bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Ag Addition on Superconductivity and Microstructure of DyBa2Cu3O7-δ-Ag Composite
Authors: Musa Baktiar , Yahya Ahmad K. , Salleh Faizah Md. , Abd-Shukor R.
Published: March 2009

This paper reports on the effects of Ag addition on physical properties of high
temperature superconductors DyBa2Cu3O7-δ (Dy123). A series of the Dy123 - Agx composite was
prepared by solid state reaction method with varying amount of metallic silver (x = 0 – 0.3).
Resistance versus temperature measurement was done using the four-point-probe method in the
temperature range of 79 K to 300 K. Pure DyBa2Cu3O7-δ was found to superconduct with Tc onset of
91 K and Tc zero of 78 K. Addition of Ag at x = 0.05 caused both Tc onset and Tc zero to increase to 93
K and 84 K, respectively. However, Tc onset and Tc zero dropped for higher silver contents. We found
that the optimum silver content in DyBa2Cu3O7-δ for best superconducting behavior and hardness is
between x = 0.05 and 0.10. Microstructure analysis using SEM and EDAX showed that most of the
silver is uniformly distributed along the grain boundaries filling the pores and hence increasing the
hardness of the samples.
Mechanism of a Solid-State Formation of La1-xSrxMnO3+δ (0 < x < 0.5) and Magnetic Characterization thereof
Authors: Uskoković V. , Drofenik Miha
Published: March 2009

Investigations of the influence of synthesis procedures and LaSr-manganite
stoichiometries on the Curie point and other magnetic characteristics of the material, being the topic
of this work, are attractive since they present a necessary primal step in the intended development
of nano-magnetic drug carriers based on these materials. In the course of such an investigation,
differences in the mechanisms of the formation of desired manganite compounds by following a
classical solid-state preparation method, depending on various stoichiometries used, were noticed,
with the reaction pathways thereof outlined onward.
Ion Beam Assisted Deposition of TiN Thin Films on Si Substrate
Authors: Milinović V. , Milosavljević M. , Popović M. , Novaković M. , Peruško D. , Radović I. , Bibić N.
Published: March 2009

In this paper we present a study of the formation of TiN thin films during the IBAD
process. We have analyzed the effects of process parameters such as Ar+ ion energy, ion incident
angle, Ti evaporation rates and partial pressure of N2 on preferred orientation and resistivity of TiN
layers. TiN thin films were grown by evaporation of Ti in the presence of N2 and simultaneously
bombarded with Ar+ ions. Base pressure in the IBAD chamber was 1⋅10-6 mbar. The partial pressure
of Ar during deposition was (3.1 – 6.6)⋅10-6 mbar and partial pressure of N2 was 6.0⋅10-6 -
1.1⋅10-5 mbar. The substrates used were Si (100) wafers. TiN thin layers were deposited to a
thickness of 85 – 360 nm at deposition rates of Ti from 0.05 to 0.25nm/s. Argon ion energy was
varied from 1.5 to 2.0 keV and the angle of ion beam incidence from 0 to 30o. All samples were
analyzed by Rutherford backscattering spectrometry (RBS). The changes in concentration profiles
of titanium, nitrogen and silicon were determined with 900 keV He++ ion beam. The RBS spectra
were analyzed with the demo version of WiNDF code. We have also used X-ray diffraction (XRD)
for phase identification. The resistivity of samples was measured with four-point probe method. The
results clearly show that TiN thin layer grows with (111) and (200) preferred orientation, depending
on the IBAD deposition parameters. Consequently, the formation of TiN thin layers with wellcontrolled
crystalline orientation occurs. Also, it was found that the variations in TiN film resistivity
could be mainly attributed to the ion beam induced damage during the IBAD process.
Surface Modification of Titanium by High Intensity Ultra-Short Nd:YAG Laser
Authors: Trtica M. , Gaković B. , Maravić D. , Batani D. , Desai T. , Redaelli R.
Published: March 2009

