bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress Evolution in Thin Films; Diffusion and Reactions
Authors: Welzel U. , Mittemeijer Eric Jan
Published: March 2009

After a brief discussion of possible mechanisms of stress generation in thin film
diffusion/reaction couples, two recent experimental examples are reviewed: (i) Thin film diffusion
couples (Pd-Cu, individual layer thicknesses: 50nm) prepared by DC-magnetron sputtering on
silicon substrates. The microstructural development, phase formation and the stress evolution during
diffusion annealing have been investigated employing Auger-electron spectroscopy in combination
with sputter depth profiling, transmission electron microscopy, in-situ wafer-curvature
measurements and ex-situ and, in particular, in-situ X-ray diffraction measurements. (ii) Tin layers
on copper substrates (layer thicknesses of some microns) prepared by electrodeposition. Upon
storage at ambient temperatures, Cu diffuses into the Sn layer and forms the intermetallic phase η’-
Cu6Sn5. The phase formation is accompanied by a volume expansion and as a consequence,
compressive residual stresses can be generated in the Sn layers. These compressive residual stresses
may drive the formation of Sn whiskers on the Sn surface. The microstructural development, phase
formation and the stress evolution during diffusion annealing have been investigated employing
scanning electron and focused ion beam microscopy, metallography and ex-situ and, in particular,
in-situ X-ray diffraction measurements.
The Temperature Dependence of the Atoms Co Diffusion Coefficient in Pt80Co20(111) Alloy
Authors: Vasylyev M. , Tinkov Vitaliy A. , Sidorenko Sergey I. , Voloshko S.M.
Published: March 2009

The method of Ionization Spectroscopy is used to study the thermo-induced kinetics of
surface segregation of the Pt80Co20(111) alloy components. The temperature dependence of the Co
diffusion coefficient in this alloy is determined. It is found that the value of the activation energy for
the segregation of Co atoms in the near-surface region is close to the heat of sublimation of pure
Co.
Diffusion in Metallic Melts
Authors: Griesche Axel , Macht M.P. , Frohberg Günter
Published: March 2009

We present diffusion measurements in metallic melts measured by capillary techniques and results of molecular dynamic simulations. The investigated systems are the binary alloy AlNi20 and the multicomponent bulk glass-forming alloy Pd43Cu27Ni10P20. The temperature range of interest reached from the glassy state to the equilibrium melt. In the glassy as well as in the deeply supercooled state, below the critical temperature Tc of the mode-coupling, theory (MCT), diffusion is a highly collective atomic hopping process. Both investigated systems show around Tc a change in the diffusion mechanism. Above the liquidus temperature, diffusion in Pd43Cu27Ni10P20 is a collective process whereas in AlNi20 the atoms diffuse probably by uncorrelated binary collisions. The influence of thermodynamic forces on diffusion in the liquid state of AlNi20 can be described by the Darken equation with an additional temperature independent correction factor (“Manning”- factor).
Growth Kinetics of Intermetallic Phases in U-Mo vs. Al Alloy Diffusion Couples Annealed at 550°C
Authors: Perez E. , Hotaling N. , Ewh Ashley , Keiser Dennis D. , Sohn Yong Ho
Published: March 2009

This study examined the growth kinetics of intermetallic phases that develop in solid-tosolid
diffusion couples assembled with U-7, 10 and 12wt.%Mo vs. Al alloys (Al, Al-2wt.%Si, Al-
5wt.%Si, 4043 and 6061) after a diffusion anneal at 550°C for 24 hours. Based on interdiffusion
microstructure and integrated interdiffusion coefficients, the addition of Si into the Al matrix alloy
was observed to significantly reduce the growth rate of the intermetallic layer that primarily
consisted of (U,Mo)Al4 phase. Growth rate of the (U,Mo)Al4 intermetallic layer also increases
slightly with Mo content; however, it was not significant compared to the effect of alloying Si into
Al alloys. Growth kinetics of (U,Mo)Al4 intermetallic layer appear highly sensitive to composition
of U-Mo fuel alloy and Al cladding alloys, and must be an important criteria in alloy
development/selection for optimum fuel performance with due consideration for compositiondependent
multicomponent interdiffusion.
The Influence of Solid State Diffusion on Microstructural Development during Solidification
Authors: DuPont J.N.
Published: March 2009

The primary factors that effect solid state diffusion during solidification are described and binary solute redistribution equations that permit estimation of the significance of solid state diffusion are discussed. Model calculations suggest that solid state diffusion of substitutional alloying elements in FCC alloys is insignificant under most processing conditions, while that of interstitial alloying elements is likely to be complete. Experimental data that supports these results are presented. Several cases that highlight the practical importance of microsegregation on performance of engineering alloys are described as well as methods for avoiding or minimizing microsegregation for improved properties. A solute redistribution model for handling the limiting cases of solute diffusion in ternary alloys is presented and model calculations are reviewed to reveal the strong influence diffusion can have on the solidification path and resultant microstructure.
Calculation of Gas Carburizing Kinetics from Carbon Concentration Profiles based on Direct Flux Integration
Authors: Karabelchtchikova Olga , Sisson Richard D.
Published: March 2009

