bluuebunny/crossref_metadata_2025 huggingface dataset:
Designing Cryogenic Vapour-Cooled Current Leads
Authors: Augusto Paulo A. , Castelo-Grande Teresa , Barbosa Domingos , Estévez Angel M.
Published: March 2009

Constructing a new device we had to design some vapour-cooled current leads. This
current leads are made of Low-Tc material connected with copper wires and some parts of High-Tc
material. Its design is calculated keeping in mind the heat transfer by diffusion to a vapour-cooled
stream that surrounds the conductive materials. The design and the calculations performed to
achieve it, and also the background theory of the heat diffusion applied in this part of the device
will be described.
Cross Interdiffusion Coefficients in Nickel- and Iron-Based Ternary Alloys
Authors: Murata Yoshinori , Sakurai Shingo , Mabruri Efendi , Koyama Toshiyuki , Morinaga Masahiko
Published: March 2009

It is known that two main interdiffusion coefficients, ık
Dii and ık
Djj , as well as two cross
interdiffusion coefficients, ık
Dij and ık
Dji , are necessary for understanding the atomic diffusion for
ternary system. Here, k is the host element of ternary system, and i and j are solute
elements. These four interdiffusion coefficients are obtained from a series of experiments using
two kinds of ternary diffusion couples. In general, it is believed that ık
Dij and ık
Dji indicate the
same sign to each other, but there are a lot of experimental data showing that ık
Dij and ık
Dji
indicate opposite sign [1]. In such a case, the physical meaning of the cross interdiffusion
coefficient has not always been understood thoroughly. The purposes of this study are to measure
the interdiffusion coefficients by a series of experiments and to elucidate the physical meaning of
the two cross interdiffusion coefficients on the basis of the consideration about the relationship
between the thermodynamic functions and the cross interdiffusion coefficients. It is concluded
that ık
Dij exhibits the opposite sign to ık
Dji without contradicting the Onsarger’s reciprocity
theorem when the ( 2 2 )
c j ∂ G ∂c shows the opposite sign to ( 2 2 )
c i ∂ G ∂c . Here, c G is Gibbs free
energy of the ternary system.
Diffusion Kinetics Analysis of Cation Diffusion in YSZ and LSGM
Authors: Belova Irina V. , Murch Graeme E. , Samuelis D. , Martin Manfred
Published: March 2009

In this paper, we discuss different possible cation diffusion mechanisms in YSZ and
LSGM. Monte Carlo simulations are also reported of tracer diffusivities in LSGM for a
postulated cluster mechanism. These simulations extend earlier simulations on un-doped material.
The limits of the ratio of the diffusivities are consistent with experimental tracer diffusion
findings over a wide range of cation-vacancy exchange frequencies. We also develop
relationships between the phenomenological coefficients and use these relationships to predict
possible demixing and interdiffusion experimental outcomes.
Finite Element Modelling of Oxygen Diffusion and Segregation at Interfaces in Ag-MgO Composites: Parametric Studies
Authors: Öchsner Andreas , Belova Irina V. , Murch Graeme E.
Published: March 2009

The presence of atomic oxygen at internal metal-ceramic oxide interfaces signifi-
cantly affects the physical properties of the interfaces which in turn affects the bulk properties
of the material. This problem is addressed for the model system Ag-MgO from a phenomenolog-
ical point of view using the finite element method. The performed parametric studies investigate
the influence of different kinetic parameters of the diffusion-segregation system.
Kinetic Description of the Mass Transfer in Ladle Metallurgy Operations
Authors: Hernández Victor H. , Reyes Fidel , Gutiérrez Juliana , Plascencia Gabriel , Martínez Fernando
Published: March 2009

In this work a kinetic model which describes the main refining reactions in a ladle
furnace is depicted. The main difference between this work and other models previously reported
relies on a formal quantification of the multi-component diffusion kinetics expressed as an
analytical solution. Results from this model reproduce/predict adequately the chemical steps
involved in an integrated steel shop.
Effect of Doping, Composite Geometry and Diffusion Annealing Schedules on the Structure of Nb3Sn Layers in Nb/Cu-Sn Wires
Authors: Popova E.N. , Popov Vladimir V. , Romanov E.P. , Sudareva S.V. , Dergunova E.A. , Vorobyova A.E. , Balaev S.M. , Shikov A.K.
Published: March 2009

Kinetics of formation of superconducting Nb3Sn layers and the structure of bronzeprocessed
Nb/Cu-Sn composites with Zr, Zn or Mg-doped matrixes or Ti-doped Nb filaments of
different geometry have been studied by the methods of TEM, SEM and electron-probe
microanalysis. All the doping elements have been found to accelerate the rate of growth of the
diffusion Nb3Sn layers and consequently their thickness. Correlation between the diffusion
annealing schedules, the geometry of Nb filaments, the structure of the diffusion Nb3Sn layers and
the current-carrying characteristics of multifilamentary Nb/Cu-Sn composites has been established.
Atomic-Ordering Kinetics and Diffusivities in Ni–Fe Permalloy
Authors: Radchenko Taras M. , Tatarenko Valentin A.
Published: March 2009

