a
thermal elasto-plastic simulation using finite element method to predict distortion, with particular
emphasis on buckling deformation generated in a thin metal panel structure welded around hole. In
addition, experiments and computations are performed to analyze how hole configuration and the
size of the specimen effect distortion.
Laser Welding of Dissimilar Sheath Metals
Authors: Kim Soo Sung , Park Geun Il , Koh Jin Hyun
Published: March 2009

This work was carried out to obtain sound welds and to select the most suitable binary
metal joint among three different dissimilar metal combinations such as Zr-4/Ta, Mo/Ta and Ti/Ta
(seal tube/sensor sheath) joints for an instrumented nuclear fuel irradiation test. To do this, the
Taguchi experimental method was employed to optimize the experimental data. In addition,
metallography, micro-focus x-ray radiography and a hardness test were conducted to examine the
welds. From the weld bead appearance, penetration depth and bead width as well as the weld
defects standpoint, the Zr-4/Ta joint is suggested for a circumferential joining between a seal tube
and a sensor sheath. The optimized welding parameters based on the Zr-4/Ta joint are suggested as
well.
Laser-Based Fe-36%Ni (Invar®) Alloy Processing with Deep Microgrooves in Aqueous Solutions
Authors: Oh Kwang H. , Jeong Sung Ho
Published: March 2009

The micromachining technique for the fabrication of Fe-36%Ni (Invar®) microgrooves
using a novel laser-induced wet etching system with an optical fiber as the light waveguide and
machining tool is investigated. Microgrooves fabricated at the optimal process conditions with the
proposed etching system have good surface morphology and dimensional accuracy. It is shown that
the variation of etch profiles such as etch width and depth depends significantly upon the process
parameters. Fiber damage, which is attributed to macrobubbles, can be dramatically reduced by
adjusting the distance between the workpiece surface and the fiber terminal. The effects of process
parameters such as laser power, scan speed, and threshold distance on etch width, depth, and crosssectional
profiles are reported and the optimal process conditions to fabricate Invar® microgrooves
with excellent shape and size are provided. Also, the applicability of the Invar® microgrooves for
the manufacturing of shadow mask for an organic light emitting diode (OLED) is demonstrated.
Development of a LASER Welding Apparatus and a Method for an Inner-Strap Welding of a Spacer Grid Assembly for a PWR Fuel Assembly
Authors: Song Kee Nam , Kim Soo Sung , Lee Soo Bum , Kim Yong Wan
Published: March 2009

A spacer grid assembly, which is an interconnected array of slotted grid straps welded at
the intersections to form an egg crate structure, is one of the core structural components for the
nuclear fuel assemblies of a Pressurized light Water Reactor (PWR). The commercial spacer grid
assembly is spot-welded at the crossing points of the intersections by a TIG welding, LASER beam
welding or Electron beam welding method. In this study, a LASER beam welding apparatus and a
method for an inner strap welding has been proposed to obtain a longer and finer weld line and a
smaller weld bead size for a spacer grid assembly for a PWR fuel assembly. Also a rapid welding
and excellent weld quality have been achieved by the proposed welding apparatus and method.
Statistical Process Monitoring System for SMT Industry Using Automatic Optical Inspection System
Authors: Kim Hee Y. , Han Seung Soo , Hong Sung Bok , Hong Sang Jeen
Published: March 2009

As the demand of higher throughput in high volume surface mounting technology (SMT)
industry, inspection and testing have been notably emphasized. To alleviate concerns associated
with board level soldering inspection, automatic optical inspection (AOI) has been actively used in
SMT industry [1]. In this paper, statistical quality control method has been applied for board level
inspection to maximize the performance of a commercially available AOI system. Considering its
complication of SMT assembled board, implementing the quality control scheme for the measured
variable data is fairly expensive. However, the proposed system efficiently utilizes both attribute
and variable data collected for the daily/weekly based production yield reports, and further utilize as
a method for in-line diagnostics in SMT manufacturing process.
Shape Memory Alloys: A Summary of Recent Achievements
Authors: Entel Peter , Buchelnikov Vasiliy D. , Gruner Markus E. , Hucht Alfred , Khovailo Vladimir V. , Nayak Sanjeev K. , Zayak Alexey T.
Published: March 2009