Initiated by the need of industry for gas carburizing process control and optimization, this paper
focuses on understanding the effect of the time, temperature and carbon potential on the mass
transfer coefficient and carbon diffusivity in Austenite. A method for direct flux integration has
previously been proposed to calculate these kinetic parameters from the experimental carbon
concentration profiles. AISI 8620 steel discs were gas carburized at different levels of atmosphere
carburizing potential for selected austenizing temperatures. Analyses of the carburized parts
included experimental measurement of weight gain, surface carbon concentration and carbon
concentration profiles. The time-dependent weight gain and surface carbon content measurements
allowed calculation of the time average mass transfer coefficient, while carbon concentration
profiles were used to calculate the concentration dependent carbon diffusivity for selected process
parameters. Excellent agreement was found between the calculated mass transfer coefficient and
carbon diffusivity values and those reported in the literature. The calculated values served as input
in the previously developed carburizing model validating the predicted results by comparison with
the experimental concentration profiles.
Stability and Shrinkage by Diffusion in Hollow Nanotubes
Authors: Evteev Alexander V. , Levchenko Elena V. , Belova Irina V. , Murch Graeme E.
Published: March 2009

The shrinkage via the vacancy mechanism of a mono–atomic nanotube is described.
Using Gibbs–Thomson boundary conditions an exact solution is obtained of the kinetic equation in
quasi steady–state at the linear approximation. A collapse time as a function of the size of a
nanotube is determined. Kinetic Monte Carlo simulation is used to test the analytical analysis.
A Mathematical Formulation for Interfacial Diffusion, Incorporating Deviation from the Classical Random Walk Theory
Authors: Raghavan N.S. , King A.H.
Published: March 2009

Fisher’s model for grain boundary diffusion considers the lattice and the grain boundary on the same basis by presuming the validity of Fick’s second law for both cases, despite the significant structural differences between them. Recent studies [1-3] have, however, shown that grain boundary diffusion is profoundly different from lattice diffusion. We propose an alternative mathematical formulation that incorporates these structural differences and consequently models grain boundary diffusion phenomena more accurately than Fisher’s model. This is achieved by considering possible deviations from the classical random walk for solute atoms diffusing through grain boundaries. This formalism can also be applied to surface diffusion and triple junction diffusion.
Measurement of Oxide Barrier-Film Thickness of Al-Alloy by Electrochemical Impedance Spectroscopy at the Nanometre-Scale
Authors: Habib Khaled , Al-Muhanna K. , Al-Sabti F. , Al-Arbeed A.
Published: March 2009

In the present work, the electrochemical behavior and the oxide barrier-film thickness of
anodized aluminum-magnesium (Al-Mg) alloy were determined in the as-received and annealed
conditions by using electrochemical techniques. Electrochemical parameters such as the
polarization resistance, solution resistance, alternating-current (AC) impedance, and the doublelayer
capacitance of the anodized Al-Mg alloy were determined in boric acid solutions, with 0 to
10%H3BO3, by using electrochemical impedance spectroscopic (EIS) methods. The oxide barrierfilm
thickness of the anodized Al-Mg alloy was then deduced, from the electrochemical parameters
obtained, as a function of the boric acid concentration (0 to 10%H3BO3). The optimum thickness of
the oxide barrier-film was detected for as received samples (1.17nm) and for annealed samples
(1.22nm) at a boric acid concentration of 4%H3BO3.
Important Features of Anomalous Single-Dopant Diffusion and Simultaneous Diffusion of Multi-Dopants and Point Defects in Semiconductors
Authors: Dao Khac An
Published: March 2009

This paper summarizes some of the main results obtained concerning aspects of
anomalous single-dopant diffusion and the simultaneous diffusion of multi-diffusion species in
semiconductors. Some important explanations of theoretical/practical aspects have been
investigated, such as anomalous phenomena, general diffusivity expressions, general non-linear
diffusion equations, modified Arrhenius equations and lowered activation energy have been offered
in the case of the anomalous fast diffusion for single-dopant diffusion process. Indeed, a single
diffusion process is always a complex system involving many interacting factors; conventional
diffusion theory could not be applied to its investigation. The author has also investigated a system
of multi-diffusion species with mutual interactions between them. More concretely, irreversible
thermodynamics theory was used to investigate the simultaneous diffusion of dopants (As, B) and
point defects (V, I) in Si semiconductors. Some attempts at theory development were made, such as
setting up a system of general diffusion equations for the simultaneous diffusion of multi-diffusion
species involving mutual interactions between them, such as the pair association and disassociation
mechanisms which predominated during the simultaneous diffusion of dopants and point defects.
The paper then gives some primary results of the numerical solution of distributions of dopants (B,
As) and point defects (V, I) in Si semiconductor, using irreversible thermodynamics theory. Finally,
several applications of simultaneous diffusion to semiconductor technology devices are also
offered.
New Method to Determine Young’s Modulus of Micro Crystal Based on Raman Spectrometer
Authors: Sang Sheng Bo
Published: March 2009

With the development of MEMS, the mechanical properties of micro crystals must to be
determined to know the defect, reliability and characterization of MEMS. Young’s modulus is one
of the most important properties, which indicates the ability of resisting the elastic deformation.
Many methods, such as natural frequency measurement, beam bending tests, membrane bulge test
and uniaxial tension test, have been used to measure Young’s modulus of Si, SiN and metals. But
there are some limitations when they are used to measure micro crystals in MEMS. This paper puts
forward a high accuracy and convenient method----using Raman spectrum to measure Young’s
modulus of micro crystals in MEMS, and sets up the measurement system. Measured Young’s
modulus of Si and GaAs in [100] crystallographic orientation are 161.113GPa and 84.128GPa
respectively, which correspond with the Yong’s modulus in common use now. Based on the values,
it can be analyzed if there are some defects in the micro crystals.
First-Principles Investigation of the Alloying Effect of Mn and Cr in the Kink on the Edge Dislocation in BCC Iron
Authors: Qiu Zheng Chen , Chen Li Qun
Published: March 2009

