bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure of Nitrided Layer Formed on Austenitic Stainless Steel by a New Gas Nitriding Process
Authors: Fujikawa Hisao , Watanabe Takanori
Published: March 2009

The nitrided layer formed on Type 304 steel after gas nitriding was studied using TEM
and so on.
(1) Dependency of the nitriding temperature and time on the depth of the nitrided layer was studied.
The following equation was obtained. L2=8.7*108*EXP(-146,000/RT)*t
(2) Nitrided layer formed at both 570°C for 3 hrs and 410°C for 48 hrs had high density of
dislocation, stacking fault and lattice strain.
(3) Nitrided layer formed at 570°C was mainly composed of є-Fe3N, and had much Fe4N and CrN.
(4) On the other hand, the nitrided layer formed at 410°C was mainly composed of S-phase, є-Fe3N
was not detected and Fe4N and CrN were very little. N content in the nitrided layer formed at
410°C was about 7-8 mass%.
(5) Nitrided layer formed at 410°C showed good corrosion resistance.
Point Defects Characterization in Quenched δ-Ni2Si as Deduced from Isothermal Magnetic Susceptibility Measurements
Authors: Jennane Adib , Sassi O. , Aride J. , Bernardini Jean , Moya Gérard
Published: March 2009

The behaviour of quenched defects in Ni2Si compound is studied by isothermal
susceptibility magnetic measurements. In the range of temperature 553-593K, where an
enhancement of susceptibility has been previously detected by isochronal measurements, an
activation energy (EA=2.5 ± 0.2 eV) is determined. This value is in agreement with the break-up of
3D nickel vacancy clusters, formed at lower temperatures, and the subsequent formation of nickel
rich defects via the released vacancies.
Microstructural Analysis of Compressive Zr62Cu17Ni13Al8 Bulk Amorphous Alloy
Authors: Liu Hong Yan , Shin Kee Sam , Yoo Jung Hoon , Dong Ji Ling , Huynh Quoc Bao , Yu Hui , Lee Chan Gyu , Na Young Sang , Cho Kyung Shik , Lee Jong Hoon
Published: March 2009

Zr62Cu17Ni13Al8 in the supercooled liquid state is expected to be micro-formable at a
relatively low stress. We used X-ray diffraction (XRD), scanning electron microscopy (SEM),
transmission electron microscopy (TEM), and quantitative high-resolution TEM (HRTEM) to
investigate the microstructures of Zr62Cu17Ni13Al8 amorphous alloy after compression test. The
alloy exhibited the homogeneous amorphous microstructure with some crystalline phases dispersed
in the matrix. According to the XRD results, under the certain strain rate in the supercooled liquid
state, the alloy showed higher crystallization at the higher heat treatment temperature. However, at
the same heat treatment temperature, the alloy deformed under low strain rate showed higher
crystallization. The β crystalline phase particles with spherical shape were detected by SEM and
TEM. The sample with higher strain rate and temperature showed longer shear bands. Nano-voids
formed by the coalescence of excess free volume in shear bands were investigated by quantitative
HRTEM. Compared with the undeformed area, in the shear band, nanovoids were identified in the
deformed area through quantitative HRTEM simulation.
Finite Element Verification of Transmission Conditions for Thin Reactive Heat-Conducting Interphases
Authors: Öchsner Andreas , Miszuris Wiktoria
Published: March 2009

Imperfect transmission conditions modelling a thin reactive 2D intermediate layer
between two bonded materials in a dissimilar strip have been derived and analytically analysed
in another paper of this issue. In this paper, the validity of these transmission conditions for
heat conduction problems has been investigated due to the finite element method (FEM) for
two formulations of a reactive layer: namely, based on a constant and a temperature-dependent
source or sink formulation. It is shown that the accuracy of the transmission conditions is
excellent for the investigated examples.
Magnetically Stabilized and Fluidized Beds: Heat and Mass Transfer
Authors: Augusto Paulo A. , Castelo-Grande Teresa , Estévez Angel M. , Barbosa Domingos , Rodriguez Jesus M. , Álvaro Audelino , Sanchéz Javier
Published: March 2009

Research and applications of magnetically stabilized and fluidized beds begun several
decades ago, and have maintained their rate of interest during all these years. During last years their
applications was diversified, and the application of these beds in the processing of biological
materials and in environmental issues has nowadays focused the main attention within this area. In
this work we present a brief review of magnetically fluidized and stabilized beds, mainly
concerning their theoretical background, heat and mass transfer topics, some industrial and
laboratorial setups and applications.
Parametric Analyses of the TROI Experimental Results by Using the TEXAS-V Code
Authors: Park I.K. , Kim J.H. , Min B.T. , Hong S.H. , Kim H.D. , Hong S.W.
Published: March 2009

The TEXAS-V code was tuned for TROI-13 and used for analyzing the parametric
findings of the TROI experiments. The calculations for the melt composition are relatively similar
to the TROI experimental results, in which the melt composition has quite an effect on the steam
explosion occurrence probabilities and a steam explosion itself. The void fraction difference due to
a particle size difference appears to cause this composition dependency of a steam explosion. The
water depth effect in the TEXAS-V code seems to be consistent with the TROI experiments to some
degree. The water area effect of the TEXAS-V calculations isn’t exactly harmonious with that of the
TROI experiments. This indicates that TEXAS-V code as a 1-dimensional code or as a numerical
steam explosion has a limitation in estimating an area effect. The experimental information on the
particle size and the void fraction during mixing is very helpful for a verification of this relation.
Growth Kinetics of Al-Si-Fe Intermetallics during Hot Dipping of Steel
Authors: Rodriguez-Calvillo Pablo , Rouco R. , Houbaert Yvan
Published: March 2009