The Ni-Mn-Ga shape memory alloy displays the largest shape change of all known
magnetic Heusler alloys with a strain of the order of 10% in an external magnetic field of
less than one Tesla. In addition, the alloys exhibit a sequence of intermediate martensites
with the modulated structures usually appearing at c/a < 1 while the low-temperature non-
modulated tetragonal structures have c/a > 1. Typically, in the Ni-based alloys, the martensitic
transformation is accompanied by a systematic change of the electronic structure in the vicinity
of the Fermi energy, where a peak in the electronic density of states from the non-bonding Ni
states is shifted from the occupied region to the unoccupied energy range, which is associated
with a reconstruction of the Fermi surface, and, in most cases, by pronounced phonon anomalies.
The latter appear in high-temperature cubic austenite, premartensite but also in the modulated
phases. In addition, the modulated phases have highly mobile twin boundaries which can be
rearranged by an external magnetic field due to the high magnetic anisotropy, which builds up
in the martensitic phases and which is the origin of the magnetic shape memory effect. This
overall scenario is confirmed by first-principles calculations.
Modeling and FEM Simulation of Shape Memory Microactuators
Authors: Krevet Berthold , Kohl Manfred
Published: March 2009

This article reports on two models for the shape memory effect and explains, how they
are implemented in a finite element method program. The first model uses a phenomenological
approach. For the example of a microgripper, the performance prediction of real actuators made of
polycrystalline materials is demonstrated. In the second model, the martensite-austenite phase
transition is treated as a thermodynamically activated process. Thermodynamic laws, like e.g. the
minimization of the Gibbs free energy, are used for the formulation. To simplify the model, it is
primarily intended to describe the behavior of single crystals. By comparing the simulated bending
characteristic of a cantilever beam with experimental data, the applicability to polycrystalline
material is tested. Due to the physics based formulation, this model gives more insight into the
structural processes involved. This is very useful, e.g., for physical extensions needed for the
simulation of the magnetic shape memory effect. It is shown, how the model can be extended to
predict the behavior of actuators made of ferromagnetic Ni-Mn-Ga single crystals in a magnetic
field.
Control of Crystallographic Orientation and Grain Refinement in Bi2Te3-Based Thermoelectric Semiconductors by Applying High Pressure Torsion
Authors: Ashida Maki , Hamachiyo Takashi , Hasezaki Kazuhiro , Matsunoshita Hirotaka , Kai Masaaki , Horita Z.
Published: March 2009

Prepared were p-type Bi2Te3-based thermoelectric semiconductors, having a
grain-refined microstructure and a preferred orientation of anisotropic crystallographic structure.
Disks with a nominal composition Bi0.5Sb1.5Te3.0 were cut from an ingot grown by the vertical
Bridgman method (VBM) and deformed at 473 K under a pressure of 6.0 GPa by high pressure
torsion (HPT). The crystal orientation was characterized with X-ray diffraction. The
microstructures were characterized by using optical microscopy and scanning electron
microscopy. It was found that the HPT disks had a fine and preferentially oriented grain compared
to that of the VBM disks. Further, the power factor of the HPT disks was about twice as large as
that of the VBM disks. These results indicate that HPT is effective for improving the
thermoelectric properties of Bi2Te3-based thermoelectric semiconductors.
Diffusion in Ultrafine Grained Materials
Authors: Divinski Sergiy V. , Wilde Gerhard
Published: March 2009

The paper provides an overview of recent results of the radiotracer investigations of
short-circuit diffusion in ultra fine grained (UFG) materials produced by severe plastic deformation
(SPD). Different material classes (copper of different purity levels and Cu alloys) are considered.
The study is focused on the existence of non-equilibrium grain boundaries after SPD. Although a
dominant contribution of common high-angle grain boundaries with very similar diffusivities as
those in the corresponding coarse-grained material is established, much faster diffusion rates are
also observed experimentally. The nature and kinetic properties of these “high mobility” paths in
different materials are investigated and critically discussed.
Finite Element Investigation of the Effect of Hardening Behavior of Alloys on Equal Channel Angular Pressing Performance
Authors: Karpuz Pınar , Şimşir Caner , Gür C. Hakan , Kim Hyoung Seop
Published: March 2009

In most of the simulation studies of equal channel angular pressing (ECAP) it has been
assumed that materials obey isotropic hardening law. However, in the case of precipitation
hardenable alloys, an accurate prediction of the deformation behavior requires incorporation of
kinematic hardening model. In this study, the influences of kinematic, isotropic and combined
hardening laws on deformation behavior have been investigated. For this purpose, an ECAP die
consisting of two 120° channels has been selected, and the effect of hardening law on the strain
profile and ram pressure at the final exit channel has been studied. The simulation results showed
that the hardening mechanism does not affect the strain profiles extensively; but, when kinematic
hardening mechanism was considered the ram pressure decreases significantly due to less hardening
of the material during reverse loading in the final exit channel.
Comparative Possibilities of Different X-Ray Methods by Study of SPD Metal Materials
Authors: Isaenkova Margarita , Perlovich Yuriy , Fesenko Vladimir , Krymskaya Olga
Published: March 2009