Using the first-principles self-consistent discrete variational method based on density
functional theory, we investigated the energetics and the electronic structure of 3d impurity Mn and
Cr in the kink on the [100](010) edge dislocation in bcc iron. The calculations of binding energies
show that both Mn and Cr can stabilize the system containing kink. We also calculate the structural
energy, the interatomic energy, the local density of states and the charge density difference. The
results indicate that both Mn and Cr in the kink can enhance the interatomic interaction between the
impurity atom and the neighboring Fe atoms due to the hybridization of impurity d-Fe d orbitals. The
introduction of the Mn and Cr impurity leads to a strong pinning effect on the dislocation motion in
bcc iron, which may explain the solid solute hardening of Mn and Cr.
Growth Kinetics of Boride Layers: A Modified Approach
Authors: Campos-Silva Ivan , Ortíz-Domínguez M. , VillaVelázquez C. , Escobar R. , López N.
Published: March 2009

This study evaluates the boron diffusion in the Fe2B phase formed at the surface of AISI
1018 steels during the paste boriding process. The treatment was carried out at temperatures of
1123, 1173, 1223 and 1273 K with 2, 4, 5, 6 and 8 h exposure times for each temperature using a 4
mm layer thickness of boron carbide paste over the material surface. The boron diffusion coefficient
Fe2B D was determined by the mass balance equation and the boride incubation time assuming that
the boride layers obey the parabolic growth law, while the boron concentration profile along the
interphase Fe2B/substrate was unknown. The boron diffusion coefficient was interpreted as a
function of the treatment temperature, obtaining the activation energy value for diffusion controlled
growth of Fe2B boride phase.
Intrinsic Diffusivities and Modeling of the Diffusion Multiples
Authors: Danielewski Marek , Wierzba Bartłomiej
Published: March 2009

In order to model the diffusion in multicomponent and multiphase systems
we define and use the volume fixed frame of reference. In this unique frame all
diffusion fluxes are expressed by the combined Darken-Nernst-Planck formulae. The
components mobility is estimated using the NIST data and Calphad approach. The
resulting CADiff method is used for the modeling (inter)diffusion process in the
multicomponent diffusion multiple. We shows results for the IN718-Rene88 terminal
compositions. Comparison of the simulation results with experimental data shows
good agreement. The presented CADiff method allows to model interdiffusion in
multicomponent non-ideal systems. When the thermodynamical data are available,
the method allows to include reactions, variable partial molar volumes and effect of
stress.
Electro-Diffusion in Multicomponent Ion-Selective Membranes; Numerical Solution of the Coupled Nernst–Planck–Poisson Equations
Authors: Grysakowski Bartosz , Bożek Bogusław , Danielewski Marek
Published: March 2009

Numerical simulations of evolution of the potentials and impedance spectra of ionselective
membranes (ISEs) with ionic sites are presented. The Nernst–Planck–Poisson and
continuity equations (NPP) are solved numerically by means of the finite difference method, the
Rosenbrock solver and with the use of Matlab platform. Transient solutions for ion-selective
electrodes under open- and closed-circuit conditions are computed. The potential-time response to
small-current perturbation is used for determination of complex impedances. We present
simulations of ISEs as a function of varying diffusivities and ionic concentrations in the “bathing”
solutions at interfaces. It is shown that the non-Nernstian behavior of passive membrane electrodes
is a result of kinetic constraints at the interfaces, which is manifested in the appearance of an
additional arc between the high-frequency bulk and the low-frequency (Warburg) arcs. The
presented approach directly relates the diffusivities in the membrane and the interface properties
(heterogeneous rate constants determining the transport across interfaces) to the characteristic
features of impedance spectra (dimensions and characteristic radial frequencies). NPP problem
solved on the Matlab platform allows simulating of the non-linear effects in electro-diffusion.
Experimental Values of Diffusion Coefficients of Organic Compounds in Water
Authors: Delgado João M.P.Q.
Published: March 2009

Mass transfer around a slightly soluble cylinder, aligned with the direction of liquid flow
in a packed bed of sand particles, is analysed for transport by advection and molecular diffusion.
The theoretical analysis applies to cylinders that are large in comparison with the inert particles, so
that the bed may be treated as a continuum.
Experimental measurements of mass transfer in water were carried out at temperatures that differ
significantly from ambient value. The soluble cylinders used in the experiments were made of either
salicylic acid or cinnamic acid and the range of temperatures covered were 278 to 343 K, for the
dissolution of salicylic acid, and 278 to 328 K, for cinnamic acid in water. Using the mass transfer
theory presented in this work the molecular diffusion coefficient of the two solutes was determined,
and good agreement with literature values was found.
A Calorimetric Study on the Precipitation of T1 Phase during the Ageing of an Al-Li-Cu-Zr Alloy
Authors: Ahmadi Shahram , Shokuhfar Ali , Abotalebi M.R. , Rezaei Arash
Published: March 2009