Electrical steels are used in flux carrying machines, divided in grain oriented and non
oriented electrical steels mainly used in transformers and electrical motors, respectively. Their
industrial production is not always easy due to the alloying elements which produce brittle order
structures in the steel. Therefore hot dipping was found to be an alternative way of producing
electrical steel with a high concentration of Al and/or Si: in a first series of experiments different
steel substrates were coated by immersion in an Al + 23 m.-% Si hypereutectic alloy, followed by a
high temperature diffusion annealing.
The present contribution reports on the growth kinetics of Al-Si-Fe intermetallics formed during
the dipping process in a hypoeutectic Al – 5 m.-% Si bath of Fe-substrates with 3 m.-% Si,
previously cold rolled to different thickness. This bath composition allows a liquid phase at
temperatures lower than the hypereutectic one with 23 m.-% Si and also less amount of eutectic
formation. No Na-addition was made to the bath (the occurrence of a needle-like morphology of the
Al-Si eutectic was not relevant for these experiments), furthermore this element might lower the
magnetic properties of the steel. The preheating of samples and bath temperatures were not varied
and set to 670°C. Short dipping times of 1 to 60 sec. were applied. The different layers formed were
characterised by Scanning Electron Microscopy (SEM), using the Back Scattered Electron (BSE)
detector and Energy Dispersive Spectroscopy (EDS).
Chronoamperometric Determination of Diffusion Coefficients for Borohydride Anions in Sodium Hydroxide Solutions
Authors: Santos Diogo M.F. , Sequeira César A.C.
Published: March 2009

Chronoamperometry is carried out with a Au disc electrode in alkaline sodium
borohydride solutions of varying concentrations and temperatures. By selecting conditions for
which the borohydride oxidation is controlled by diffusion, it was possible to deduce diffusion
coefficients and activation energies for borohydride concentrations ranging from 0.03 M to 0.12 M,
and temperatures ranging from 25 to 65 °C. The estimated parameters were compared with other
values reported in the open literature.
On the Features of Ultramicroelectrodes
Authors: Santos Diogo M.F. , Lobo Rui F. M. , Sequeira César A.C.
Published: March 2009

Ultramicroelectrodes offer several unique characteristics which enable new types of
electrochemical measurements. These include: 1) small size; 2) minimisation of iR effects; 3) rapid
response; and 4) steady-state response at moderate times. These features enable experiments as
diverse as in vivo electrochemistry, electrochemistry in pharmacology, nanoelectrochemistry,
electrochemistry in solvents such as benzene, microsecond electrochemistry, and flow-rate
independent electrochemistry. Thus, it is apparent that the use of ultramicroelectrodes has become a
rapidly growing area of interest. In this paper, the attributes of ultramicroelectrodes, its construction,
the equations of diffusion, and key applications of electrochemistry at ultramicroelectrodes, are
analysed.
High-Temperature Oxidation of Fe- Si Alloys in the Temperature Range 900-1250°C
Authors: Suarez Lucia , Schneider Juergen , Houbaert Yvan
Published: March 2009

Exposure of metals and alloys to high temperatures leads to the formation of oxide
scales, with a large impact on surface quality. The most important features of the oxide layer are its
thickness, composition, structure, adherence and coherence. Temperature, time, gas atmosphere and
chemical composition determine the growth of oxide layers. In this paper, the characteristics of the
high temperature oxidation properties of Fe-Si alloys are discussed in terms of oxide growth
mechanism, kinetics and phase morphology.
The oxidation kinetics of different Fe-Si alloy steels in air, its scale structure and composition
were investigated over the temperature range 900-1250°C. Oxidation experiments were performed
in air, to analyse the oxidation process. Experiments were carried out in an electric furnace at
temperatures ranging from 900 to 1250°C, for times between 16 and 7200s. Thus treated specimens
were characterised by metallography and their scale thickness was measured by optical microscopy.
Scale morphology was studied and scale composition confirmed by EDS (Energy Dispersive
Spectroscopy) and EBSD (Electron Backscattered Diffraction) analysis.
Results show that high temperature oxidation of Si- alloys presents the classic three layered
oxide scale. On the grain boundaries in the scale, iron-silicate was found. Observations show a Sienrichment
at the scale –metal interface. This enrichment is present in the form a mixed wustite-iron
silicate (fayalite) phase, FeO-Fe2SiO4. A very rapid build-up of oxide occurs when a liquid phase,
due to the wustite-fayalite eutectic, is present in the surface of the steel.
Diffusion of 8Li Short-Lived Radiotracer in Li Ionic Conductors of NaTl-Type Intermetallic Compounds
Authors: Sugai Hiroyuki , Sataka Masao , Okayasu Satoru , Ichikawa Shin Ichi , Nishio Katsuhisa , Mitsuoka Shinichi , Nakanoya Takamitsu , Osa Akihiko , Sato Tetsuya , Hashimoto Takashi , Jeong Sun Chan , Katayama Ichiro , Kawakami Hirokane , Watanabe Yutaka , Ishiyama Hironobu , Imai Nobuaki , Hirayama Yoshikazu , Miyatake Hiroari , Hashimoto Takanori , Yahagi Masahito
Published: March 2009