Possibilities of X-ray methods, using diffractometric measurements of X-ray line profiles
and crystallographic texture, are compared as applied to study of SPD metal materials. The texture
analysis gives the most direct data on the degree of grain fragmentation under conditions of
deformation. The consideration is illustrated by results, obtained by X-ray studies of ECAP rods
from Cu and Ti.
Optical Strain Measurement on Small Specimens Based on Laser Speckles
Authors: Schenuit Eduard , Bolkart Rainer , Becker Thomas , Spinka Oliver
Published: March 2009

Progresses in developments of high resolution digital cameras and processors power as
well enable the use of optical systems for axial and biaxial strain measurements. The main benefit
of these systems is a contact free measurement on the sample surface without any influence to the
sample. The commonly used optical systems based on following markings attached to sample
surface which have to be applied before testing. This paper presents an alternative optical measuring
system using the speckle-correlation-technique. The laser based method does not need any special
sample markings before testing. The speckle correlation in the presented extensometer measures up
to two-dimensional surface strains in tensile as well as in compression tests; original gauge lengths
down to 1.5 mm are supported.
Texture Evolution of Magnesium Single Crystals Deformed by High-Pressure Torsion
Authors: Bonarski Bartlomiej J. , Schafler Erhard , Mikułowski Borys , Zehetbauer Michael J.
Published: March 2009

Single crystals of technical purity Magnesium (99.8 wt.%) of initial orientations [ ] 2 1 10
and [ ] 2 2 11 were subjected to HPT deformation at room temperature up to strains of 10. The
microstructural evolution has been analyzed by X-ray microtexture investigations and by in-situ
stress-strain measurements. The results can be described in terms of shear arising from HPT
deformation and - with higher strains - in terms of recrystallization. In crystals with hard
orientation[ ] 2 2 11 , these features occur at smaller strains than in crystals with soft orientation
[ ] 2 1 10 , i.e. with higher symmetry. In general, the observed textures and strength variations are
much stronger than those reported for fcc HPT deformed metals.
Specific Features of Static, Impact, and Fatigue Fracture of the 0.09%C-0.08%Mo-0.03%Nb-0.06%V Steel with Ultrafine-Grained Structure
Authors: Botvina L.R. , Tyutin Marat R. , Levin V.P. , Demina Y.A. , Panteleev I.A. , Dobatkin Sergey V.
Published: March 2009

The mechanical properties and fracture mechanisms of the 0.09%C-0.08%Mo-0.03%Nb-
0.06%V steel in the initial state and with the ultrafine-grained (UFG) structure obtained by equalchannel
angular pressing (ECAP) have been estimated. The investigation included the static and
cyclic tensile tests, the impact tests at room and lower temperatures with automatic recording of
force-displacement diagram, and the analysis of both the fracture surface microrelief and the
evolution of plastic deformation zone by replica method. It is established that the grain refinement
increases the ultimate strength and yield strength, but decreases plasticity and impact toughness and
raises fatigue growth rate and the critical temperature of ductile–brittle transition. The dynamic
fracture toughness of the material after ECAP as compared with that of the material with the initial
structure decreases due to the raising of the critical brittleness temperature.
Analysis of the Fundamental Mechanisms and Efficiency of the Deformation Methods of Nanostructuring
Authors: Mulyukov Radik R. , Nazarov Ayrat A. , Imayev Renat M.
Published: March 2009

Deformation methods of nanostructuring (DMNs) of materials are proposed to classify
into severe plastic deformation (SPD) and mild plastic deformation (MPD) methods according to
fundamentally different low- and high-temperature grain refinement mechanisms they exploit. A
general analysis of the fundamentals and nanostructuring efficiency of three most developed DMNs,
high pressure torsion (HPT), equal-channel angular pressing (ECAP), and multiple isothermal
forging (MIF) is done with a particular attention to ECAP and MIF. It is demonstrated that MIF is
the most efficient method of DMNs allowing one to obtain the bulkiest nanostructured samples with
enhanced mechanical properties.
Factors Influencing the Development of Homogeneity in Disks Processed by High-Pressure Torsion
Authors: Xu Cheng , Zhilyaev Alexandre P. , Horita Z. , Langdon Terence G.
Published: March 2009

High-pressure torsion (HPT) is an important processing technique in which a disk is
subjected to a high pressure with concurrent torsional straining. In principle at least, the imposed
strain is zero at the center of the disk and a maximum at the outer edge. This difference suggests,
therefore, that materials processed by HPT will exhibit considerable inhomogeneity. This paper
describes the results obtained in a series of experiments which were designed to evaluate the
evolution of homogeneity during the processing of two materials by HPT. It is demonstrated that it
is possible to achieve a reasonable level of homogeneity in both materials but there are important
differences which reflect the dependence of the microstructure on the occurrence of dynamic
recovery.
Grain Refinement of Pure Copper by ECAP
Authors: Lugo Nayar , Cabrera Jose María , Llorca-Isern Nuria , Luis-Pérez C.J. , Luri Rodrigo , León Javier , Puertas Ignacio
Published: March 2009