Using the static concentration waves’ method and self-consistent-field approximation, the
Onsager-type kinetics equation is solved to describe the L12-type long-range order (LRO) relaxation.
To calculate the diffusivities for Permalloy, the experimental diffraction data in respect to
LRO-parameter evolution for Ni3Fe are used. Theoretical curves of a time-dependent LRO for Ni–
Fe are plotted. Dilution of alloying element (with a deviation from stoichiometry) results in deceleration
of the LRO-parameter history (at the initial evolution stage) and in an increase of its relaxation
time. Both statistical-thermodynamics and kinetics results show: at high temperatures, equilibrium
LRO parameter for non-stoichiometric Permalloys can be higher than for stoichiometric one.
Effect of Antioxidants and Atmosphere on the Phase Formation and Microstructure of In Situ MgO-Al2O3 Spinels
Authors: Naghizadeh Rahim , Rezaie Hamid Reza , Golestani Fard F.
Published: March 2009

The formation of in-situ spinel in Al2O3-MgO-C refractories along with different
antioxidants occurs at different atmospheres in surface and inner of refractories. Then the types and
microstructures of established phases have become increasingly important in these refractories. In
the present work, reactions on firing Al2O3-MgO samples with added graphite, Al, Si and SiC in air
or coke bed atmosphere at 1300°C and 1600°C have been studied. The results showed that with the
addition of graphite and Al especially at 1600°C in coke bed, high alumina-rich spinel
(Mg0.866Al1.83O3.611) was increased and in the microstructure were appeared high amount porosity.
In silicon and silicon carbide additive samples after firing at 1600°C in coke bed, sapphirine phase
were revealed.
Effect of Colloidal Silica and Nano Boehmite Mixture on Reaction Sintering, Microstructure and Physical Properties of Tialite
Authors: Naderi Golsa , Rezaie Hamid Reza , Shokuhfar Ali , Naghizadeh Rahim
Published: March 2009

Aluminum titanate (Al2TiO5) is an engineering ceramic with low thermal expansion
coefficient, excellent thermal shock resistance, good refractoriness and non-wetting with most
metals. In this work the use of colloidal silica and nano boehmite mixture in proper stoichiometry of
mullite in aluminum-titanate (tialite) has been studied. Analytical structural evaluations including
XRD, TEM and SEM have been used to characterize the influence of these additives on phase
transformation, sintering process and microstructure. The results show that the presence of nano
size silica and boehmite enhanced the densification leads to fine microstructure, mullite phase
formation and improve the tialite ceramics properties.
Nonclassical Properties of Molecular Diffusion in Liquids and Dense Gases
Authors: Rudyak Valery , Belkin A.A.
Published: March 2009

The diffusion of molecules in liquids and dense gases is demonstrated to be nonclassical
for long time intervals. This means that the time dependence of the mean-square displacement of
molecules is nonlinear. This result was obtained by molecular dynamics simulations over a wide
range of density of the medium. The problem of plateau values of the diffusion coefficient is
discussed. Nonclassical diffusion equations are derived and discussed.
Simplification of Ensemble Averaged Two-Phase Flow with Heat and Mass Transfer Equations for Boiling in a Channel
Authors: Aybar Hikmet Ş. , Sharifpur Mohsen
Published: March 2009

Generation of vapor and predication of its behavior is an important problem in many
industries. In this study, the three dimensional governing equations for turbulence two-phase flow
are derived using ensemble averaging two fluid model. The governing equations are simplified by a
heuristic approach based on boiling data, and the equations are used to obtain the parameters for
each phase along the channel. A computer program is written for the simplified one-dimensional
equations, and the results are compared with experimental data.
MnO-C Interaction – Thermodynamic Modelling of Phase Equilibria
Authors: Shubin A.B. , Shunyaev K. Y.
Published: March 2009

The interaction between manganese(II) oxide and carbon in powder mixtures may give
manganese carbides, condensed(c) and gaseous(g) manganese at different temperatures and
pressures. The initial assumptions and results of thermodynamic modelling of this interaction in
the temperature range 1600-2100 K at the pressures 0.1-1.0 MPa are presented in this paper.
Ternary Interdiffusion in L12-Ni3Al with Ir Alloying Addition
Authors: Ode Machiko , Garimella N. , Ikeda Muneaki , Murakami Hideyuki , Sohn Yong Ho
Published: March 2009

Average ternary interdiffusion coefficients in Ni3Al with Ir additions have been
determined using solid-to-solid diffusion couples annealed at 1200°C for 5 hours. Disc shaped
alloy specimens were prepared by the vacuum arc melting at compositions of Ni-24Al, Ni-25Al,
Ni-26Al, Ni-23.5Al-1Ir, Ni-24.5Al-1Ir, Ni-23Al-2Ir, Ni-23Al-2Ir, Ni-24Al-2Ir, Ni-23Al-3Ir
(at.%). Surfaces of alloys were polished down to 1200 grit and diffusion couples were assembled
in Si3N4 jig for initial bonding heat treatment at 1200°C for 0.5 hours. Additional diffusion anneal
was carried out at 1200°C for 4.5 hours outside of Si3N4 jig so that diffusion couples can be water
quenched. Concentration profiles of individual components were measured by electron probe
microanalysis using pure standard of Ni, Al and Ir. Interdiffusion flux of individual component
was determined directly from the experimental concentration profiles, and the moments of
interdiffusion flux were examined to calculate the average ternary interdiffusion coefficients, D˜ ij
k
either with Al or Ni as dependent component. Calculated interdiffusion coefficients suggest that
Ir-alloyed Al2O3-forming oxidation resistant coatings would be beneficial to reduce the
interdiffusion flux of Ni from superalloy substrates to the coating, and reduce the interdiffusion
flux of Al from the coating to the superalloy substrate.
Evaluation of the Coverage Pattern on the Fracture Surface of Bi-Embrittled Cu Grain Boundaries by Means of Auger Electron Spectroscopy
Authors: Yeh C.H. , Chang L.S. , Straumal Boris B.
Published: March 2009