Non-destructive and on-line Li diffusion experiments in Li ionic conductors are
conducted using the short-lived !-emitting radiotracer of 8Li. The radiotracers produced as an
energetic and pulsed ion beam from TRIAC (Tokai Radioactive Ion Accelerator Complex) are
implanted into a structural defect mediated Li ionic conductor of NaTl-type intermetallic
compounds ("-LiGa and "-LiIn). The experimental time spectra of the yields of !-particles are
compared with simulated results and Li diffusion coefficients in the intermetallic compounds are
extracted with an accuracy of ±10%. The diffusion coefficients obtained for "-LiGa with Li content
of 43-54 at.% are discussed in terms of the interaction between Li-ion and the structural defects in
the specimen, compared with the cases of "-LiAl and "-LiIn. The nonlinear Li-content dependency
of Li diffusion coefficients for "-LiGa suggests that the Li diffusion with the Li-deficient region is
obstructed by the defect complex composed of vacancies at the Li sites.
Mass Transfer Coefficients during Steel Decarburization in a RH Degasser
Authors: Tavares Roberto Parreiras , Nascimento André Afonso , Pujatti Henrique Loures Vale
Published: March 2009

The RH process is a secondary refining process that can simultaneously attain significant
levels of removal of interstitial elements, such as carbon, nitrogen and hydrogen, from liquid steel.
In the RH process, the decarburization rate plays a very important role in determining the
productivity of the equipment. The kinetics of this reaction is controlled by mass transfer in the
liquid phase.
In the present work, a physical model of a RH degasser has been built and used in the study of the
kinetics of decarburization. The effects of the gas flow rate and of the configurations of the nozzles
used in the injection of the gas have been analyzed. The decarburization reaction of liquid steel was
simulated using a reaction involving CO2 and caustic solutions. The concentration of CO2 in the
solution was evaluated using pH measurements.
Based on the experimental results, it was possible to estimate the reaction rate constant. A
volumetric mass transfer coefficient was then calculated based on these rate constants and on the
circulation rate of the liquid. The logarithm of the mass transfer coefficient showed a linear
relationship with the logarithm of the gas flow rate. The slope of the line was found to vary
according to the relevance of the reaction at the free surface in the vacuum chamber. A linear
relationship between the volumetric mass transfer coefficient and the nozzle Reynolds number was
also observed. The slopes of the lines changed according to the relative importance of the two
reaction sites, gas-liquid interface in the upleg snorkel and in the vacuum. At higher Reynolds
number, the reaction in the vacuum chamber tends to be more significant.
Diffusion of Refractory Elements in Ternary Iron Alloys
Authors: Yamashita Kouji , Kunieda Tomonori , Takeda Koutarou , Murata Yoshinori , Koyama Toshiyuki , Morinaga Masahiko
Published: March 2009

Interdiffusion coefficients of the refractory elements in Fe-W-Re and Fe-Cr-X (X=Mo,
W) ternary alloys have been measured on the basis of the modified Boltzmann-Matano method for
ternary system. Both the cross interdiffusion coefficients, Fe
ReW
~D
and Fe
WRe
~D
were negative in
Fe-W-Re ternary alloys. This result indicates that attractive interaction exists between W and Re
atoms in iron alloys [1]. This is consistent with our previous experimental results that Re suppresses
W diffusion in Fe-15Cr alloy [1]. In addition, the value of cross interdiffusion coefficient Fe
CrW
~D
was positive in Fe-Cr-W diffusion system, whereas Fe
MoCr
~D
was negative in Fe-Cr-Mo diffusion
system.
Investigation of Sulfur Transition through Metal-Slag Phase Boundary in Natural Moving Conditions
Authors: Radune Maya , Radune Alex , Assous F. , Zinigrad Michael , Eliezer D.
Published: March 2009

A mathematical model of sulfur transfer in a moving metal and slag melts has been
developed. Sulfur is transported simultaneously both by diffusion and by laminar natural convection
of the melting metal and oxide fluxes. The diffusion of sulfur is described by the 2nd Fick's law. We
have computed the distribution of sulfur in the metal and slag phases and the concentration changes
of sulfur in the volume of the metal and slag phases, both functions of space and time. Numerical
results are provided to show the validity of this approach.
Numerical Modelling of the Heat and Mass Transfer in a Channel with Hygroscopic Walls
Authors: Ruivo C.R. , Costa J.J. , Figueiredo A.R.
Published: March 2009

In this paper the numerical modelling of the behaviour of a channel of a hygroscopic
compact matrix is presented. The heat and mass transfer phenomena occurring in the porous
medium and within the airflow are strongly coupled, and some properties of the airflow and of the
desiccant medium exhibit important changes during the sorption/desorption processes. The adopted
physical modelling takes into account the gas side and solid side resistances to heat and mass
transfer, as well as the simultaneous heat and mass transfer together with the water
adsorption/desorption process in the wall domain. Two phases co-exist in equilibrium inside the
desiccant porous medium, the equilibrium being characterized by sorption isotherms. The airflow is
treated as a bulk flow, the interaction with the wall being evaluated by using appropriated
convective coefficients. The model is used to perform simulations considering two distinct values
of the channel wall thickness and different lengths of the channel. The results of the modelling lead
to a good understanding of the relationship between the characteristics of the sorption processes and
the behaviour of hygroscopic matrices, and provide guidelines for the wheel optimization, namely
of the duration of the adsorption and desorption periods occurring in each hygroscopic channel.
A New Approach to Measure Diffusion Coefficients at Different Temperatures – A Simple Experiment
Authors: Delgado João M.P.Q.
Published: March 2009