The effects of an Nd:YAG laser interaction with titanium target using laser radiation at
wavelengths 1.064 or 0.532 μm (40 picoseconds pulse duration) were studied. Modification of
target surfaces at laser energy densities of 2.4 and 10.3 J/cm2 (λ1
laser= 1.064 μm) and 1.1 J/cm2
(λ2
laser= 0.532 μm) are reported in this article. Qualitatively, the titanium surface modification can
be summarized as follows: (i) ablation of the titanium surface in the central zone of the irradiated
area for both laser wavelengths; (ii) appearance of a hydrodynamic feature like resolidified droplets
of the material (λ1
laser= 1.064 μm), as well as formation of the wave-like microstructures (λ2
laser=
0.532 μm); and (iii) appearance of plasma, in front of the target, with both laser wavelengths.
Electrochemical Behaviour of a Composite Rh/TiO2 Layer Formed Potentiodynamically on Titanium Surface
Authors: Mentus S. , Krstić Ivan , Tešić Ž. , Montone Amelia
Published: March 2009

Potentiodynamic polarization of a mechanically polished titanium electrode in a diluted solution of Rhodium(III) chloride in 0.1 M perchloric acid was performed, resulting in simultaneous formation of both Rh and TiO2 films. The morphology of obtained Rh/TiO2 composite film followed the morphology of titanium support, as evidenced by SEM technique. This composite surface was examined by cyclic voltammetry in both acidic and alkaline solutions, in the potential region of both hydrogen and oxygen underpotential deposition. The charge related to hydrogen underpotential deposition corresponded to a surface roughness of 43. As a consequence of high surface roughness, the diffusion current of oxygen reduction in an oxygen saturated 0.1 M NaOH solution, measured by voltammetry on rotating disc electrode, was found to be comparable to the current of hydrogen underpotential deposition.
Photoacoustic and Optical Properties of Zinc-Stannate Thin Films
Authors: Ivetić Tamara , Nikolić Maria V. , Young David L. , Vasiljević-Radović Dana , Urošević Dragan
Published: March 2009

Thin films of single-phase zinc-stannate (Zn2SnO4) were grown by rf magnetron sputtering onto glass substrates. Transmission in the visible range was measured allowing determination of the energy gap and thickness of analyzed thin film samples using interference fringes. The photoacoustic phase and amplitude spectra of all samples were measured as a function of the laser beam modulating frequency using a transmission detection configuration. Fitting of experimental data enabled calculation of thermal diffusivity, the coefficient of minority carrier diffusion, their mobility and lifetime.
Syntheses of Ferrite Nanoparticles Using Ultrasound Irradiation
Authors: Drofenik Miha , Kristl M. , Makovec Darko , Košak Aljoša
Published: March 2009

Sonochemically assisted co-precipitation has been used to prepare nanosized manganesezinc-
ferrite powder. A suspension of constituent hydroxides was ultrasonically irradiated for various
times with high-intensity ultrasound radiation (20 kHz, 750 W) using a direct-immersion titanium
horn. The average grain size and magnetization of the synthesized MnZn-ferrite nanoparticles
gradually increases with the time of ultrasonic irradiation.
Films as Characteristic Consolidated Nanostructured Materials
Authors: Andrievski R.A.
Published: March 2009

Nanostructured films are considered as a characteristic (distinctive) type of consolidated nanostructured materials (NMs). Their benefits as compared to other types of NMs are described in detail. Some new interesting results related to mechanical and physical properties of nanostructured films based on high-melting point compounds (nitrides, borides and carbides), metals, and oxides are discussed. Data on film hardness, type of deformation, effect of additional magnetic field at deposition of films, properties of twins, conductivity, coercivity, and the Hall coefficient are reported and commented.
A Japanese Perspective on the Use of Aluminium Alloys in the Automotive Sector
Authors: Suzuki Masami
Published: March 2009