Pure commercial Cu of 99,98 wt % purity was processed at room temperature by Equal-
Channel Angular Pressing (ECAP) following route Bc. Heavy deformation was introduced in the
samples after a considerable number of ECAP passes, namely 1, 4, 8, 12 and 16. A significant grain
refinement was observed by transmission electron microscopy (TEM). Tensile and microhardness
tests were also carried out on the deformed material in order to correlate microstructure and
mechanical properties. Microhardness measurements displayed a quite homogeneous strain
distribution. The most significative microstructural and mechanical changes were introduced in the
first ECAP pass although a gradual increment in strength and a slight further grain refinement was
noticed in the consecutive ECAP passes.
Ultimate Strength of a Tungsten Heavy Alloy after Severe Plastic Deformation at Quasi-Static and Dynamic Loading
Authors: Meyer Lothar W. , Hockauf Matthias , Hohenwarter Anton , Schneider Steffen
Published: March 2009

A tungsten heavy alloy (92%W, Ni-Co matrix) is subjected to severe plastic deformation
(SPD) by high pressure torsion (HPT) at room temperature up to equivalent strains of 0.7, 5.3, 10.7
and 14.3. The microstructure and the mechanical properties are investigated by cylindrical
compression samples at quasi-static and dynamic loading. The harder spherical W particles are
homogeneously deformed within the softer matrix, becoming ellipsoidal at medium strains and
banded at high strains without shear localization or fracture. Results of quasi-static loading show
that the strength is approaching a limiting value at strains of ~10. At this strain for the matrix a grain
size of ~80 nm and for W a cell size of ~250 nm was observed, suggesting strain concentration on
the matrix. The initial yield stress of 945 MPa for the coarse-grained condition is increased thereby
to an ultimate value of 3500 MPa, while a peak stress of ~3600 MPa is reached. Such remarkably
strength has never been reported before for pure W or W-based composites. The strain hardening
capacity as well as the strain rate sensitivity is reduced drastically, promoting the early formation of
(adiabatic) shear bands.
The Evolution of Homogeneity during Processing of Commercial Purity Aluminium by ECAP
Authors: Alhajeri Saleh N. , Gao Nong , Langdon Terence G.
Published: March 2009

Billets of a commercial purity aluminium Al-1050 alloy were processed by equal-channel
angular pressing (ECAP) for up to a maximum of 6 passes. Following processing, the billets were
sectioned and hardness measurements were recorded on both longitudinal and transverse sections.
These measurements showed the hardness increases significantly in the first pass and continues to
increase by small amounts in subsequent passes. Initially, there are regions of lower hardness
running in bands near the top and bottom surface of each billet. The region of lower hardness near
the upper surface disappears with increasing numbers of passes but near the bottom surface the
lower hardness remains even after 6 passes. The results show that, neglecting the small region near
the bottom of the billet, there is an excellent potential for achieving microstructural homogeneity
within the Al-1050 alloy after pressing through a sufficient number of passes in ECAP.
Influence of Severe Thermomechanical Treatment on Formation of Nanocrystalline Structure in Ni 718 and Ni 718Plus Alloys and their Mechanical Properties
Authors: Mukhtarov Shamil Kh. , Valitov Vener , Gigliotti M.F.X. , Subramanian P.R. , Marte J.S. , Dudova Nadya
Published: March 2009

The influence of severe thermomechanical treatment via multiple forging on the
formation of a nanocrystalline (NC) structure in bulk samples of Alloy 718 and ATI 718Plus has
been investigated. It was observed that a step-wise decrease of processing temperature from 950
down to 575°C allowed the refinement of the initial coarse grain structure to a NC state.
Investigations of structural changes in the deformed samples have shown that extending the
temperature interval of dynamic recrystallization to low homologous temperatures resulted in the
formation of a fine-grained recrystallized structure. The temperature of NC structure formation in
ATI Alloy 718Plus was 50-100°С higher than that required for alloy 718. This was due to the
presence of the additional γ′-phase, which increased the recrystallization temperature. This
decreased the total strain required to produce NC structure, as compared with Alloy 718. It was
observed that increasing the total strain and decreasing temperatures step-wise during deformation
via multiple forging resulted in a uniform structure across the cross-section of the samples. The
room temperature mechanical properties of the investigated alloys with various grain sizes are also
compared.
Mechanical Behavior and Stress-Induced Martensitic Transformation in Nanocrystalline Ti49.4Ni50.6 Alloy
Authors: Prokofiev Egor , Gunderov Dmitriy , Lukyanov Alexander , Pushin V.G. , Valiev Ruslan
Published: March 2009