The present work describes the mass transfer process between a moving fluid and a
slightly soluble plane surface buried in a packed bed, in alignment with the direction of flow. The
bed of inert particles is taken to have uniform voidage. The elliptic equation resulting from a
differential mass balance was solved numerically over a wide range of the relevant parameters and
the resulting values of Sherwood number are seemed to depend only of the Peclet number.
Experiments measurements of mass transfer in water were performed on the dissolution of plane
surfaces of 2-naphthol and benzoic acid at temperatures that differ significantly from ambient value.
The soluble plane surfaces used in the experiments were made of either 2-naphthol or benzoic acid
and the range of temperatures covered were 278 to 368 K, for the dissolution of 2-naphthol, and 278
to 338 K, for benzoic acid in water. The results illustrate a simple and accurate method for the
measurement of the coefficient of molecular diffusion of slightly soluble solutes.
Experimental Study of Free Convection from a Vertical Flat Plate in Porous Media
Authors: Aldabbagh L.B.Y. , Sharifpur Mohsen , Zamani Mahdi
Published: March 2009

A set of experiments is done to study the phenomenon of free convection heat transfer
from an isothermal vertical flat plate embedded in a saturated porous medium in steady state
condition. The porous medium consisting of 0.8 cm spheres. The aspect ratio of the isothermal flat
plate, H/W, is equal to 2. Where H is the height and W is the width of the vertical plate. The
investigations were cared out for Darcy modified Rayleigh number between 100 and 500. The
results indicate that heat transfer increases linearly with increasing the Darcy modified Rayleigh
number. In addition, the present results are in good agreement with the higher-order boundary layer
theory obtained by Cheng and Hsu [1].
Effect of Bond Coat Diffusion on Adhesion Behaviour of Hard Alloy Powder NiCrBCSi (Fe) Coatings Thermally Sprayed on 60CrMn4 Steel
Authors: Abdi S. , Malki B. , Lebaili S.
Published: March 2009

The object of the present work is to study the spraying of poly-powders nickel bases
containing Cr, Si, C and B elements addition with variable percentage of iron, deposited on a steel
substrate by oxy fuel thermal spraying. The substrate surface was previously treated by Al–Ni bond
coat and post–annealing at 650°C. The spraying powder and coating micro structure were
investigated by combination of X-ray diffraction, electron microprobe and scanning electron
microscope coupled to an analyzer energy dispersive x-ray. The adherence to substrate was
determined by using shear test for adhesion. The result of this study was to investigate to compare
potentials of HVOF sprayed NiCrBCSi and satellite 6 coating for a possible to replacement of hard
chromium plating. A good adherence of coating NiCrBCSi (Fe) on steel substrate is explained by
formation of large diffusion zone in interface after annealing and by the nature of the structure
deposit duplexes.
Atomic Mechanism of Carbon Diffusion in Cementite
Authors: Evteev Alexander V. , Levchenko Elena V. , Belova Irina V. , Murch Graeme E.
Published: March 2009

Molecular dynamics is employed to investigate carbon diffusion in cementite. An
approximation that carbon atoms can interact with each other only indirectly (via neighbouring iron
atoms) is used. The interstitial mechanism of carbon diffusion in cementite is elucidated. The formation
energy of defects (a carbon atom on an interstitial position and a vacant site on a regular carbon position)
as well as the migration energy of carbon atoms are estimated in the temperature range 1273–1373 K.
Activation Enthalpy of Dislocation Migration in Aircraft (Aerospace) (2024) Alloy by Positron Spectroscopy
Authors: Abdel-Rahman M.A. , Abdallah M.S. , Hassan N.M. , Badawi Emad A.
Published: March 2009

Positron annihilation lifetime is one of the most important nuclear techniques, used to
study the isochronal and isothermal annealing in one of the most important
engineering aluminum alloys which is 2024 alloy. Samples of 25 % deformation have
been used for these studies. Two recovery stages during the isochronal annealing [1]
were observed which were ascribed to the recovery of point defects and dislocations
introduced by the deformation. The isothermal annealing measurements were
performed at 583, 603, 623 and 643 K from which the activation energy obtained was
1.24 ± 0.08 eV.
Self-Organization Behavior of Sub-Micron CdO Grains Grown during Vapour-Solid Transition
Authors: Zhang Ji Zhong , Wang Wei Qiang , Li Na
Published: March 2009

Various deposits of CdO grains were observed on the surface of N 100 silicon
crystals heated at 580 °C and 620 °C for 1 hour in an evaporation-deposition device,
respectively. The ball-shaped crystals, and regular-prism-shaped crystals were found
on top of bush-like long crystals. Two types of CdO self-organization aggregates
were also observed, that is, regular circular-shaped dense aggregate and long-chainshaped
aggregate. The self-organization aggregates were composed of numerous submicron
CdO grains. The relationship between self-organization aggregates and
surface defects of virgin N 100 silicon crystal was investigated. The results showed
that the CdO self-organization aggregates were related to surface defects of the virgin
N 100 silicon crystal, and a defect induced aggregation (DIA) model is suggested.
δ-Hydride Habit Plane Determination in α-Zirconium at 298 K by Strain Energy Minimization Technique
Authors: Singh R.N. , Ståhle Per , Banks-Sills Leslie , Ristinmaa Matti , Banerjee S.
Published: March 2009