Recently, average automobile weight has shown the tendency of increasing, due, in part, to
the the addition of equipment to improve convenience, comfort and safety. At the same time, to help
reduce CO2 emissions in the global environment, vast improvment to automobile fuel consumtion is
needed. More and more, vehicle weight reduction is being pursued in order to improve fuel economy,
but always with a consideration not to sacrifice performance. A design that includes aluminum can
be very effective for reducing vehicle weight, however, it is also true that with aluminum there is a
concern for increased cost. The use of aluminium alloys in Japan for vehicles started with castings
for engines and transmissions. It continues to rival steel for applications in body and chassis
components, especially now with the development of higher tensile strength steels. For the expanded
use of aluminum, cost effective strategies, such as that of complex part integration, are necessary, to
say nothing of the need for a reduction in raw material cost.
Laser and Hybrid Laser-MIG Welding of 6.35 and 12.7mm Thick Aluminium Aerospace Alloy
Authors: Allen C.M. , Verhaeghe G. , Hilton P.A. , Heason Chris P. , Prangnell Philip B.
Published: March 2009

Fusion welding of 7xxx aluminium alloy plates has been investigated for aerospace applications using autogenous laser welding and hybrid laser-MIG welding. Nd:YAG and Yb-fibre lasers have been used, with two different focussed spot sizes in each case. Autogenous and hybrid welding of 12.7mm thick plate using the Yb-fibre laser with a 0.6mm diameter spot was selected for further development, on the basis of penetration and weld quality achieved. These welds were acceptable to the highest quality class B (stringent) of BS EN ISO 13919-2:2001, with a porosity of only 0.3% of the cross-sectional area of the weld, and close to class A of AWS D17.1. Transverse proof strengths of ~60% of parent material were achieved. Development of hybrid welding is ongoing with novel fillers to refine weld metal grain structure and improve weld properties.
Synthesis of Aluminium Based Bulk Materials from Micro and Nano Particles Using Back Pressure Equal Channel Angular Consolidation
Authors: Wu Xiao Lin , Xia Kenong
Published: March 2009

An innovative process for synthesising bulk materials using particles has been developed. The process is termed back pressure equal channel angular consolidation (BP-ECAC). Aluminium based materials were successfully consolidated into bulk materials using particles from nano to micro scales. BP-ECAC allowed the particles to be used directly without pre-compacting and casing and the processing temperatures to be significantly lower than those used in conventional sintering. Fully dense bulk samples were obtained instantaneously as the particles were forced to pass the shearing zone under pressure. Nanostructured materials were obtained from the nanometre-sized Al particles. Significant strengthening of the consolidated materials were observed. The new process is promising in producing porosity free, large volume materials with special compositions and structures.
Comparing the Influence of Mn and Fe Content on the Fracture of a AA6XXX Series Alloy in Different Aged States
Authors: Corbin S.F. , Ansah-Sam E. , Lloyd David J.
Published: March 2009

The objective of this study was to investigate and compare the influence of Mn and Fe
additions on the fracture behaviour of AA6000 series alloys in under, peak and overaged conditions.
Testing was completed under uniaxial tension and the microstructures of the alloys were observed
using optical and Transmission Electron Microscopy. Alloys with very low levels of both Mn and
Fe underwent a transition from transgranular to intergranular fracture and a reduction in strain-tofracture
when heat treated from the under aged (UA) to peak aged (PA) condition. Increasing Mn
and Fe content prevents this transition in fracture mode such that the stain-to-fracture is similar in
the UA and PA states. Despite the change in fracture mode, when comparing the strain-to-fracture
for a given ageing condition, increasing Fe systematically reduces the strain-to-fracture.
Conversely, increases in Mn systematically increase the strain-to-fracture for a given ageing
condition.
Early Stage Hardening in AlCuMg Alloy Studied by 63Cu Nuclear Magnetic Resonance and Positron Annihilation
Authors: Bastow Timothy J. , Hill Anita J.
Published: March 2009