The precipitation of T1 phase during the ageing of an Al- Li- Cu -Zr alloy sheet was
studied by DSC (Differential Scanning Calorimetric) technique. Results showed that
precipitation of T1 phase occurred in temperature range of 250°C to 300°C whereas its
dissolution occurred within the temperature of 450°C to 530°C. Furthermore, activation
energies for precipitation and dissolution of T1 phase were determined 122.1 kJ/mol and
130.3 kJ/mol, respectively.
Concentration Dependent Diffusion in Building Materials – Application of Different Methods
Authors: Ramos N.M.M. , Delgado João M.P.Q. , de Freitas V.P.
Published: March 2009

Moisture is an important factor when analyzing the behaviour of building elements and
materials. A deeper knowledge on moisture transport under transient conditions of environmental
air temperature and humidity is required. In this experimental work, the measurements of moisture
diffusion coefficients, w D , of three different types of building materials commonly used in Portugal
(gypsum plasterboard, gypsum plaster and gypsum+lime plaster) were obtained for different values
of temperature and relative humidity.
The results obtained were in good agreement with the values found in literature and show that
the increase in temperature resulted in an increase in the diffusion coefficient and an increase in
relative humidity (54% to 69%) resulted in a decrease in w D .
Anomalous Diffusion during Water Absorption in Porous Building Materials – Experimental Evidence
Authors: Ramos N.M.M. , Delgado João M.P.Q. , de Freitas V.P.
Published: March 2009

The sorption and transport of water in two porous building materials, clay brick and
autoclaved aerated concrete, was studied in detail. The evolution of the distribution of liquid in the
porous medium was analysed in terms of the Boltzmann transform method and anomalous diffusion
equation proposed by Küntz and Lavallée [1].
The apparent moisture diffusion coefficients of water were determined from the total water
profiles using a modified Boltzmann-Matano analysis, and a good agreement with literature values
was found. The application of anomalous diffusion model to building materials indicates that the
previous 1/ 2 t relation is not entirely accurate to estimate the volume of absorbed water. This result
has particular relevance for evaluating the durability of building structures.
Influence of Burner Geometry on Flame Characteristics of Propane-Air Mixture: Experimental and Numerical Studies
Authors: Pinho C.E.L. , Delgado João M.P.Q. , Ferreira V. , Pilão R. , Pinho C.
Published: March 2009

This work describes an experimental and numerical study to determine the corresponding
detailed thermal and fluid dynamic fields developed in a burner element for domestic water heaters.
A three-dimensional burner element was designed in real scale and numerical studies using
Fluent code were carried out in steady-state conditions to allow continuous observations and
measurements of the influence of burner element geometry and fuel-air velocity on flame
characteristics, namely colour, length and stability. Air has been used as a fluid. The computational
results, specifically the velocity and flame characteristics were verified with experimental data
obtained in order to ensure a stable flame. In order to evaluate the power generated and the
emissions of CO2 and CO associated to different burner element geometries, some experiments
were performed using single burner elements with a stainless steel prismatic tank covered with
thermal insulation to minimize heat losses.
Systematics of Grain Boundary Diffusion and Solute Segregation in Copper Poly- and Bicrystals
Authors: Divinski Sergiy V.
Published: March 2009

Recent results on radiotracer grain boundary diffusion of different solutes in the same
high-purity polycrystalline copper are reviewed. The measurements were performed in extended
temperature intervals satisfying Harrison’s B and C regime conditions at higher and lower
temperatures, respectively. In the B regime, the triple product P = sδDgb was determined, while the
grain boundary diffusivity Dgb was directly measured in the C regime (s is the segregation factor
and δ the grain boundary width). Consequently, the segregation of different solutes in the copper
matrix was determined for the true dilute limit conditions. The results on grain boundary diffusion
and segregation are analysed in relation to the solute – solvent binding and solute – vacancy
interaction in the bulk and in the grain boundaries. By increasing amount of the applied radiotracer
the effect of solute concentration on grain boundary diffusion can thoroughly be examined. Grain
boundary diffusion experiments on well-characterised bicrystals have been shown to be most
suitable for such a study. In a radiotracer experiment, the complete solute segregation isotherm can
be measured beginning already from a dilute solution in both, bulk and grain boundary.
Metal Oxides Interaction with Reducing Gas in Bubble Ore Melt
Authors: Dmitriev A.N. , Kudinov D.Z. , Leontiev L.I.
Published: March 2009

The mathematical model which allows us to describe, with the help of calculations of
thermodynamic balance, the kinetics of barbotage of oxide melt by various reducing gases is offered. The
algorithm of calculation is developed. The model is tested on system NiO-FeO-Al2O3-SiO2-CaO-Mg-COCO2.
The comparative analysis of computation and experimental data has shown that the offered model can
be used in the qualitative analysis of processes of interaction of multicomponent oxide melts with gasesreducers
of various composition. The calculations describing the kinetics of reduction of nickel oxide by
hydrogen in system NiO-CaO-B2O3 in an interval of temperatures 1473-1973 K are carried out.
Investigation of the Effects of GP Zones Formation on the Properties of AA2090 Alloy
Authors: Ahmadi Shahram , Shokuhfar Ali , Rezaei Arash
Published: March 2009

To respond the need of industries to the new materials with higher specific modulus and
lower density than those of the older Al alloys, aluminum- lithium alloys have been invented and
improved. Aging process is one of the most important methods to improve the mechanical properties
of aluminum- lithium alloys which are in the heat treatable category of aluminum alloys. Low
temperature and natural aging processes cause the "short range diffusion" of Cu atoms in the
aluminum and the formation of the GP zones. In this research, stability of GP zones and the effects of
these areas on physical and mechanical properties of AA2090 alloy were investigated by hardness,
electrical resistance, DSC (differential scanning calorimetric) and tensile tests. Results show that
endothermic effect in the DSC diagrams of AA2090 alloy at 180°C to 240°C can be related to the
enthalpy of GP zones dissolution. Formation of GP zones in the structure increases hardness, tensile
strength and electrical resistance of Al- Li C u (2090) alloys.
About Forecasting Durability of Particles of Iron Powders and Sintered Materials
Authors: Dmitriev A.N. , Bulanov V.I.
Published: March 2009