Hydrogen in excess of solid solubility precipitates as hydride phase of plate shaped
morphology in hcp α-Zr with the broad face of the hydride plate coinciding with certain
crystallographic plane of α-Zr crystal called habit plane. The objective of the present investigation
is to predict the habit plane of δ-hydride precipitating in α-Zr at 298 K using strain energy
minimization technique. The δ-hydride phase is modeled to undergo isotropic elasto-plastic
deformation. The α-Zr phase was modeled to undergo transverse isotropic elastic deformation but
isotropic plastic deformation. Accommodation strain energy of δ-hydride forming in α-Zr crystal
was computed using initial strain method as a function of hydride nuclei orientation. Hydride was
modeled as disk with round edge. Contrary to several habit planes reported in literature for δ-
hydrides precipitating in α-Zr crystal, the total accommodation energy minima at 298 K suggests
only basal plane i.e. (0001) as the habit plane.
Effect of Cu Addition on Nanocrystallization Behavior in a Co-Based Soft Magnetic Metallic Glass
Authors: Srivastava A.P. , Srivastava Dinesh , Suresh K.G. , Dey G.K.
Published: March 2009

Microstructure and magnetic properties of a nanocrystalline soft magnetic material
having composition Co64.5 Fe3.5 Si16.5 B13 Ni1.5 Cu1 has been studied. Amorphous ribbon could be
produced by melt spinning unit. DSC analysis showed four distinct crystallization events. Heat
treated samples were characterized using XRD and TEM techniques. Co2B, and CoB phases were
found to crystallize before magnetic phase a−Co. Addition of copper was proved to have adverse
effect on soft magnetic properties.
Selection of Lattice Invariant Shear in Dilute Zr-Nb Alloy for bcc-hcp Martensitic Transformation
Authors: Srivastava Dinesh , Dey G.K. , Banerjee S.
Published: March 2009

The morphology and substructure of martensite is considered to arise from the lattice
invariant shear (LIS) associated with the transformation and this may be slip, twinning or both. Out of
the several possible slip shears and twin modes only a few satisfy invariant plane strain criteria of the
phenomenological theory of martensite (PTMC). On the basis of crystallographic and energetic criteria,
a simple model has been proposed for determining the factors which influence the selection of the
preferred LIS mode. In the present work, it is found that for b ® a' martensitic transformation in Zr-2.5
wt%Nb alloy, the preferred slip system is {1101}a'<2113>a' and the preferred twin system is
{1101}a'<415 3>a'.
Development of a Thermodynamic Criterion to Predict the Alloy Compositions for Amorphous and Nanocrystalline Phase Formation during Mechanical Alloying
Authors: Das N. , Pabi S.K. , Kulkarni U.D. , Murty B.S. , Dey G.K.
Published: March 2009

Recent studies indicate that the existing criteria for amorphous phase formation are
not precise. This study emphasizes that the extent of deviation from the linear relationship of the
chemical contribution to enthalpy of the solid solution with the enthalpy difference between the
amorphous phase and the constituent elements is a measure of tendency to bypass amorphous phase
formation. Mechanical alloying experiments on a number of compositions in Al-Ni-Ti system
showed that the compositions, not following the aforesaid relation, yield partial or no
amorphization.
Diffusion in Cu(Al) Solid Solution
Authors: Laik A. , Bhanumurthy K. , Kale G.B.
Published: March 2009

The solid state diffusion characteristics in the Cu(Al) solid solution phase, was
investigated in the temperature range of 1023–1223 K using single phase bulk diffusion couples
between pure Cu/Cu- 10 at.% Al. The interdiffusion coefficients, D, were calculated using
Boltzmann–Matano method and Hall’s method from the concentration profiles of the couples that
were determined using EPMA. The interdiffusion coefficients (D) calculated ranges between 1.39 X
10−14 and 3.97 X 10−13 m2/s in the temperature range of 1023 to 1223 K. The composition and
temperature dependence of D were established. The activation energy for interdiffusion varies from
123.1 to 134.2 kJ/mol in the concentration range 1 at. % ≤ CAl ≤ 9 at. %. The impurity diffusion
coefficient of Al in Cu is determined by extrapolating the interdiffusion coeffficient values to
infinite dilution of the alloy i.e CAl →0 and its temperature dependence was also established. The
activation energy for impurity diffusion of Al in Cu was found to be 137.1 kJ/mol.
Recrystallization Kinetics in 17Cr 1Mo Ferritic Steel
Authors: Mungole M.N. , Trivedi Prakash C. , Sharma Satyam , Sharma R.C.
Published: March 2009

The recrystallization kinetic of 17Cr 1Mo ferritic steel was studied using 60% cold rolled
samples. The recrystallization was carried out at 750 , 800 and 9000C for 3, 5, 15, 30 and 60
minuets. The volume fraction of the recrystallized grains was used as a kinetic parameter. The
magnitude of time exponent “n” was much less than the ideal value because of the heterogeneous
recrystallization. The estimated activation energy for recrystallization “Q” was more as compared to
those for pure metals.
Dislocation Recovery in Casting Alloy by Positron Lifetime Technique
Authors: Abdel-Rahman M.A. , Abdallah M.S. , Kamel N.A. , Badawi Emad A.
Published: March 2009

Recovery behavior of 20% plastically deformation of casting AlSi11.35Mg0.23 in various stages of isochronal annealing has been investigated by positron Lifetime (LT). The experimental results show that the positron mean lifetime is a function of annealing temperature. Lifetime of the positron annihilating in perfect lattice is 187.3ps and in 20% deformed is 229.8 ps. There are two regions in the isochronal annealing, one of them relating to the point defect and the other to the dislocation. The activation enthalpy for the dislocation is calculated from the isothermal study in the dislocation region from (575-675) K by slow and fast cooling as 0.16±0.02 and 0.53±0.06 eV respectively.
Quantitative Concept for Morphological Stability Analysis of Liquid-Solid Interface in Rapid Solidification of Dilute Binary Alloys
Authors: Draissia M.
Published: March 2009