Nuclear magnetic resonance (NMR) is shown to be a sensitive metallurgical
characterization technique for metastable phase development during early stage aging of the high
purity experimental alloy Al(1.05Cu 1.7Mg) (at.%). It is shown, using 63Cu NMR and positron
annihilation lifetime spectroscopy (PALS), how room temperature structural evolution proceeds in
Al(1.05Cu 1.7Mg) prepared in the form of supersaturated solid solution. The combination of NMR
and PALS allows identification of solute aggregate chemistry and defect kinetics during natural
aging. Guinier-Preston-Bagaryatsky (GPB) zone formation is detected by NMR within 0.5 h of
quench, and the percentage of Cu atoms in GPB zones increases to ~80% within 50 h at room
temperature, with the residual 20% of Cu atoms remaining in solid solution. The formation of GPB
zones corresponds with the Vickers hardness, in fact the hardness is shown to directly depend on the
amount of total Cu partitioned to GPB zones. The vacancy kinetics, as measured by PALS, show an
exponential decay in time following the quench with the majority of decay complete within 50 h
supporting the notion that early stage hardening by GPB zone formation is controlled by defect
concentration and availability.
Understanding T-Ingot Horizontal DC Casting Using Process Modelling
Authors: Larouche André , Lane Malcom , DiCiano Massimo , Maijer Daan M. , CockCroft Steve , Thiffault Roger
Published: March 2009

Horizontal continuous casting process has been successfully implemented in Alcan for
the production of T-ingots of primary aluminium and foundry alloys. Ability to achieve increased
productivity targets and reduce production costs relies on a fundamental understanding of key
process characteristics and operating parameters. Thanks to the long-standing experience in vertical
DC Casting, numerical modelling appeared as a powerful approach to understand phenomena
related to metal flow, solidification and ultimately defect formation.
As part of a collaborative R&D program, a global model of horizontal casting process, integrating
specialized sub-models on critical aspects of the process such as meniscus dynamics, is being
developed. Experimental characterization of primary and secondary cooling is performed in parallel
with modelling work to provide the information necessary to properly characterize mould heat
transfer. This paper will present the development of a 3D process model of T-ingot casting along
with its application to solve specific process challenges that have emerged during the first years of
production in the plant.
In Situ SEM-EBSP Observations of Recrystallization Texture Formation in Al-3mass%Mg Alloy
Authors: Kajihara Katsura , Matsumoto Kazuhide , Matsumoto Katsushi
Published: March 2009

This study presents in situ observations of recrystallization texture formation in
Al-3mass%Mg using SEM concurrent with electron back scattering pattern (EBSP) with hot stage. In
the present discussion, the emphasis is on the characteristics of the preferred growth or the shrinkage
of Cube and other oriented grains. The in-situ observations of recrystallization demonstrate clearly
that the nucleation, growth and shrinkage of recrystallized grains occur simultaneously in each
orientation in each region. The overall development of recrystallization texture depends on the
balance of nucleation/growth and shrinkage/disappearance of each orientation during
recrystallization. The preferential growth is determined by the grain boundary mobility between
recrystallized grains or the clusters composed of several similar oriented grains, i.e. Cube clusters or S
clusters, and neighboring deformed matrix, and the competitive growth with the surrounding grains.
On the other hand, the isolated oriented grain and the strain-stored grains tend to shrink and disappear
during recrystallization and grain growth.
Precipitation and Recrystallization in an Al-Mg-Sc Alloy
Authors: Roumina R. , Sinclair Chad W. , Fazeli F.
Published: March 2009

The addition of scandium severely retards the recrystallization of Al-Sc alloys when it is
present in the form of fine Al3Sc precipitates. Though many studies have focused on the role of
Al3Sc in the deformation and recrystallization of pre-aged or hot deformed Al-Sc alloys, recent
studies on the annealing response of solutionized and cold rolled material have shown various
possibilities for microstructural stability depending on the relative kinetics of precipitation and
recrystallization. In this study, the microstructural evolution of solutionized and cold rolled Al-
2.9wt%Mg-0.16wt%Sc has been followed in order to evaluate the role of imposed strain and
annealing temperature on the recrystallization kinetics.
Light Alloy Castings for Automotive Applications: The Case of Al vs. Mg
Authors: Cáceres Carlos H.
Published: March 2009