Amorphous-nanocrystalline Ti49.4Ni50.6 alloy in the shape of a disc 20 mm in diameter
has been successfully produced using high pressure torsion (HPT). Application of HPT and
annealing at temperatures of 300–550°C resulted in formation of a nanocrystalline (NC) structure
with the grain size (D) about 20–300 nm. The HPT samples after annealing at Т = 400°C with the
D= 20 nm possess high yield stress and high ultimate tensile strength (more than 2000 MPa). There
is an area of strain-induced transformation B2-B19’ on the tensile curve of the samples with the
grain size D =20 nm. The stress of martensitic transformation (σm) of samples is 450 MPa, which is
three times higher than σm in the initial coarse-grained state (σm ≈ 160 MPa). The HPT samples
after annealing at Т = 550°C with the D= 300 nm possess high ductility (δ>60 %) and high ultimate
tensile strength (about 1000 MPa).
Effect of Pre-Aging on the Microstructure and Strength of Supersaturated AlZnMg Alloys Processed by ECAP
Authors: Nguyen Quang Chinh , Gubicza Jenő , Czeppe Tomasz , Lendvai Janos , Hegedűs Zoltán , Xu Cheng , Langdon Terence G.
Published: March 2009

This work is focused on the effect of the combination of natural aging and severe plastic
deformation (SPD) produced by Equal-Channel Angular Pressing (ECAP) on the microstructure and
strength of supersaturated AlZnMg alloys. Following a solution heat-treatment and quenching into
water at room temperature, samples were naturally aged for different time periods and then
processed by ECAP. The microstructure and mechanical properties of these samples are described
and discussed. This investigation leads to proposing an interesting application of ECAP for
supersaturated alloys. Using the shear bands created by ECAP in only one pass and applying
appropriate subsequent aging treatments, composite-like microstructures can be achieved in
conventional age-hardenanble Al alloys.
Texture Gradient in a Single Pass ECAPed Pure Mg by Neutron Radiation
Authors: Gan Wei Min , Brokmeier Heinz Günter , Chang Hai , Zheng Ming Yi , Wu Kun
Published: March 2009

Single pass ECAP of pure Magnesium was performed and stopped after 50 %
deformation; textures thereafter at the ingoing, the deformation and the outgoing channel were
characterized by neutron radiation and related to the deformation mode. A gradient texture
evolution was obtained, which was attributed to the inhomogeneous distribution of the effective
stress and strain, and also the inevitable existence of friction.
Microstructure and Properties of Aluminium Processed by Constrained Groove Pressing
Authors: Zrník Jozef , Kovarik Tomas , Cieslar Miroslav
Published: March 2009

In this study, the relationship between the structure and properties of commercial purity
aluminium (AW-1199) was investigated by applying constrained groove pressing (CGP) method.
The refinement of the coarse grain aluminium microstructure to submicrocrystalline size by large
plastic strain at room temperature defined. The impact of various strains upon microstructure
changes is investigated using transmission electron microscopy (TEM) and electron back scatter
diffraction (EBSD). A mixture of subgrains produced by grains subdivision and polygonized
subgrains formed locally due to dynamic recovery was found in the deformed aluminium. The
tensile properties and resulting hardness are related to microstructural evolution induced by CGP. A
substantial impact of straining upon the increasing in tensile strength was observed after the first
pass. Further strain increase had an insignificant effect on tensile strength but was accompanied by
ductility loss. The post deformation annealing effect was then explored with aim to increase the
ductility. The results indicate that changes in strength and ductility may be related to formation of a
bimodal structure.
Particle Redistribution and Grain Refinement during Processing by Hydrostatic Extrusion
Authors: Wawer Kinga , Lewandowska Małgorzata , Kurzydlowski Krzysztof Jan
Published: March 2009

In this study particle redistribution and grain size refinement induced by hydrostatic
extrusion (HE) have been studied in two Al-Si cast alloys (Al-9%Si and Al-11%Si). It has been
found that HE results in a significant changes in particle shape, size and distribution which was
revealed by SEM observations and quantified using stereological parameters. At the same time,
significant grain refinement down to ~100 nm in diameter takes place in aluminium phase. Such a
microstructure evolution affects substantially the mechanical properties of two-phase alloys. The
yield strength and tensile strength increase over two times whereas the plasticity only slightly
decreases.
High Pressure Torsion of Intermetallic Zr3Al
Authors: Geist David , Rentenberger Christian , Karnthaler Hans Peter
Published: March 2009

The L12-structured intermetallic compound Zr3Al can be rendered amorphous easily by
several techniques. In the present study the structural evolution during high pressure torsion (HPT)
was investigated systematically by transmission electron microscopy (TEM) methods. Zr3Al
samples were deformed at room temperature to different grades of deformation up to shear strains
of 140 000%. TEM investigations revealed that the tendency to grain fragmentation, disordering
and the formation of a nanocrystalline structure is weak compared to other L12 ordered alloys like
Ni3Al. In addition, an amorphous phase has not been encountered. The present results differ
strongly from previous ones obtained from ball-milled materials. Possible reasons for the different
behavior are discussed on the basis of the temperature dependent dissociation scheme of the
superlattice dislocations gliding in Zr3Al.
Severe Plastic Deformation of a Bainitic Rail Steel
Authors: Hohenwarter Anton , Stock Richard , Pippan Reinhard
Published: March 2009