In this article, the liquid-solid interface solidification stability of dilute binary alloy systems during unidirectional (z) solidification was investigated. A new quantitative approach is proposed with (z-δ) as a variable to solve the equation of solute diffusion in the liquid, where δ is the real diffusion layer thickness.
Recrystallization Annealing of Cold Rolled 9Cr 1Mo Ferritic Steel Containing Silicon
Authors: Mungole M.N. , Surender M. , Balasubramaniam R. , Bhargava S.
Published: March 2009

9Cr-1Mo ferritic steel samples containing 0.2 and 0.5 wt % silicon in 40 % cold rolled state were recrystallize-annealed at 1100, 1200 and 1300 K. The grain growth and mechanical properties after recrystallization-annealing for 20 hr to 100 hr were investigated. No significant grain growth was observed even after 100 hr annealing at 1100 and 1200 K. The recrystallization-annealing at 1200 K resulted grains smaller in size than those at 1100 K. Annealing at 1300 K exhibited the enhanced grain growth with decorative microstructures. Initial annealing after cold rolling at 1100 K exhibited low hardness which further increased with annealing temperature. Annealing at 1100 K for 20 hrs exhibited low yield strength and ultimate tensile strength compared to those of as received samples. However, for 100 hrs annealing these properties remained nearly constant for 0.2 Si composition and increased marginally for 0.5 Si composition. Recrystallization-annealing exhibited improved ductility for both the compositions.
Diffusion in Very Dilute Zr-Fe Alloys
Authors: Pérez Rodolfo A.
Published: March 2009

The diffusion process in hcp Zr with low amounts of Fe being in solution or forming very dilute Zr-Fe alloys is analysed and discussed. The enhancement of the diffusion coefficient in alloys with increasing amounts of Fe is studied using both experimental and theoretical results. In contraposition with the assumption made in the literature that the Fe in solution in the hcp Zr lattice is the responsible, this enhancement seems to be more related with the total amount of Fe present in the samples. This idea is supported by measurements of Au diffusion in Zr with 50 to 150 gr/gr of Fe which shows increments in the diffusion coefficients even at the lower temperatures where the reported Fe solubility in -Zr is negligible.
Ab initio calculations using SIESTA and WIEN2k codes show several stable and meta-stable configurations for the Fe in the hcp Zr lattice in interstitial and off-centre positions, resembling the last ones a Zr3Fe like arrangement. These configurations are used in order to analyze the mechanism of both, self-diffusion enhancement and ultra-fast diffusion of Fe in -Zr.
Effects of Copper Powder Insert Layer on the Properties of Friction Welded Joints Between AlCu and AISI 4140 Structural Steel
Authors: Bouarroudj E. , Bouzidi Wahiba , Menchi O. , Abdi S.
Published: March 2009

The present investigation attempts to understand the friction welding characteristics of Aluminum alloy AlCu and steel AISI 4140. In spite, many trials were applied to achieve the sound weld zone of direct bonding between Aluminum and steel. The formation of intermetallic phase and crack in the near weld zone resulted in a lower tensile strength of joints relative to those of other welding technique. Therefore, to prevent intermetallic phase and crack formation at the interface, pure copper was used as insert powders for stress relief buffer layer. This study also envisages the influence of process parameters which include resident preform densities, friction pressure, upset pressure, and burn-off length on microstructure and mechanical properties of the welds. This work consolidates information on the aspects of diffusion joining of steel, copper and Aluminum component with wrought materials for practical execution. In the view point of tensile strength, the highest tensile strength between AlCu and AISI 4140 was acquired by using pure copper as insert powder.
Experimental and Numerical Analysis of the Nickel Deposition and Diffusion Using Plasma in a Confined Anode-Cathode Configuration
Authors: Cardoso Rodrigo Perito , Maliska A.M. , Maliska C.R.
Published: March 2009

This work presents a theoretical and experimental study of nickel deposition on iron samples at relatively high pressure using a pulsed DC glow discharge. The deposition process was conducted in conditions similar to that used for plasma sintering, using the confined anode-cathode configuration. The cathode was made from nickel commercially pure and the samples were made from interstitial free steel and sintered pure iron. The samples were characterized by mass weight gain, scanning electron microscopy and energy-dispersive X-ray microanalysis. The deposition process was mathematically modeled and the model was numerically solved using a conservative finite-volume method. The experiments demonstrated that the deposition occurs at a constant rate, with the mass flux changing linearly with the cathode voltage in the range of parameters considered. The results obtained from the diffusion model applied to the sample presented good agreement with the experimental values. Concerning the gas phase, the proposed model helped us to clarify some phenomenological aspects of the process. However, further studies, principally in the area of electrical discharges, are needed to permit a complete comprehension of this process.
Air Oxidation Kinetics Study of Zr58Nb3Cu16Ni13Al10 Bulk Metallic Glass
Authors: Huang Dong Ya , Zhao Xiang Jin , Zhang Tao , Ji Vincent
Published: March 2009

The isothermal oxidation behavior of Zr58Nb3Cu16Ni13Al10 bulk metallic glass (BMG) under dry air in the glassy state and the supercooled liquid state (SLS) was studied by the thermogravimetric method. The oxidation rate and thickness growth speed in the SLS were both hugely higher than in the glassy state. The oxidation kinetics of BMG in both states for 1.5 hours was different, the parabolic law was followed in the glassy state at 300°C and 350°C, contrarily the linear law was followed in SLS at 400 °C. After the oxidation for 126 hours in SLS, the oxidation kinetics possessed two stages, the linear stage and the parabolic stage. The diffusion of the Cu2+ ion and CuZr intermetallic alloys were detected by GIXRD.
Diffusion of Nitrogen in Ti-13V-11Cr-3Al Alloys
Authors: Grandini Carlos Roberto , Kamimura Emerson Haruiti , Martins José Roberto Severino , Sandim Hugo Ricardo Zschommler , Florêncio Odila
Published: March 2009