In studying grain boundary segregation in Cu–Bi alloys by means of Auger electron
spectroscopy samples must be broken in-situ. Consequently, the distribution of segregants on both sides of
fracture path must be considered quantitatively. This question can be addressed by studying the influence
of an adsorbed oxygen layer on the intensity of Auger peaks. This oxygen layer forms on the fracture
surface when it is intentionally exposed to air. In this work, the values of Bi coverage have been measured
both on the as-fractured Cu fracture surface and on the fracture exposed to air. The coverage values
evaluated from the model of a crosstie-like pattern agree better with each other than those from the model
of a continuous layer. Our study reveals that the Cu-Bi bond is weaker than the Bi-Bi bond.
The Influence of Quenching Baths on Grain Boundary Wetting Transition in Sn–25 at% In alloy
Authors: Yeh C.H. , Chang L.S. , Straumal Boris B.
Published: March 2009

The wetting behavior of grain boundaries is affected by temperature, pressure and
misorientation of grain boundaries. However, the influence of quenching baths on liquid state grain
boundary wetting is rarely reported. In this work, this effect in the Sn−25 at% In alloy was
investigated. The Sn−In alloy was prepared by smelting of In and Sn at 300°C for 6 hr in Ar
atmosphere. Samples were annealed at temperature between 130 and 165°C and quenched in two
kinds of baths: −10°C salt-saturated water and liquid nitrogen. The results from X-ray diffraction
show a difference in preferential orientations between samples quenched in these two baths.
Metallographic analysis reveals that the percentage of grain boundaries fully wetted in samples
quenched in −10°C salt-saturated water is lower than that quenched in liquid nitrogen. It is pointed
out that a proper quenching bath is necessary for preserving the initial microstructure of grain
boundary wetting.
Thermal-Mechanical Responses of Ti-6Al-4V during Orthogonal Cutting Process
Authors: Tamin Mohd Nasir , Izman Sudin , Mon Thet Thet
Published: March 2009

Orthogonal metal cutting process involves large plastic deformation accompanied by
excessive heat generation. This work addresses the thermal-mechanical responses of the workpiece
material at the tool-workpiece contact. In this respect, the orthogonal cutting process of Ti-6Al-4V
using CVD diamond tool is simulated using finite element method. The cutting condition consists
of cutting speed, V=180 m/min, feed rate, t=0.125 mm/rev and width of cut of 1.25 mm. Eulerian
formulation with coupled thermal-mechanical analysis is employed in the model. The Johnson-
Cook constitutive equation is employed for Ti-6Al-4V workpiece material to accurately simulate
the formation of shear bands. The stick-slip friction condition is modeled at the tool-chip interface.
The sliding coefficient of friction of 0.8 and the limiting shear stress of 700 MPa for stick-slip
condition are determined experimentally. Results show that high temperature and temperature
gradient concentrate in the primary shear zone and the contact area between the tool rake face and
the chip. A primary shear band is predicted in the workpiece ahead of the tool-workpiece contact
face while the secondary shear band is formed in the chip. This highly-deformed shear band is
revealed in the microstructure of etched chips. The predicted high strain rate results in build-up
edge at tool cutting edge-chip contact. Low cutting condition of V=150 m/min, t=0.125 mm/rev
promotes stagnant zone formation that helps preserve the cutting edge of the tool. The maximum
predicted temperature at the cutting edge is in excess of 700 °C. Such high temperature level
facilitates diffusion of carbon elements into the chips and conversely, elements of titanium into the
CVD diamond tool.
Computational Study of Heat Transfer in Honeycomb Structures Accounting for Gaseous Pore Filler
Authors: Vesenjak Matej , Žunič Zoran , Ren Zoran , Öchsner Andreas
Published: March 2009

Thermal properties of honeycomb structures with different cell shapes are investigated in
this paper. The influence of cell shape, relative density and pore gases on the macroscopic
honeycomb thermal properties is investigated by means of transient dynamic computational
simulations. The ANSYS CFX code is used to evaluate the heat conduction trough the base material
and the filler gas, as well as the convection in gas filler. The computational results clearly show a
strong influence of the filler gas on heat conduction and macroscopic thermal properties of analyzed
honeycomb structures, which is attributed to low relative density of the cellular structure.
Additionally, the influence of considered relative densities is more prominent than the influence of
cell shape. The evaluated results are valuable for further development of homogenization models of
heat transfer in honeycomb structures accounting for gaseous pore fillers.
The Influence of Deep Cryogenic Treatment after Supersaturation of Al 4.7% Cu Alloy on Transformation during Ageing. Studies of Dilatometry, DSC, Hardness and XRD
Authors: Wierszyłłowski Ignacy , Wieczorek Sebastian , Andrzejewska Ewa , Marcinkowska Agnieszka
Published: March 2009

Studies of dilatometry, DSC, hardness and XRD have shown that a low temperature
cryogenic treatment immediately after supersaturation affects changes of structure and properties
taking place during ageing after supersaturation. The third peak visible on DSC diagrams for
samples conventially treated disappears on DSC diagrams for deep cryogenically treated samples,
and the intensity of the two first peaks on DSC diagrams of deep cryogenically treated samples is a
few times lower than on diagrams for conventionally treated samples. The dissolution process for
precipitation of Al2Cu in conventionally treated samples progresses faster. Hardness of samples
aged after a deep cryogenic treatment within the range of 175-220 oC for more than 60 minutes was
higher than of those conventionally treated; at higher ageing temperatures (275-350 °C) the
differences in hardness were smaller.
The Influence of Deep Cryogenic Treatment on Transformation during Tempering of Quenched D2 Steel. Studies oF XRD, Structures, DSC, Dilatometry, Hardness and Impact Energy
Authors: Wierszyłłowski Ignacy , Samolczyk Jarosław , Wieczorek Sebastian , Andrzejewska Ewa , Marcinkowska Agnieszka
Published: March 2009