Severe Plastic Deformation (SPD) is known to be an effective method of producing
nanocrystalline materials, for instance by HPT and ECAP. These techniques are also capable of
reproducing microstructures which arise naturally when high pressure and friction is involved, for
example in wheel-rail contact problems. The resulting deformation layers build the origin point for
fatigue cracks. For that reason the knowledge of the mechanical properties of these deformation
layers are of vital importance. In the framework of this study a baintic rail steel quality was
deformed by High Pressure Torsion up to distinctive equivalent strains at a nominal pressure of 6
GPa up to a final equivalent strain of 16. Afterwards the evolution of the resulting microstructure
was investigated by Scanning Electron Microscopy, by microhardness measurements and X-ray
diffraction. The bainitic structure showed a strong alignment and fragmentation into the shear
direction with increasing strain, which was accompanied by an increase in hardness as well. X-ray
diffraction measurements showed that the amount of retained austenite decreases dramatically after
small amounts of strain, which indicates that retained austenite cannot be stabilized by high
pressures. Torque measurements during deformation showed after strong hardening at the
beginning, a saturation behaviour for higher strains, whereas for instance pearlitic rail steel qualities
show further hardening.
Microstructure and Mechanical Properties Affecting Crack Growth Behaviour in AA6060 Produced by Equal-Channel Angular Extrusion
Authors: Meyer Lothar W. , Sommer Kristin , Halle T. , Hockauf Matthias
Published: March 2009

Crack growth in AA6060 after two and eight equal-channel angular extrusions (ECAE),
showing a bimodal microstructure and a homogenous ultrafine-grained microstructure, respectively,
are compared to the coarse grained counterpart. Furthermore, an optimized condition, obtained by
combining one ECA-extrusion and a subsequent short aging treatment is included. Fatigue crack
growth behaviour in the near-threshold regime and the region of stable crack growth is investigated
and related to microstructural features such as grain size, grain size distribution, grain boundary
characteristics and ductility. Micrographs of crack propagation surfaces reveal information on crack
propagation features such as crack path deflection and give an insight to the underlying
microstructure. Instrumented Charpy impact tests are performed to investigate crack initiation and
propagation under impact conditions. Due to the recovery of ductility during the post-ECAE heat
treatment, the optimized condition shows improved fatigue crack properties and higher energy
consumption in Charpy impact tests, when compared to the as-processed conditions without heat
treatment.
Martensitic Transformations and Functional Stability in Ultra-Fine Grained NiTi Shape Memory Alloys
Authors: Burow Juri , Prokofiev Egor , Somsen Christoph , Frenzel Jan , Valiev Ruslan , Eggeler Gunther F.
Published: March 2009

Martensitic transformations in NiTi shape memory alloys (SMAs) strongly depend on the
microstructure. In the present work, we investigate how martensitic transformations are affected by
various types of ultra-fine grained (UFG) microstructures resulting from various processing routes.
NiTi SMAs with UFG microstructures were obtained by equal channel angular pressing, high
pressure torsion, wire drawing and subsequent annealing treatments. The resulting material states
were characterized by transmission electron microscopy and differential scanning calorimetry
(DSC). The three thermomechanical processing routes yield microstructures which significantly
differ in terms of grain size and related DSC chart features. While the initial coarse grained material
shows a well defined one-step martensitic transformation on cooling, two-step transformations were
found for all UFG material states. The functional stability of the various UFG microstructures was
evaluated by thermal cycling. It was found that UFG NiTi alloys show a significantly higher
stability. In the present work, we also provide preliminary results on the effect of grain size on the
undercooling required to transform the material into B19’ and on the related heat of transformation.
The Effect of Texture on the Fatigue Properties of Ultrafine-Grained Interstitial-Free Steel
Authors: Niendorf Thomas , Marten Thorsten , Maier Hans J. , Karaman Ibrahim
Published: March 2009