Metals with a bcc crystalline structure such as Ti-13V-11Cr-3Al alloys have their physical properties significantly changed through the addition of interstitial elements such as oxygen and nitrogen. These metals can dissolve substantial amounts of interstitial elements forming solid solutions. Mechanical spectroscopy measurements constitute a powerful tool for studying interactions of these interstitial elements with other elements that make up the alloy. From these measurements, it is possible to obtain information regarding diffusion, interstitial concentration, interaction between interstitials, and other imperfections of the crystalline lattice. In this paper, Ti-13V-11Cr-3Al alloys with several amount of nitrogen, in a solid solution, were studied using mechanical spectroscopy (internal friction) measurements. The results presented complex internal friction spectra which were resolved in a series of constituent Debye peaks corresponding to different interactions and interstitial diffusion coefficients. Pre-exponential factors and activation energies were calculated for nitrogen in theses alloys.
Defect Analyses of Deformed Zr-Cu-Ni-Al Bulk Metallic Glasses
Authors: Yoo Jung Hoon , Yoo Dae Hwang , Seo Jung Hwa , Dong Ji Ling , Na Young Sang , Cho Kyung Shik , Lee Jong Hoon , Shaislamov Ulugbek , Yang Jun Mo , Lee Chan Gyu , Shin Kee Sam
Published: March 2009

In Zr-Cu-Ni-Al bulk metallic glasses where there are no dislocations, localized plastic deformation in shear bands occurs largely by the formation and migration of defects such as voids, micropores, shear bands and local variations in composition. Thus, the investigation on defects is critical for the understanding and improvement of plastic deformation in metallic glasses. In this study, microstructures and nano defects in the Zr-Cu-Ni-Al BMGs are characterized by variety of techniques, such as X-ray diffractometry, high resolution transmission electron microscopy, scanning transmission electron microscopy and electron holography.
The influence of the Synthesis Conditions of NiCuZn Ferrites on their Microscopic Homogeneity
Authors: Sakellari D. , Tsakaloudi V. , Zaspalis V.T. , Polychroniadis Efstathios K.
Published: March 2009

The present work investigates the influence of the synthesis conditions of specific ferrites (Ni0,30Cu0.07Zn0,63)Fe2O4, prepared with the mixed oxide process, on their microstructural homogeneity. Segregation was found inside the grains, in the form of clustering or compositional modulation. Both types of segregation, which are not observed in all grains or all samples, seem to be related to the stress of the material as well as the specific orientation of the individual grains, where the segregation appeared. The reason for this assumption, which will be discussed, is that after annealing, where stress relaxation takes place, the segregation completely disappeared.
Transmission Conditions for Thin Reactive Heat-Conducting Interphases: General Case
Authors: Mishuris Gennady , Miszuris Wiktoria , Öchsner Andreas
Published: March 2009

Imperfect transmission conditions modelling a thin reactive intermediate layer be-
tween two bonded materials in a dissimilar strip are derived in this paper in most general
case extending results obtained previously in [1]. The interphase material is assumed to be
heat-resistant and situated in a thin rectangular domain between the main materials.
Specific Features of Jahn-Teller Structure Phase Transitions in Nanocrystalline Materials
Authors: Fishman Anatoly Yakovlevich , Ivanov M.A. , Petrova S.A. , Tkachev Nickolai , Vykhodets Vladimir Borisovich , Zakharov Robert Grigorievich
Published: March 2009

Specific features of the structural phase transitions of the first order were investigated in nanosized crystals with Jahn-Teller ions. As an example the phase transitions of martensite type with changes in symmetry from a cubic to a tetragonal one have been considered. The Kanamori model was used to take into account the size of nanocrystallites and the distribution of cations over non-equivalent crystallographic sublattices in such systems. It was shown the temperature and the latent heat of the transition decrease significantly for the nanoscaled grains. A possibility of multi-phase state for nanocrystalline materials was considered.
Some Basic Results and Techniques of Studying Anomalous Diffusion and Segregation in Metals: Relevance to New Nanofabrication Applications
Authors: Nechaev Yuriy S. , Öchsner Andreas
Published: March 2009

New possible nanotechnology applications of some original developments and results
of studying the regularities and micromechanisms (physics) of the hydrogen °uoride gas activa-
tor in°uence on oxidation of titanium, zirconium and zirconium-based alloys with niobium, and
also - on nitriding, boriding and carbiding a series of refractory metals (Ti, Zr, Nb, Mo, W, Ta)
are elaborated. The new possible nanotechnology applications of the techniques and physics of
creating a compound-like nanosegregation or the liquid-like nanosegregation at grain bound-
aries in nanostructured metals, i.e. creating of speci¯c cellular type natural nanocomposites,
are considered as well.
The Effect of Mg2+ and Tara Gum Concentrations on the Rheological Properties of WPI Solutions
Authors: Vázquez da Silva M. , Delgado João M.P.Q.
Published: March 2009

Cold-set gels of whey protein isolate (WPI) and of WPI plus polysaccharide were produced. The cold gelation was induced through the addition of magnesium chloride whose cation is an alternative to the most common cations used in this kind of gelation. The polysaccharide used was tara gum (TG) which is a galactomannan with many applications in the food industry.
The viscoelastic behaviour of the WPI, TG and WPI+TG samples was analysed: Newtonian behaviour was observed for WPI while TG and WPI+TG displayed typical rheological behaviours of thickened fluids that can be described through the Cross and Carreau models, for which the parameters are presented.
Current-Voltage Measurements on Indium Phosphide Schottky Diodes
Authors: Sequeira César A.C. , Santos Diogo M.F.
Published: March 2009