The economical and environmental effects of mass reduction through Al and Mg primary
alloys substitutions for cast iron and steel in automotive components are discussed using M.F.
Ashby’s penalty functions method. The viability of Mg alloy substitutions for existing Al alloy cast
components is also considered. The cost analysis shows that direct, equal-volume, Al alloy
substitutions for cast iron and steel are the most feasible in terms of the CAFE liability, followed by
substitutions involving flat panels of prescribed stiffness. When the creation of CO2 associated to
the production of Al and Mg is considered, the potential gasoline savings over the lifespan of the
car compensate for the intrinsic environmental burden of Al in all applications, while electrolytic
Mg substitutions for cast iron and steel are feasible for equal volume and panels only. Magnesium
produced by the Pidgeon thermal process appears to be too primary energy intensive to be
competitive in structural applications. Magnesium substitutions for existing Al alloy beams and
panels are generally unviable. The current higher recycling efficiency of Al casting alloys confers
Al a significant advantage over Mg alloys.
Crystal Analysis of Nonequilibrium δnon-Phase in Al-Li-Mg Alloys
Authors: Alekseev A.A. , Lukina E.A. , Zaytsev D.V. , Fridlyander I.N.
Published: March 2009

The nonequilibrium δnon-phase was originally investigated in the work[1] when studying
the ageing processes of the 1424 alloy ( Al-Li-Mg-system). As shown in the work[2] this phase
may also be formed during the cooling from the temperature of SSHT. The δnon-phase precipitates
are also present in 1420 alloy of the same system[3].
The basic structure investigations were carried out on the 1424 alloy sheets aged in accordance
with the regime: 125°C, 32 hrs. The investigations were performed by TEM using the JEOL JEM
200CX microscope.
The diffraction patterns from the δnon-phase on the crystallographic axes of zones close to
<110>, <111>, <112> were obtained. It can be seen that the regular reflex networks appeared after
the deviation from axes of zones by 3-4˚. It was established that the lattice parameters of δnon-phase
and its orientation relation with the matrix can be approximately described by the following way:
aδnon≈ aα/2[112] b δnon ≈a α/2[110] cδnon≈ a α [111]
where aα- the period of the FCC- lattice of solid solution.
The model of the crystallographic structure of the δnon-phase precipitates is proposed. On the
basis of this model the mechanism of the δnon-phase formation is discussed. The late ageing stages
are analyzed and it was shown that the δnon-phase particles are the nuclei for S1(Al2LiMg)- phase.
A Multi-Mechanistic Model for Precipitation Strengthening in Al-Cu-Mg Alloys during Non-Isothermal Heat Treatments
Authors: Khan I.N. , Starink Marco J.
Published: March 2009

A multi-mechanistic model for microstructure development and strengthening during nonisothermal
treatment of precipitation strengthened Al-Cu-Mg based alloys is derived. The formation
kinetics of the precipitates is modelled using the Kampmann and Wagner numerical model that
accounts for complete transformation from the nucleation to the coarsening stages. The increase in
critical resolved shear strength of the grains due to the precipitates is based on two mechanisms i.e.
the modulus strengthening mechanism for the shearable Cu:Mg co-clusters and the Orowan
strengthening mechanism for the non-shearable S phase precipitates. The contributions due to solute
and dislocation strengthening are also included in the strength calculations. The model is verified by
comparing the predicted results with differential scanning calorimetery and hardness data on 2024
aluminium alloys. The microstructural development and strength/hardness predictions of the model
are in reasonable agreement with the experimental data and the differences are discussed in terms of
requirements for further model development.
Cluster Dynamics Modelling of the Precipitation Kinetics in Al(ZrSc) Alloys
Authors: Guyot Pierre , Sigli Christophe
Published: March 2009

The precipitation kinetics path in multi-component alloys may involve a competition
between atomic mobilities and precipitates thermodynamic stability. Cluster dynamics modelling
(CDM) is a simulation method that allows to describe this competition without introducing any
heuristic assumptions as, for example, in the classical theory of nucleation. CDM consists in solving
numerically, for each time increment, the master equations expressing the balance of solute
exchanges (absorption and emission) between clusters/precipitates. A key issue is the energetics of
the nano-clusters in the nucleation range. The computation of the precipitate size distribution
function allows the complete description of the precipitates kinetic evolution, in chemical
composition and in size. The method is applied to the precipitation of the Al3(Zr,Sc) L12 phase in Al
solid solutions. The model predicts fairly well in the precipitation path some observed coupling
effects between the two solutes, particularly during the nucleation stage.
Microstructural Evolution of a New Aerospace 7XXX Alloy during Retrogression and Re-Ageing Treatment
Authors: Tanaka M. , Hénon C. , Warner Timothy
Published: March 2009