The present paper reports on the effect of texture on the cyclic stress-strain response
(CSSR) and the fatigue life of ultrafine-grained (UFG) interstitial-free (IF) steel. Tests in the lowcycle
fatigue (LCF) regime were conducted on material that was processed by the equal channel
angular extrusion (ECAE) technique along the so called “efficient” route 8E. This route has been
shown to result in a homogeneous microstructure with a high fraction of high angle grain
boundaries (HAGBs), which are beneficial for a stable CSSR. In addition, the evolution of the
microstructure was characterized by means of electron optical techniques, including electron
backscattered diffraction, and by X-Ray diffractometry. It was found that the initial texture of
specimens cut from the ECAE billet along different orientations with respect to the extrusion
direction (ED) has a substantial effect on the CSSR of the UFG IF steel. Furthermore, microscopy
results indicated the notable influence of the last ECAE processing step on the evolution of damage
in the material.
R&D of NanoSPD Materials in Ufa via International Cooperation
Authors: Reshetnikova Tasha , Salakhova Milyausha R. , Safargalina Zarema A. , Shcherbakov Andrey V.
Published: March 2009

This report presents main achievements of international R&D activities of the Institute of
Physics of Advanced Materials of Ufa State Aviation Technical University (Ufa, Russia) with a
special attention to the innovative potential of nanostructured metals and alloys produced by severe
plastic deformation techniques. Several examples of the first promising applications of bulk
nanostructured materials as well as potential competing technologies are considered and discussed.
Continuous Recrystallization Phenomenon in High Purity Copper during Equal Channel Angular Pressing up to High Strain at Room Temperature
Authors: Wang Jing Tao , Zhang Yue , Liu Jin Qiang
Published: March 2009

Equal channel angular pressing (ECAP) was conducted at room
temperature to a high strain level of ~24 in high purity copper. Tensile testing,
Transition Electron Microscopy (TEM) and Electron backscatter diffraction (EBSD)
were used to characterize the microstructure and property evolution with the increase
of ECAP strain. It was found that tensile yield strength and the stored energy
increases upon ECAP processing until a peak reached at 8~12 passes of ECAP, and
their saturation was observed at higher ECAP passes. Continuous recrystallization
phenomenon in microstructure was observed, where dislocation free crystallites with
large misorientation to their surrounding matrix and smaller than the nuclei for
discontinuous recrystallization were observed embodied in the matrix of deformed
structure with high dislocation density. A two-step process was observed for the
formation of these small crystallites, first the condensing of dislocation tangles into a
narrow boundary, mostly low angle boundary; And second local migration (in
sub-micrometer range) of short grain boundaries, in strong contrast to the dramatic
migration of long large angle grain boundaries during discontinuous recrystallization
to swallow the deformed matrix, was observed leading to vanish of small subgrains.
Martensitic Transformation in Fe-Ni Alloys Nanostructured by Ball Milling
Authors: Tcherdyntsev Victor V. , Abdulhalikov S.M. , Kaloshkin S.D. , Pustov Leonid Y. , Estrin E.I. , Zagainov A.V.
Published: March 2009

Fe86Ni14 powder was prepared by mechanical alloying of elemental powders in a highenergy
planetary ball mill. X-ray diffraction was used to investigate structure and phase constitution
of samples, and thermomagnetic measurements were used to study phase transformation
temperatures. MA led to formation of bcc α-Fe and fcc γ-Fe based solid solutions. Significant
reduction of martensitic points for MA alloys was observed that was attributed both to
nanocrystalline structure formation and samples impurity at milling.
Recrystallization in Nanostructured Austenitic Stainless Steel
Authors: Krawczynska Agnieszka T. , Lewandowska Małgorzata , Kurzydlowski Krzysztof Jan
Published: March 2009

Recrystallization and grain growth were studied in an austenitic stainless steel 316LVM
processed by hydrostatic extrusion (HE) to a total true strain of 2. HE processing produces in this
material the microstructure which consists of nanoscale twins on average 19 nm in width and 168
nm in length. The samples after HE were annealed at various temperatures for 1 hour. The structural
changes were investigated using TEM.
The heat induced changes in nanotwinned austenitic steel are significantly different when
compared to the ones in a conventionally deformed material. Microstructural changes take place at
lower annealing temperature. Annealing at 600°C brings about a partial a nanostructure
reorganization into nanograin of average size 54 nm. An uniform microstructure with nanograins of
68 nm in equivalent diameter was obtained after annealing at 700°C whereas conventional 316LVM
steel fully recrystallizes after annealing at 900°C for 1h. Annealing at higher temperatures results in
grain growth.
Effects of Processing Routes on Wear Property of Al-Al3Ti Alloys Severely Deformed by ECAP
Authors: Sato Hisashi , El Hadad Shimaa , Sitdikov Oleg , Watanabe Yoshimi
Published: March 2009