The study analyses of influence of cryogenic treatment on the resultant structures, the development of
changes during tempering and the charcteristic obtained. It was observed that cryo treatment affects the changes
through: a significant reduction in retained austenite content, gradual reduction in value of martensite
tetragonality and an increase in the number of carbon atoms in transformations during tempering. The
consequence of the transformations taking place during cryogenic treatment is precipitation of η – carbide during
low tempering instead of ε – carbide. The number of η – carbides precipitated is higher than that of ε – carbide.
This affects the functional properties of steel products. Key words: cryogenic processing, supersaturation,
dilatometry, DSC, ageing.
Coupled FEM-BEM Approach for Axisymetrical Heat Transfer Problems
Authors: Mishuris Gennady , Wróbel Michał
Published: March 2009

This work deals with a stationary axisymmetrical heat transfer problem in a combined
domain. This domain consists of half-space joined with a bounded cylinder. An important feature of
the problem is the possible flux singularity along the edge points of the transmission surface.
Domain decomposition is used to separate the subdomains. The solution for an auxiliary mixed
boundary value problem in the half space is found analytically by means of Hankel integral
transform. This allows us to reduce the main problem in the infinite domain to another problem
defined in the bounded subdomain. In turn, the new problem contains a nonlocal boundary
conditions along the transmission surface. These conditions incorporate all basic information about
the infinite sub-domain (material properties, internal sources etc.). The problem is solved then by
means of the Finite Element Method. In fact it might be considered as a coupled FEM-BEM
approach. We use standard MATLAB PDE toolbox for the FEM analysis. As it is not possible for
this package to introduce directly a non-classical boundary condition, we construct an appropriate
iterative procedure and show the fast convergence of the main problem solution. The possible
solution singularity is taken into account and the corresponding intensity coefficient of the heat flux
is computed with a high accuracy. Numerical examples dealing with heat transfer between closed
reservoir (filled with some substance) and the infinite foundation are discussed.
The Clustering of Cu Atoms in Neutron Irradiated Reactor Pressure Vessel Steels Studied by Positron Annihilation
Authors: Čížek Jakub , Procházka Ivan , Kocik Jan
Published: March 2009

Defect studies of neutron-irradiated Cr-Mo-V (VVER-440) type reactor pressure vessel
steels were performed in the present work. The steels were irradiated in the nuclear power plant
reactor under the conditions of a regular operation. Characterization of the irradiation induced
defects was performed by two complementary techniques of positron annihilation spectroscopy: (i)
positron lifetime spectroscopy was used for identification of defects and determination of defect
densities, (ii) coincidence Doppler broadening was employed for investigation of Cu atom
aggregates. Long range diffusion of Cu atoms is assisted by the irradiation induced vacancies. The
solute Cu atoms form small clusters in the irradiated steels. Subsequent isochronal annealing of the
irradiated steel leads to vacancy assisted clustering of Cu atoms and formation of small precipitates.
The Cu clusters exhibit maximum diameter at 400oC. Above this temperature the clusters dissolve
again in the matrix.
Modeling of Flow and Transport Processes Occurred in a Typical Polymer Electrolyte Membrane Fuel Cell (PEMFC)
Authors: Vakouftsi E. , Marnellos G. , Athanasiou C. , Coutelieris Frank A.
Published: March 2009

In the present work, a three dimensional model examining the fluid flow along with the
fundamental transport phenomena occurring in a typical polymer electrolyte fuel cell (PEMFC), i.e.
heat transfer, mass transport and charge transfer, has been developed. The flow field was simulated
according to the well known Navier-Stokes equations, while the heat transfer was described by the
typical conduction/convection equation and the mass transport by the convection/diffusion one.
Furthermore, reaction kinetics were studied by the Butler-Volmer equation for the heterogeneous
reactions occurring at the porous electrodes. The developed model was numerically solved by using
the commercially available CFD package CFD-RC©, which is based on the multi-step finite volume
method. The fuel cell performance in terms of velocity, temperature, mass fractions of active
compounds and electric field has been investigated as well.
Diffusion during Powder Metallurgy Synthesis of Titanium Alloys
Authors: Ivasishin Orest M. , Eylon Daniel , Bondarchuk V.I. , Savvakin Dmytro G.
Published: March 2009

In the present study titanium alloys were synthesized by the blended elemental press-andsinter
powder metallurgy approach using hydrogenated titanium powder. Experimental
investigation and modeling of the homogenization processes during synthesis were used to analyze
peculiarities of mass transfer and factors affecting diffusion. Processes of alloying elements
redistribution during chemical homogenization of powder blends are shown to be strongly
dependent on the chemical composition of the initial powders. Optimization of the processing
parameters allows to synthesize uniform, nearly-dense material with reduced grain size, at relatively
low temperatures and short time. This will provide improvement of mechanical properties
simultaneously with better cost-effectiveness of the process.
Effect of Irradiation Doses on AlCu6.5 Alloy Using Positron Annihilation Doppler Broadening Technique
Authors: Abdel-Rahman M. , Lotfy Yahia A. , Abdel-Rahman M.A. , Badawi Emad A.
Published: March 2009