Equations for an estimation of hardness and durability of materials of particles of iron
powders in various zones are received. The opportunity of reception of materials with
physicomechanical properties above separate zones of particles is shown. By development of
technological processes of manufacturing sintered details with demanded physicomechanical
properties it is necessary to know the physical characteristics of particles of an initial material, and
sintered ensemble with them and their possible limiting values. However, definition of separate
mechanical characteristics of particles is impossible because of their small sizes and complex form.
Authors attempt to define strength and fluidity of various zones of particles of iron powders and
sintered materials on their basis, using a method of microhardness testing.
Optimization of Intermittent Hot Air Drying of Mango (Mangifera Indica L.)
Authors: Váquiro H.A. , Mulet A. , García-Pérez J.V. , Clemente G. , Bon J.
Published: March 2009

Intermittent drying is an alternative technology to continuous drying that improves the
product quality as result of diminishing the average material temperature and the heating time. In
this study, the application of the intermittent drying technology to mango drying (Mangifera indica
L.) was analyzed and optimized. To formulate the optimization problem, an objective function was
proposed in order to improve the product quality and decrease the energy consumption. To quantify
the objective function, a mathematical model for a cubic shape was formulated and validated,
considering diffusional mass and heat transfer with non-negligible external resistances.
Oxygen Diffusion in Superconducting Oxides
Authors: Grandini Carlos Roberto , de Albuquerque Gimenez Juliana Maria , da Silva Marcos Ribeiro , do Nascimento Rodney Marcelo
Published: March 2009

Since the discovery of high-temperature superconductivity of cuprate oxides, it has been
clear that it is strongly affected by the oxygen content, which is also a crucial factor to determine
other physical properties of high Tc superconductors. Non-stoichiometric (interstitial) oxygen
strongly influences the physical properties of various superconducting oxides, in particular by
creating conducting holes. It is now ascertained that the amount of holes injected depends not only
on the content of interstitial oxygen, but also on its ordering. Rearrangement of the oxygen ordering
may occur even below room temperature due to the unusual high mobility of these atoms. This
way, mechanical spectroscopy is one of the most adequate techniques for the study of the mobility
(diffusion) of oxygen atoms. This technique allows the determination of the jump frequency of an
atomic species precisely, regardless of the model or the different possible types of jumps. In order
to evaluate the mobility and the effect of oxygen content on these oxides, ceramic samples we
prepared and submitted to several oxygen removal cycles alternately with mechanical relaxation
measurements. As for SBCO, it was assumed that the peak was due to O(1)-O(5) jumps of oxygen
atoms at the chain terminals or in chain fragments in the orthorhombic phase. In the case of
BSCCO, the results showed complex anelastic relaxation structures, which were attributed to
interstitial oxygen atom jumps between two adjacent CuO planes.
Thermodynamical Behaviour of PdSe2 while Subjected Isothermally to High Pressure – Volumetric Level Analysis
Authors: Grigorova Veneta
Published: March 2009

We study thermodynamically the behaviour of PdSe2 while subjected to high pressure
under isothermal conditions. The present paper discusses the volumetric-level calculations and
results. Experiments under two certain temperature levels are performed: 20oC and 300oC.
Calculations and analyses are done according to the method for thermodynamical analysis
developed by us in [1]. We detected the order of phase transition from PdS2 structure type to pyrite
one to be first order notwithstanding the temperature level. Values of transition pressure were found
to be 12.24 GPa and 9.785 GPa at 20oC and 300oC, respectively. Adjusted entropy generation
during compression was calculated aiming to study stability of treated compound. Influence of
compression temperature level was analysed, as well as duration of pressure plateaux.
Diffusion Brazing of Single Crystalline Nickel Base Superalloys Using Boron Free Nickel Base Braze Alloys
Authors: Heinz Paul , Volek Andreas , Singer Robert F. , Dinkel Markus , Pyczak Florian , Göken Matthias , Ott Michael , Affeldt Ernst , Vossberg Andreas
Published: March 2009

Brazing is a well established repair technique for high temperature components in both
industrial gas turbines and aero engines. Conventional nickel base braze alloys contain boron or
silicon as melting point depressing elements. The major benefit of boron and silicon compared to
other melting point depressants is its large effect on the melting point and its high diffusion
coefficient in nickel base superalloys. However these elements promote precipitation of undesired
brittle phases during the brazing process. To avoid these phases, transient liquid phase bonding in
combination with boron and silicon free brazing alloys will be examined in this work. The influence
of the brazing temperature on solidification and diffusion behaviour during transient liquid phase
bonding for a single crystalline first generation and a second generation superalloy will be reported.
Our experiments show that isothermal solidification without precipitation of brittle phases in the
braze joint or the base material can be achieved. The brazed joint consists of fine γ/γ´
microstructure. EBSD measurements demonstrated that the single crystalline orientation of the base
material was maintained throughout the joint. Electron probe micro analysis is used to characterize
the diffusion behaviour. Solidification velocity will be compared with the theory of transient liquid
phase bonding established by Tuah-Poku [1].
Growth Kinetics of Fe Boride Layers: Application of a Diffusion Model
Authors: Keddam Mourad
Published: March 2009