Al-Ti alloys, which have Al3Ti platelet particles in Al matrix, were deformed by ECAP
with routes A and Bc. With increasing the number of ECAP passes, Al3Ti platelet particles are
fragmented and their sizes decrease. The microstructure of ECAPed Al-Ti alloy specimens by route
A has a strong alignment of the fragmented Al3Ti particles. On the other hand, ECAPed Al-Ti alloy
specimens by route Bc have a relatively homogeneous distribution of Al3Ti particles comparing with
the specimen deformed by route A. Based on these results, it was found that ECAPed Al-Ti alloy
specimen by route A has highly anisotropic microstructure. However, both ECAPed specimens with
routes A and Bc have no anisotropic wear property. That is because the wear property of the Al-Ti
alloy specimen depends on the shape of the Al3Ti particle. From these results, it was found that SPD
induced by ECAP is an effective processing method to make homogeneous wear property for the
metallic material containing platelet solid-particles.
How Fe60Co40 and Fe72Al28 Nano-Alloys Produced by Mechanical Alloying Behave when Exposed to Microwaves
Authors: Otmane Fadhela , Bergheul S. , Hamlati Z. , Azzaz M.
Published: March 2009

Fe60Co40 and Fe72Al28 nano-alloys were synthesized from elemental powders via highenergy
mechanical alloying. The prepared samples were characterized using X-ray diffraction,
scanning electron microscopy and X-band waveguide to measure the reflection loss in a frequency
range of 9-10 GHz. The XRD patterns show that disordered Fe60Co40 solid solution with a bodycentred
cubic structure is formed for milling times longer than 12 h, and after 4h milling, the solid
solution Fe72Al28 has been largely formed. Morphological studies indicate an average grain size of
10 to 15 nm. The microwave- absorbing characteristic reveal good performance for Fe60Co40
compared to Fe72Al28, the maximum reflection loss is about -12 dB for the absorber.
Structure and Functional Properties of Ti-Ni-Based Shape Memory Alloy after Electroplastic Deformation
Authors: Gurtovaya Irina , Prokoshkin Sergey , Inaekyan K.E. , Korotitskiy Andrey , Stolyarov Vladimir V. , Glezer Alex M. , Makushev S. , Khmelevskaya I. , Ugurchiev U. , Manaenkov S.
Published: March 2009

Application of electroplastic deformation (EPD) by rolling to bulk long-sized samples of
Ti-50.7 at.%Ni alloy allows increasing of the deformation strain without macrofailure by 1.5 to 3
times in comparison to cold rolling without electrical current application. Structure formation and
functional properties were studied after various EPD regimes: current density (84 to 168 А/mm2)
and impulse duration (80 and 160 ms). When the stage of mixed nanocrystalline and amorphous
structure formation is reached as a result of EPD, a post-deformation annealing at 400 °С leads to a
nanocrystalline structure formation in austenite and highest recovery stress values generation by the
martensite.
Influence of the Crystallization Kinetics on the Microstructural Properties of γ-PVDF
Authors: Silva M.P. , Sencadas Vitor , Rolo A.G. , Botelho Gabriela , Machado Ana Vera , Rocha José Gerardo , Lanceros-Méndez Senentxu
Published: March 2009

The kinetics of the isothermal crystallization of the γ-phase Poly(vinylidene fluoride) has
been investigated. Samples were prepared from the melt at different crystallisation temperatures and
the variation of the microstructure of the samples was monitored with time by optical microscopy.
Raman and Infrared transmission spectroscopies also show the appearance of the γ-phase for higher
crystallisation temperatures. Two types of γ-phase spherulites have been identified. These
spherulites represents different ways to obtain the γ-phase and show different thermal stability. The
correlation between microstructure and kinetic parameters allows the tailoring of the microstructure
by choosing the crystallisation conditions of the samples.
Ageing Effect on Aerial Lime Mortars Rheology
Authors: Seabra M.P. , Labrincha Joao A. , Ferreira Victor M.
Published: March 2009

One of the key characteristics of fresh mortars is their rheological behaviour since it
determines the material workability and has a clear influence on the hardened product final
properties. Indeed, mortars rheological properties are extremely important since several factors,
related with placement, consolidation, durability and strength depend on the flow properties of the
mortar paste. In this work, the effect of ageing time on the rheological properties of fresh aerial
lime-based mortars was investigated. Mortars having a 1/3 binder/aggregate volume ratio were
studied as a function of ageing time. The influence of a water retaining agent (0.1 wt. %) addition in
these mortars was also analysed. Mixing and ageing have a clear influence in the water intake
process ruling over the rheological behaviour of this type of mortars.
Bond-Slip Mechanisms of Hooked-End Steel Fibers in Self-Compacting Concrete
Authors: Cunha Vítor M.C.F. , Barros Joaquim , Sena-Cruz José
Published: March 2009

The experimental results of hooked-end steel fibers pullout tests on a self-compacting
concrete medium are presented and discussed in this work. The influence of fiber embedment length
on the fiber pullout behavior is studied. The role of the end hook of the fiber on the overall pullout
behavior is also investigated by carrying out tests with fibers without its end hook, in order to
separate the contribution of the frictional bond component from those derived from the mechanisms
provided by the end hook of the fiber. Finally, the experimental bond-slip relationships are modeled
by an analytical model.