Positron Annihilation Spectroscopy (PAS) is a powerful and versatile tool for the
study of the microscopic structure of materials. Doppler Broadening Positron
Annihilation Technique (DBPAT) is the fastest technique used among positron
annihilation techniques. The dose effect in Al-6.5at. % Cu alloy was investigated by
means of DBPAT. An abrupt change in both the S and W line-shape parameter values
occurred at 70 kGy of irradiation. The S- and W-Parameters of the trapped positrons
at 70 kGy of γ−irradiation dose are about 48 % and 14 % respectively. The S- versus
W-parameter reveals a linear relationship indicating the presence of only one type of
defect. The S- and W-parameters have been used in the determination of the positron
trapping rate and the grain size of the AlCu6.5 alloy.
Dependence of Mono-Vacancy Formation Energy on the Parameter of Ashcroft's Potential
Authors: Ghorai Amitava
Published: March 2009

We show the calculation of the monovacancy formation energy ( v
FH E1 ) for three
different group-I monovalent fcc metals (Cu, Ag and Au) and two group-IV
tetravalent fcc metals (Pb and Th) use a pseudopotential approach. Ashcroft's empty
core model potential (AECMP) and nine different exchange and correlation functions
(ECF) are used. The variation of v
FH E1 with the parameter c r of AECMP for different
ECF shows variations with the metals, and c r is observed to be greater than Bohr
radius.
X-Ray Characterization of Ag Impurities in Na1-xAgxCl
Authors: Saravanan Ramachandran , Syed Ali K.S. , Prema Rani M. , Saravanan R.
Published: March 2009

The alkali halide Na1-xAgxCl, with two different compositions (x = 0.03 and 0.10),
was studied with regard to the Ag impurities in terms of the bonding and electron
density distribution. X-ray single crystal data sets have been used for the purpose.
The present analysis focused on the electron density distribution and hence the
interaction between the atoms is clearly revealed by maximum entropy method
(MEM) and multipole analyses. The bonding in these systems has been studied using
two-dimensional MEM electron density maps on the (100) and (110) planes and onedimensional
electron density profiles along the [100], [110] and [111] directions. The
mid-bond electron densities between atoms in these systems are found to be 0.175
e/Å3 and 0.183 e/Å3, respectively, for Na0.97Ag0.03Cl and Na0.90Ag0.10Cl. Multipole
analysis of the structure has been performed for these two systems, with respect to the
expansion/contraction of the ion involved.
Diffusion in the Lattice and Interfaces of Real Engineering Materials: A Unified Approach
Authors: Gupta Devendra
Published: March 2009

Engineering materials are commonly polycrystalline in nature and chemically
inhomogeneous containing hetero-phases and interfaces. Because diffusion is ubiquitous in
dissimilar phases and defects, it plays a vital role in the performance and reliability. During the last
several decades, a synergism of the microstructural properties and chemical inhomogeniety with
diffusion has been attempted to unify their apparently diverse behavior. We discuss the
methodology and the thermodynamical analyses of the diffusion data needed to obtain this
synergism quantitatively and illustrate it by the results obtained in a wide variety of materials, both
metallic and non-metallic. Investigations carried out in pure polycrystalline metals have yielded
grain boundary energies comparable to those directly measured. Furthermore, we discuss the role of
solute segregation at grain boundaries and interfaces in alloys in altering diffusion. From the
perturbations caused, the solute segregation parameters - the enthalpy and the entropy of binding -
have been extracted and levels of solute concentrations estimated. Finally, it is shown that similar
analyses when applied to complex materials, e.g. the Pb-Sn eutectic alloy, the Ni3Al intermetallic
compound, and an Ag-ceramic system, also result in acceptable values of interface energies and
segregation factors.
Kinetics and Mechanism of Growth of β-Solid Solution during Reaction Diffusion in Binary Titanium and Zirconium Alloy Systems
Authors: Tiwari G.P. , Taguchi Osamu , Iijima Yoshiaki , Kale G.B.
Published: March 2009

High temperature beta-phase in titanium and zirconium alloy systems decomposes
through an eutectoid reaction into a Ti- and Zr-rich a-solid solution and an intermetallic compound.
The present paper reports the layer growth kinetics of the b-solid solution phase in elemental
diffusion couples of titanium and zirconium. The growth kinetics obeys a parabolic growth law.
However, the temperature dependence of the growth rate constant shows a bimodal behavior. The
Arrhenius plot of the growth rate constant, which is linear at the start, becomes curved at lower
temperature ranges. The deviation from the Arrhenius plot of the growth rate constant is related to
the curvature in the solvus line of the b-solid solution.
A theoretical model for the reaction diffusion responsible for the growth of b-solid solution is
presented. The growth rate of b-phase is described by the equation
2
2 . .
W
k D C
t
b
= = b D x ,
where k is a growth rate constant and Wb is the thickness of the b-phase formed over a period of
time t, Db is the interdiffusion coefficient for the b-phase, DC is concentration range of b-phase and
x is a parameter which is a function of the miscibility gaps in the phase diagram on the either side of
the b-phase. The above equation provides a satisfactory description of the various aspect of the
phenomenon of the growth of b-phase in Ti-and Zr-alloy systems.
Alpha to Omega Transition in Shock Compressed Zirconium: Crystallographic Aspects
Authors: Jyoti G. , Tewari R. , Joshi K.D. , Srivastava Dinesh , Dey G.K. , Gupta S.C. , Sikka S.K. , Banerjee S.
Published: March 2009