In the present work, a kinetic study based on a diffusion model was performed by use of
both kinetics and thermodynamic data as input parameters, it was possible to evaluate the kinetic
constant at each phase interface for a biphase configuration FeB and Fe2B grown over the surfaces
of Armco Fe and Fe-Cr binary alloys at 0.5 and 4wt. %Cr by powder- pack boriding. The simulated
values of the kinetics constants by the model were compared to those found in the literature and a
good agreement was observed. For the Fe-4wt. %Cr alloy, it was found by simulation that the layer
thickness ratio between the FeB and Fe2B phases is very sensitive to the increase of temperature and
surface boron content.
Influence of the Transition to Nanoscaled State on Electrochemical Properties of LaMnO3+δ Oxide
Authors: Kozhina G.A. , Ermakov A.N. , Fetisov V.B. , Fetisov A.V. , Fishman Anatoly Yakovlevich , Petrova S.A. , Zakharov Robert Grigorievich , Shunyaev K. Y. , Rassokhin S.V.
Published: March 2009

The electrochemical behavior of perovskite type LaMnO3 (LMO) oxides with different
mean particle size was studied by voltammetry with the use of a carbon paste electroactive
electrode. Three stages of electrochemical reduction were recognized. The first two of them are
related to the release of oxygen from the crystal lattice in the range of two side nonstoichiometry of
LaMnO3±δ whereas the final stage is conditioned by the decomposition of LaMnO3-δ into new
phases. The nature of these phases and their formation mechanisms are different for nano- and
microparticles. The utmost size effect appears on cathodic curves recorded from the stationary
potential. The effect is not only due to the size factor but also due to the difference in
electrochemical properties of nano- and microparticles. While the decomposition of LaMnO3
microparticles proceeds into La2O3 and MnO oxides, the nanoparticles decompose through the
intermediate stage of Mn3O4 formation in accordance with the transformation sequence principle.
Exploration of the Transition from Harrison Type-A Kinetics to Type-B Kinetics Regimes in Grain Boundary Diffusion
Authors: Belova Irina V. , Murch Graeme E.
Published: March 2009

We model the grain boundary tracer diffusion problem by constructing a 3D structure
consisting of cubic grains each of equal volume. We build the structure in such a way that no four
cubes have a common edge. It is shown that the transition point between Harrison Type-A and
Type-B kinetics regimes occurs at a diffusant diffusion length roughly an order of magnitude
smaller than for the extensively studied case of parallel grain boundary slabs. For two dimensional
squares the transition point occurs at a diffusion length roughly a factor of five smaller than for
parallel grain boundary slabs. Thus we can draw the conclusion that dimensionality and geometric
shape are both important factors in the parametric analysis of the grain boundary diffusion problem.
Defect-Induced Photoluminescence of Powdered Silica Glass
Authors: Pizani Paulo S. , Joya M.R. , Pontes F.M. , Santos L.P.S. , Godinho Jr M. , Leite E.R. , Longo Elson
Published: March 2009

Visible photoluminescence was generated in standard soda-lime-silica glass powder,
mechanically milled in a high-energy attrition mill. The broad emission band maximum shows a
linear dependence on the exciting wavelength, suggesting the possibility to tune the PL emission.
The photoluminescence was attributed to defect generation related to unsatisfied chemical bonds due
to the high surface area. Raman scattering and ultraviolet-visible optical reflectance measurements
corroborate this assertion. Transmission electron microscopy measurements indicate that the powder
is composed by nanocrystallites with about 10-20 nanometers immersed in an amorphous media.
Estimation of the Rate of Hydrogen Penetration in a Welded API 5L Steel Pipe
Authors: Plascencia Gabriel , Jaramillo David , Hernández Felipe , González Jorge Luis
Published: March 2009

Hydrogen embrittlement is a common problem for the integrity of oil conducting pipes.
In this work, we estimate the rate of hydrogen penetration into an API 5L steel pipe welded by
electric arc. The hydrogen penetration was estimated by means of data taken from ultrasonic
measurements. As expected, the steel pipe becomes more brittle as the hydrogen penetration rate
does so. A simple diffusion model was developed. The model confirms the strong dependency
between the rate of penetration and the mechanical damage to the material.
Analytical Solution of Unsteady Heat Diffusion within a Porous Copper Layer Deposited on Alumina Substrate and Subjected to a Moving Laser Beam
Authors: Belghazi Hamid , El Ganaoui Mohammed , Labbe J.C.
Published: March 2009

An analytical approach of transient heat conduction in a two layered material, in finite
dimensions within imperfect thermal contact, subjected to a moving Gaussian laser beam was
achieved. The result of this study allows on the one hand an easy access to the distribution and the
evolution of the temperature in both layers of the workpiece; on the other hand permits to clarify
the influence of the contact quality on the temperature gap at the interface. The effect of a porous
grannular deposit layer was also considered in this study. A design of electronic tracks by laser
cladding was studied as an application example in the surface treatment area; this model can be
also used to estimate the thermal contact resistance between layers.
Al-Li Surface Alloying in the Electrolytic Method
Authors: Foroutan I. , Rezaei Arash , Shokuhfar Ali
Published: March 2009