In this paper, current-voltage (i-Vg) results from different kinds of n-type InP Schottky diodes are reported. The diodes were fabricated on an unintentionally doped n-type (100) indium phosphide substrate, and the i-Vg characteristics were measured in the temperature range 100 300 K. For the ideality factor, n always exhibited a small (1) but continuous increase with the voltage. At higher forward voltage, slightly higher values of n were due to series resistance effect; in other words, the interface state density always remained small. However, it was possible to obtain some information in the case of discrete interface traps. It was shown that i-Vg measurements can be used as a fast method to determine the densities of the interface states when they equilibrate with the semiconductor.
A Porous Medium Materiel Used In Solar Energy Conversion
Authors: Benzaoui Ahmed , El Gharbi Najla
Published: March 2009

Intense research on development of ozone and global warming protection heat pump machine technology is observed, because of the international environment protection. In arid areas, electricity network is not often available or it is at high price while the sun is shining and the cooling demand is important during almost the year. Absorption refrigeration has been intensively investigated over the world, during the last twenty years.
This report is concerned by the solar energy conversion and use in an absorption cooling process where a specific porous medium is used to improve the efficiency. This process is the best appropriate solution to refrigeration and air conditioning problems in the desert areas and other remote countries where electricity power network is not available.
The simulation of absorbing/desorbing chemical reaction in a solar cooling system, working according to absorption principle has given some results allowing to confirm the efficiency improve, the economical and technical feasibility and to avoid difficulties.
Grape Seeds Dehydration under Forced Convection Conditions
Authors: Clemente G. , Sanjuán N. , Bon J. , Peña R. , García-Pérez J.V.
Published: March 2009

Grape pomace is the main by-product from the wine industry. It is principally made up of grape skin and seeds. Drying this by-product is the first step for the later extraction of components with high added value like oil or antioxidants. Due to the different characteristics of the components, the study of the drying kinetics of grape pomace must be addressed taking its components into account one by one. For that purpose, grape seeds from the Spanish wine industry were dehydrated in a convective laboratory dryer at 70 °C and at 1, 2 and 3 m/s until a weight loss of 40% was reached. Drying kinetics was determined in triplicate. Modelling was carried out by means of a diffusion model without considering shrinkage and external resistance. Grape seeds were assumed to be spherical. For all the fits, the explained variance was higher than 96.9 % and the mean relative modulus was lower than 1.7 %. Between 1 and 2 m/s, effective diffusivity increased in line with air velocity, although the values of effective diffusivity calculated for 2 and 3 m/s were similar. It seems to indicate that for the experimental conditions under study, the external resistance is not negligible at 1 and 2 m/s and for higher air velocities the internal resistance to mass transfer controls the drying process. These results coincide with those found by other authors when studying different food products.
Analysis of the Flow at the Interface of a Porous Media
Authors: Hayashi Thamy C. , Malico Isabel , Pereira J.F.C.
Published: March 2009

The influence of inserting ceramic foam in a pipe with a 1:4 sudden expansion was numerical investigated. The foam, with a thickness to diameter ratio of 0.60, was positioned at different distances from the sudden pipe expansion wall. Three different porosities were analyzed (10, 20 and 60 pores per inch) for pore Reynolds numbers in the range of 20-400, corresponding to pipe Reynolds numbers of 2400 to 22000 in the pipe section upstream the sudden expansion. Predictions of the sudden pipe expansion cavity assuming laminar flow within the foam yield the penetration of the separated flow region into the foam. Considering turbulent flow in the porous foam and the model of Pedras and Lemos [14] prevents this penetration. The numerical and physical models used could not reproduce completely the foam influence on the separated turbulent flow region between the sudden pipe expansion and the foam inlet.
Desorption Kinetics of Hydrogen in Mg2NiH4 Hydride and in Hydrogeneated Eutectic (Mg/Mg2Ni)Hx
Authors: Cermak Jiri , Kral Lubomir
Published: March 2009

Mg-Ni alloys are perspective hydrogen-storage materials. In the present work, kinetics of hydrogen desorption was studied in Mg2NiH4 hydride and in hydrogenated eutectic (Mg/Mg2Ni)Hx. Time dependence of desorbed hydrogen was measured in temperature interval 552 –723 K and hydrogen diffusion coefficients were evaluated from obtained desorption curves. Results were interpreted in relation to phase composition investigated parallel by XRD. It was found that microtwinned low-temperature phase LT2 slows-down considerably the hydrogen desorption rate.
The Influence of Deep Cryogenic Treatment on Precipitation Phenomena during Tempering and Ageing
Authors: Wierszyłłowski Ignacy , Niemczyk Waldemar
Published: March 2009

The paper presents results of comparative studies of tempering processes of quenched and conventionally treated tool steel vs. the same steel quenched and cryo-treated. Also ageing processes of Al-4.7%Cu alloy after conventional and cryo-treatments are analyzed and the results presented. It has been observed that in both cases cryogenic treatment has an effect on the development of the tempering and ageing processes. The mechanisms of the influence are different in each case. In the cryo-treated steel, the tempering processes already begin in the process of reaching ambient temperature from 196°C and accelerate the increase in hardness because of tempering. In conventionally treated Al-Cu alloy the processes of dissolving precipitates and the resulting decrease in hardness occur earlier than in the cryo-treated alloy. Reazons of such changes have been analyzed.