In the present study, specimens of Zr were subjected to shock compression of 11.6 GPa.
TEM examination of the recovered samples revealed that during shock compression the a phase
has transformed into the w phase. The orientation relationships (ORs) between the a and w phase
have been determined using both the stereographic projection method and the correspondence
matrix method. Our ORs have been found to belong to the Variant I OR given by Usikov and
Zilbershtein (UZ) for statically compressed Zr samples. Our ORs are the same as the one reported
by Song and Gray (SG) on dynamically compressed samples. In the present paper it has been
shown that the OR of SG is a subset of the OR of UZ and is not apart from it. The mechanism of
a®w transition with respect to occurrence of an intermediate b (bcc) structure, during the
transition has also been explored. We also show in this study that the amount of the transformed w
phase decreases with increasing oxygen content in the samples that were shock loaded to the same
peak pressure, as is revealed by both the TEM and XRD results.
Novel Method of Evaluation of Diffusion Coefficients in Ti-Zr System
Authors: Bhanumurthy K. , Laik A. , Kale G.B.
Published: March 2009

The incremental diffusion couples are used for evaluating interdiffusion couples in a
narrow composition range and these results are extrapolated to get an estimate of impurity diffusion
coefficients. In fact, several incremental couples are needed to get impurity diffusion coefficients at
different compositions. This process is generally tedious. The present method describes a relatively
simple method for evaluating the diffusion coefficients using “step diffusion couples”. A simple
experimental method is described to prepare a step diffusion couple. This method involves
preparation of diffusion couples in two stages. In the first stage, diffusion couple is made between
the two materials in a conventional way and annealed for extended period of time to have a large
diffusion zone typically of the order of 2-3 mm. In the second stage, the starting materials are
placed on the diffusion couple in a direction perpendicular to the diffusion zone and annealed at a
suitable temperature for diffusion to occur between the diffusion zone and the starting materials.
This method is applied to study the interdiffusion behavior in the b phase of the Ti-Zr system.
Boltzmann-Matano and Hall’s methods were used to determine the interdiffusion coefficients and
their composition dependence. Kirkendall shift is observed towards Ti side and the intrinsic
diffusion coefficients of Ti is approximately three times that of Zr. The width of the diffusion zone
is strongly dependent on the composition of the step diffusion couple. It is observed that the
interdiffusion coefficients evaluated at the terminal compositions matched well those published
values in the Ti-Zr system. This experimental technique offers an easy and elegant method to
determine the diffusion parameters without the tedious preparation of incremental diffusion couples.
A Probabilistic Approach to Analyze Austenite to Ferrite Transformation in Fe-Ni System
Authors: Mohapatra Goutam , Sahay Satyam S.
Published: March 2009

Dilatometer is often used for in situ measurement of phase transformation by monitoring
the length change during heating or cooling cycle. However, the inevitable temperature gradient
across the specimen length during inductive heating, introduces uncertainty in temperature
measurements and hence the associated phase transformation kinetics. Due to this uncertainty, it is
more meaningful to interpret the transformation kinetics from dilatometry in terms transformation
ranges instead of unique values of fraction transformed. In the present work, a probabilistic
approach has been used to predict the fraction transformed ranges, arising due to the temperature
gradient during dilatometry. The approach has been validated for Fe-5.93 at.% Ni undergoing
austenite to ferrite phase transformation at various constant cooling rates.
Gibbs Free Energy Difference in Bulk Metallic Glass Forming Alloys
Authors: Dhurandhar Heena , Lad Kirit N. , Pratap Arun , Dey G.K.
Published: March 2009

The Gibbs Free Energy Difference between the solid and liquid phases (DG) is related to
nucleation frequency and has played an important role in predicting the glass forming ability (GFA)
of multicomponent metallic alloys. This is due to the fact that the maximum energy for nucleus
formation i.e. the activation barrier for nucleation has an inverse square relation with DG.
The Gibbs Free Energy Difference of three multi-component bulk metallic glasses namely
Mg65Cu25Y10, Zr57Cu15.4Ni12.6Al10Nb5 and Zr52.5Cu17.9Ni14.6Al10Ti5 have been evaluated using two
new expressions. The results show that the DG values calculated assuming DCp to be constant lie
closer to the experimental values for the Mg based system while in the case of two Zr based
systems, DG computed using the hyperbolic variation of DCp show improved agreement with the
experimental data.
Investigations of the EPR Parameters and Local Structure for one Cu2+ Center in CdS
Authors: Wei Li Hua , Wu Shao Yi , Hu Yue Xia , Wang Xue Feng
Published: March 2009

The EPR g factors g// and g and the hyperfine structure constants for one substitutional Cu2+ center in CdS are theoretically investigated from the perturbation formulas of these parameters for a 3d9 ion under trigonally distorted tetrahedra. In view of the significant covalency of the [CuS4]6 cluster, the ligand contributions are taken into account on the basis of the cluster approach. According to the calculations, the impurity Cu2+ is found not to occupy exactly the ideal Cd2+ site but to suffer a small inward displacement 0.12 Å toward the ligand triangle along C3 axis. The theoretical results by considering the above impurity displacement show reasonable agreement with the experimental data. The defect structure of this Cu2+ center is also discussed.
Slow Positron Annihilation in Ion-Implanted Silicon
Authors: Singh Girjesh , Shrivastava S.B. , Rathore M.H.
Published: March 2009