Surface alloying is a new method of surface treatment by which an element is diffused
into the surface of another element causing the formation of a solid solution on its surface. Using
this method, the problems of casting methods have been eliminated. In this method, the sample is
sunk into an aqueous solution and is connected to the cathode. Applying enough voltage, lithium
separated from lithium sulphat-sulfuric acid solution diffuses into the aluminum surface. The depth
of diffusion into the aluminum is measured to be 50 to 500μm according to the diffusion time which
is selected to be 1 to 24 hours. Experiments showed that the formed layer is very uniform. It was
also concluded from the experiments that hardness is increased extensively, with the maximum
value of 98HV, and fatigue life is increased by the factor 4. It was also shown that the toughness,
yield stress and ultimate tensile strength of samples are the same as those of pure aluminum.
Investigation of Homogenization Treatment in Al- Li- Cu- Zr Alloys
Authors: Rezaei Arash , Ahmadi Shahram , Shokuhfar Ali , Foroutan I.
Published: March 2009

Aluminum-Lithium alloys were developed as major replacements for existing aluminum
alloys to reduce the weight of aircraft and aerospace structures. Mechanical properties of Al-Li
alloys greatly depend on solidification conditions. Other than reducing the microsegregation,
homogenization treatment has other effects on the microstructure of Al-Li ingots. In this research,
effects of homogenization treatment at constant temperature (500°C) on the precipitation in the
microstructure of Al-1Li-3Cu-0.1Zr (wt %) and Al-2Li-3Cu- 0.1Zr (wt %) specimens have been
investigated. Results show that homogenization at 500°C for 24 hours not only increases the
hardness and phases precipitating in grain but also reduces microsegregation of Fe in grain boundaries.
Formation and Decomposition of Sol-Gel Synthesized Aluminum Titanate Nano Powders at the Presence of Fe2O3 Additive
Authors: Rezaie Hamid Reza , Sobhani M. , Naghizadeh Rahim
Published: March 2009

Full formation of aluminum titanate compound at low temperatures was obtained by solgel
method. With addition of various amount of Fe2O3 additive to tialite composition formation and
decomposition of tialite phase have been investigated. X-ray diffraction (XRD), simultaneous
thermal analysis (STA) and scanning electron microscopy (SEM) analysis showed that the
formation of nano tialite at low temperatures (around 950oC) was improved at the presence of
additive and decomposition rate of aluminum titanate to α-Al2O3 and TiO2 (Rutile) in sample with
5%wt Fe2O3 was controlled with formation of Al2TiO5-Fe2TiO5 solid solution.
Diffusion of Refractory Elements in Ni—X—Y (X, Y: Co, Re, Ru, W) Ternary Alloys
Authors: Sakurai Shingo , Mabruri Efendi , Murata Yoshinori , Koyama Toshiyuki , Morinaga Masahiko
Published: March 2009

Ni-based superalloys are strengthed by refractory elements such as Re, Ru and W [1].
Thus, the information on the interdiffusion coefficient as well as the thermodynamic interaction
between the refractory elements is important for the future alloy design. In this study,
interdiffusion coefficients of the refractory elements in Ni-X-Y (X, Y=Co, Re, Ru, W) ternary
systems were estimated by a series of experiments.
In the all systems studied in the present works, the main interdiffusion coefficients were much
larger than the cross interdiffusion coefficients. In some systems, two cross interdiffuion
coefficients had opposite signs each other. For example, in Ni-Co-Ru system, the main
interdiffusion coefficients are 2.7 10 14
~ Ru = × −
CoCo D and 15 6.8 10
~ Ru = × −
RuRu D , while the cross
interdiffusion coefficients are 16 6.6 10
~ Ru = − × −
CoRu D and 16 8.9 10
~ Ru = × −
RuCo D at 1523K.
In Ni-Co-Ru and Ni-Re-Co systems, the activation energies and frequency factors for two main
interdiffusion coefficients. For example, Q (kJ ) Co = 268 , 5 ( 2 1 )
0( ) 4.4 10 D = × − m s − Co ,
3 ( 2 1 )
0( ) 2.9 10 D = × − m s − Ru in Ni-Co-Ru system.
Synthesis of ZnO Nanoparticles via Sol-Gel Process Using Triethanolamine as a Novel Surfactant
Authors: Shokuhfar Ali , Samei Javad , Esmaielzadeh Kandjani A. , Vaezi Mohammad Reza
Published: March 2009

Current researches show a growing interest in Zinc Oxide (ZnO) nanoparticles. ZnO is a
semiconductor with a wide direct band gap of 3.37 eV and a large exciton binding energy of 60
meV at room temperature. Several methods have been developed in order to synthesize ZnO
nanoparticles. Chemical methods, among them sol-gel process, are more convenient. Sol-gel is
common for producing metal oxide nanoparticles because of its simplicity, cheapness and high
quality products. In this research ZnO nanoparticles were prepared via the sol-gel process.
ZnAc2.2H2O as precursor and TEA (Triethanolamine) as a novel surfactant were used in a
methanolic solution. MEA (Monoethanolamine) and DEA (Diethanolamine) have been highly used
before. In this research, solutions with different weight ratios of ZnAc to TEA (1:2, 1:1 and 2:1)
were obtained. After drying, all samples were calcinated at 500 °C for 1 hr. Obtained nanoparticles
were characterized with the hope of achieving better properties.
Microstructure Characterization by EBSD of Hot Rolled High-Silicon Steel
Authors: Rodriguez-Calvillo Pablo , Salazar N. , Schneider Juergen , Houbaert Yvan
Published: March 2009