The mechanism of slow positron annihilation in ion-implanted Si has been discussed in terms of the Diffusion-Trapping model (DTM). The trapping of positron has been considered in native vacancies (monovacancies) and ion induced vacancies i.e. vacancy clusters. The model has been used to calculate the Doppler broadening line shape parameter (S-parameter) as a function of incident positron energy for different ion-implanted Si. It has been found that at lower energies the monovacancies and vacancy clusters both contribute to the S-parameter while, with the increase in positron energy the vacancy clusters are reduced. The S-parameter is found to be dependent on the fluency of the implanted ions.
Mechanical Testing of Diffusion Bonded Metallic Hollow Sphere Structure (MHSS)
Authors: Veyhl Christoph , Winkler Rolf , Merkel Markus , Öchsner Andreas
Published: March 2009

The paper investigates the mechanical properties of sintered hollow sphere struc-
tures. First of all, the Young's modulus, plastic modulus, initial flow stress, initial flow strain, plateau stress and densifcation strain are derived from compressive tests. In addition, the material behaviour during the compressive testing is described. Furthermore, the influence of different specimen shapes on the results is discussed.
Structural and Electron-Hopping Studies of Pr and Nd Substituted La2/3Ba1/3MnO3 Manganites
Authors: Huda Abdullah , Halim S.A.
Published: March 2009

The significance of substituting concentrations of Pr and Nd at La-sites, in La0.67Ba0.33MnO3 perovskite compounds, for the structural and electrical properties have been studied. Polycrystalline samples (La1-x Prx)0.67Ba0.33MnO3 and (La1-x Ndx)0.67Ba0.33MnO3 with x = 0.00, 0.167, 0.333, 0.5, 0.667, 0.833 and 1.0 were synthesized via conventional solid-state reaction in the bulk. All of the samples were calcined at 900oC for 12 hours, pelletized and sintered at 1300oC for 24 hours and investigated. In this paper the structural patterns and microstructural properties of bulk samples have been investigated via x-ray diffractometry (XRD) and scanning electron microscopy (SEM). XRD patterns show that these systems are single-phase, with orthorhombic distorted perovskite structures. The electrical property, Tp, was determined by using standard four-point probe resistivity measurements in the temperature range of 20 K to 300 K. The result shows that Pr and Nd dopants shift the value of TP to a lower temperature. When the temperature is above Tp, T > Tp, the variation of the electrical resistance was found to follow the an Arhenius-type law, ρ = ρo exp (-Ea/KBT). It was used to calculate the activation energy of every sample. The resistivity curves show semiconducting behavior of all samples above their Tp.
On some Conceptual Considerations for the Finite Element Simulation of the Oxygen Out-Diffusion in Ag-MgO Composites
Authors: Öchsner Andreas
Published: March 2009

The presence of atomic oxygen at internal metal-ceramic oxide interfaces signi¯-
cantly affects the physical properties of the interfaces which in turn affects the bulk properties
of the material. The application of numerical tools such as the ¯nite element method requires
some conceptional considerations if results from different finite element meshes of methods
should be comparable. This paper summarises some of these thoughts in order to provide the
right basis for comparative investigations.
Investigation and Comparison between Wear Properties of Powder Metallurgy (P/M) and Powder Forge (P/F) Product
Authors: Abdi Sadjad , Khorsand H.
Published: March 2009

In recent years powder metallurgy method P/M because of complicated parts production ability is used widely, but existence of porosities in this products will decrease mechanical properties in this method, but advanced powder metallurgy methods like powder forging P/F with having profits of powder metallurgy P/M because of visible reduce in porosities will decrease powder metallurgy problems. One of the mechanical properties that is effected by the porosity is wear properties ,in this research by comparison between two groups of specimen, that first group made by powder metallurgy method that had 14% amount of porosities and second group that made by powder forge method P/F that had less than 1% amount of properties and change in wear parameters in both of groups we survey wear properties and we compare wear rate and mechanism result is showing visible relation between wear properties and amount and morphology of porosities.
Defects and Diffusion in a Prototype of Shape Memory Alloys: β2' Au-Cd Alloys
Authors: Gupta Devendra , Lieberman David S.
Published: March 2009

The Au-Cd alloys continue to be important vehicles of research for the shape memory effect involving martensitic transformations and related phenomena.They transform to a variety of martensitic structures depending on the alloy composition and thermal history. Additionally, the Au-rich alloys display rubber like behavior involving thermo-elastic memory. Defects and diffusion play important roles in determining these properties. Defects and diffusion mechanisms in the Au- 47.5 - 50.5 at.% Cd alloys are examined. Diffusion in the nanometer regime and the states of defects are found to be important contributing factors to determine the shape memory effect, the variable martensitic transformations and the rubber like behavior, which are discussed in details.
Silver Self-Diffusion in Al2O3/QE22 Magnesium Alloy Matrix Composite
Authors: Stloukal Ivo , Čermák Jiří
Published: March 2009

Self-diffusion of 110mAg has been investigated in fiber reinforced QE22 magnesium alloy matrix composite. Short Saffil fibers (97% -Al2O3 + 3% SiO2) were used as reinforcement. The diffusion measurements were carried out in the temperature interval 648 – 728 K by serial sectioning method. The volume diffusion coefficients Dv (alloy without reinforcement) and the effective diffusion coefficients Deff (alloy with reinforcement) were obtained by analysis of the penetration curves. The silver diffusion coefficient in the interface boundary matrix/Saffil Di was also estimated. The temperature dependence of volume diffusion coefficients Dv was compared with previous data measured using 65Zn in the same alloy and with literature data for Zn impurity diffusion in Mg single crystal. It was observed, that the temperature dependence of both Deff and Di was significantly non-linear in the measured temperature interval. This behavior supports previous observations with zinc diffusion in the same alloy.
High Temperature Oxidation of Liquid Cu-Ti Alloy at 1473K
Authors: Sazaki Yasushi , Tomita Hiroki , Hino Mitsutaka
Published: March 2009

The kinetics of oxidation of liquid Cu-0.5mass%Ti alloy at 1473K in CO2-CO gas mixture has been investigated by varying the oxygen potential. The pO2 is set to be enough to oxidize Ti in liquid Cu-Ti alloy but not for the oxidation of liquid Cu. Alloy samples were taken with a quartz tube during the experiments and Ti and O contents in the samples were analyzed by inductively coupled plasma method, and infrared absorption method. The phases of the formed titanium oxide layers were consisted of several different titanium oxides and were identified by using EBSD. The oxidation rate was evaluated based on the change of the Ti content in the Cu-Ti melts. The apparent overall oxidation rate is reasonably represented by the parabolic rate law. This oxidation behaviour was well explained based on the multi-layered oxidation theory.
Diffusion Process of 8Li for Radioactive Beam Production
Authors: Re Mauro , Celona L. , Chines F. , Cuttone G. , Garufi D. , Messina G. , Rifuggiato D. , Rizzo D.
Published: March 2009

By bombarding a target with stable ion beams it is possible to produce nuclear radioactive species. The EXCYT facility at the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), in Catania, is based on a K-800 superconducting cyclotron injecting high intensity beam (up to 500 W) in a Target Ion Source (TIS) assembly, and on a 15 MV Tandem for post-accelerating the Radioactive Ion Beams (RIB). Radioactive species are produced in a solid porous target where, by diffusion, they will reach the target surface. After effusion through the target container, radioactive atoms are ionized, extracted at low energy, and changed in charge (if needed). Two stages of isobaric mass separators will clean the resulting radioactive beam from contaminants, thus the RIB is injected into the Tandem for the post-acceleration. TIS is operating at high temperature (up to 2700 K) under vacuum (10-4 mbar). The production of 8Li radioactive beam was performed by injecting a 13C4+ primary beam of 45 MeV/u on a porous graphite target. In this work we present a study to optimize the target geometry in order to increase the production of the RIB. Our first RIB was 8Li which mean life time is 1.212 s. The generation density of 8Li inside the solid target is calculated by EPAX II code. A simple diffusion model which takes into account either the nuclei generation and their decay, was computer simulated to estimate the efficacious diffusion coefficient of 8Li in porous graphite which resulted to be in the range of 10-6 - 10-5 cm2/s. Since the porous nature of the target, many diffusion mechanisms are active, our assumption, supported by experimental evidence, is that at such high temperature multi-grain diffusion prevails. Diffusion length inside the target of 8Li, before its decay, resulted to be sensible smaller than the target size, therefore we modified its geometry enhancing the RIB production by a factor of 3-4.
Experimental Investigation of Conditions of Water Diffusion before Cooking within Production Line of Red Beans
Authors: Sharifpur Mohsen , Rostamirad Sholeh
Published: March 2009

A lot of food industries are producing legumes such as bean and chickpea. Soaking which is diffusion of water in them is usually one of the processes in the production line before cooking. In this study, it is experimentally investigated the water diffusion on red beans as a function of time and temperature, and then the influence of this diffusion on the cooking time and the final volume of cooked legumes in different temperatures. Thus, the energy management and final volume of the production could be optimized with respect to the cooking time, cooking temperature and the duration of water diffusion and temperature condition of soaking before the cooking process. Also in the present study, volumetric water diffusion is defined for legumes, that is a function of the diffused water, the initial volume (before soaking) and final volume of the productions (after cooking). The results confirm that the final volume of the product and the cooking time are a function of the conditions of the water diffusion before cooking.
Three-Dimensional Study of Unsteady Flow in Fractured Horizontal Wells
Authors: Mimouni N. , Chikh Salahs
Published: March 2009

Numerical predictions are carried out in order to investigate the fractured horizontal well behaviour. A control volume based approach is used to solve the transient 3D diffusivity equation adopting an irregular hybrid grid. Effect of several parameters such as reservoir characteristics, fracture properties and physical and geometrical parameters of the reservoir and the well that may affect the well productivity and production are discussed. Simulation results allow to predict the optimum number of induced fractures.
Diffusion and Transformation of Eutectic Carbides in High-Speed Steels during Heat Treatment
Authors: Chaus Alexander S. , Beznák Matej
Published: March 2009

The structure and phase composition of high-speed steels of different grades after casting, annealing, and subsequent final heat treatment (quenching and tempering) have been studied focusing on diffusion processes. In order to investigate kinetics of both the structure and phase transformations in eutectic carbides upon heat treatments, different techniques of optical microscopy, electron microscopy (both scanning and transmission ones), X-ray diffraction, and energy dispersive X-ray analysis have been used.
Diffusion and Structural Changes in High-Speed Steels Alloyed with Boron
Authors: Chaus Alexander S.
Published: March 2009

The structure and phase composition of high-speed steels of different grades additionally alloyed with boron after casting, annealing, and subsequent final heat treatment (quenching and tempering) have been studied focusing on diffusion processes. In order to investigate kinetics of both the structure and phase transformations in eutectic carbides upon heat treatments, different techniques of optical microscopy, electron microscopy (both scanning and transmission ones), X-ray diffraction, and energy dispersive X-ray analysis have been used.