Non oriented electrical steels are soft magnetic materials used in the core of electrical
motors. No preferential anisotropy of the electrical texture in the rolling plane is desired. Nowadays
these special steels are mainly alloyed with Si, Al and some additives to improve the magnetic
properties and to reach a good of formability. For (Si, Al)-concentrations higher than 2 wt.% the α-
γ-α phase transformation is suppressed, resulting in a bcc crystalline structure from liquidus to
room temperature. These electrical steels, which will be discussed in the paper, exhibit the lowest
values of the magnetic losses.
Hot rolling of FeSi electrical steels has been found to be one of the fundamental steps in
producing these materials with optimum properties. The resulting properties, as well known, are
determined by the type of magnetic textures and the structural inhomogeneities. Electron
Backscattered Diffraction (EBSD) is a reliable tool for microstructural and texture characterization
of different materials. Two compositions of electrical steel are studied by optical microscopy and
EBSD, with special attention paid to characterize the grain morphology and its texture through
thickness.
Diffusion of Water in Chestnut Fruits during Drying and Rehydration Processes at Different Temperatures
Authors: Moreira Ramón , Chenlo Francisco , Chaguri L. , Fernandes Christiana
Published: March 2009

Many food materials must be dried in order to decrease its water activity and to increase
the shelf-life. Also, rehydration operation must be carried out as previous step before consumption.
Both operations are commonly employed in some industrial chestnut processing. These processes
can be carried out at different temperatures and in all cases the quality of the final product can be
affected. In this work, convective drying with hot air is the employed method for water removal and
rehydration is carried out by immersion of chestnut in water. In both cases, mass transfer processes
are governed by water diffusion in the bulk of the solid. The aim of this work is to determine
experimentally the drying and rehydration kinetics of chestnut samples at different conditions of
temperature and moisture content. Obtained data are modeled with a diffusional model taking into
account volume variations and the corresponding values of the coefficients of diffusion of water are
obtained. Analysis of the results indicates that drying/rehydration rates increase with temperature
and rehydration kinetics are also depending on the initial moisture content of chestnut. Finally,
leaching flow during rehydration is only important at high temperature due to starch gelatinization
processes.
Development of Porous Ceramics for Gas Burners
Authors: Olhero Susana M.H. , Delgado João M.P.Q. , Ferreira José Maria F. , Pinho C.
Published: March 2009

The present work aims to develop porous ceramic plates based on cordierite, using the
polymer foam replication method, to be used for gas burners. Ceramic foams were produced by
coating polyurethane foams of different pore sizes with ceramic powders dispersed in aqueous
slurries. The final porous structures were shown to depend on the structure of the original polymer
sponge and on the details of the fabrication procedure. However, a suitable process control enabled
to obtain a close relation between the final properties and the template polymer characteristics. The
performance of the porous cordierite plates, with different pore size distributions, as medium
burners was tested and compared by measuring the pressure drop in the burner against the air flow
rate. It could be concluded that good performance is achieved with the higher porous materials due
to its higher porosity fraction, and more suitable pore size range.
Atomic-Migration-Controlled Processes in Intermetallics
Authors: Abdank-Kozubski Rafał Leszek , Biborski Andrzej , Kozłowski Mirosław , Goyhenex Christine , Pierron-Bohnes Veronique , Alouani Mebarek , Rennhofer Marcus , Malinov Savko
Published: March 2009

Chemical ordering kinetics in L10- and B2-ordered AB binary intermetallics was
simulated by means of Monte Carlo (MC) technique implemented with vacancy mechanism of
atomic migration. While vacancy concentration is usually much lower than the antisite defect
concentration in L10-ordered systems, triple defects are generated in particular B2–ordered systems.
The latter definitely affects the chemical ordering process and requires that full thermal vacancy
thermodynamics is involved in B2-ordering simulations. The study on L10-ordered binaries was
dedicated to FePt thin layers considered as a material for ultra-high-density magnetic storage media.
Metastability of the L10 c-variant with monoatomic planes parallel to the layer surface and off-plane
easy magnetization was revealed. Thermal vacancy formation in B2-ordered binaries was modelled
by implementing a mean-field Hamiltonian with a specific formalism of phase equilibria in a latticegas
composed of atoms and vacancies. It was demonstrated that for particular pair-interaction
energetics, equilibrium concentrations of vacancies and antisites result mutually proportional in
well-defined temperature ranges. The MC simulations of B2-ordering kinetics involved the
modelled equilibrium vacancy concentration and reproduced the experimentally observed low rate
of the process.
The Effect of Point Defects Interaction on Hydrogen Atom Diffusion in FCC- and BCC-Metals
Authors: Selezneva Liudmila V. , Nazarov Andrei V.
Published: March 2009

This work is devoted to simulation of potential barrier spectrum for hydrogen atom and
vacancy jumps in fcc- and bcc- metals taking into account the mutual effect of the point defects on
the potential barrier spectrum and as a result the effect on complex defect diffusion in bcc- and fccmetals.
The molecular static and the Monte Carlo methods are used. The developed model allows us
to determine a diffusion coefficient of the impurity atom depending on temperature and other
parameters. The simulation of point defect random walk in lattice on the basis MC-method and
potential barrier spectrum has gave an impulse toward an understanding of hydrogen motion on the
atomic scale in metals, which is required to determine such important parameters as the diffusion
coefficient of H. As well it allows us to understand reasons of more complicated behaviour of H in
realistic metal in comparison with perfect metal.