RRA treatment was applied to a high-Zn, 7XXX alloy under development for aerospace applications. Microstructure of the alloy is studied at different stages of the 3-step ageing process, by Transmission Electron Microscopy, in order to understand the corresponding evolution of mechanical and corrosion properties. The Compression Yield Strength at the end of the high temperature step was found higher than at the end of the 1st step, contrary to the conventional RRA treatment. After re-ageing, the final CYS turned out significantly higher than at the T6 temper of the alloy, while the material remained sensitive to exfoliation corrosion.
Effect of Minor Sb Additions on SDAS, Age Hardening and Mechanical Properties of A356 Aluminium Alloy Casting
Authors: Boontein Supparerk , Prukkanon Wattanachai , Puparatanapong Kongkiat , Kajornchaiyakul Julathep , Limmaneevichitr Chaowalit
Published: March 2009

A356 is the aluminum casting grade which has compositions that combines outstanding
casting characteristics with excellent properties after heat treatment. Mechanical properties of A356
can be improved by reducing of secondary dendrite arm spacing (SDAS), precipitation hardening,
and the interaction effect of both. It is generally accepted that dendrite arm spacing and fine
distribution microstructure are related to each other and they also affect the precipitation hardening
in a way that smaller SDAS results in shorter time required to obtain a satisfactory degree of
solution of the undissolved or precipitated soluble phase constituents and to achieve good
homogeneity. Minor addition of Sb was successfully used in reducing the SDAS in previous work.
However, the effect of Sb addition on age hardening has not been investigated, especially in a high
cooling rate condition. In this research, effects of minor addition of Sb on SDAS, age hardening and
mechanical properties; i.e. hardness and tensile properties, are reported. It was found that Sb
addition did not clearly affect SDAS at the high cooling rate, i.e. as in permanent mold casting
process. Moreover, we found that the addition of Sb into A356 also lowered mechanical properties.
Significance of Low Copper Content on Grain Boundary Nanostructure and Intergranular Corrosion of AlMgSi(Cu) Model Alloys
Authors: Larsen Magnus Hurlen , Walmsley John Charles , Lunder Otto , Nisancioglu Kemal
Published: March 2009

Intergranular corrosion (IGC) of model alloys in the 6000-series, with and without 0.2 wt% Cu, was studied using an accelerated corrosion test (BS ISO 11846 B), FE-SEM and FE-TEM. Low Cu alloys (0.02wt%) did not exhibit IGC even though they contained excess Si. The high-Cu, naturally aged material (T4) was susceptible to severe superficial etching. In the underaged state (below peak strength), the Cu-containing material was highly susceptible to IGC. Materials aged to peak strength (T6) or overaged were only slightly susceptible to IGC, with localized, shallow attacks. FE-TEM investigation of the underaged material revealed scattered, small AlMgSiCu-type precipitates, as well as a Cu-enriched film along the grain boundaries. The overaged material showed more extensive, coarse grain boundary precipitation. However, the Cu-enriched film was still present at localized sites. The reduced susceptibility to IGC upon artificial ageing was attributed to breaking of the continuity of the grain boundary film. The possible role of matrix precipitation is also discussed.
The Work Hardening of Single Phase and Multi-Phase Aluminium Alloys
Authors: Embury J. David , Poole Warren J. , Lloyd David J.
Published: March 2009

The process of work hardening in aluminum alloys is important from the viewpoint of
formability and the prediction of the properties of highly deformed products. However the
complexity of the strengthening mechanisms in these materials means that one must carefully
consider the interaction of dislocations with the detailed elements of the microstructure and the
related influence of the elements on dislocation accumulation and dynamic recovery.
In addition, it is necessary to consider the influence of the work hardening process at various levels
of plastic strain. This permits the possibility of designing microstructure for tailored plastic response,
e.g. not simply designed for yield strength but also considering uniform elongation, spring-back,
ductility etc. This presentation will explore the concept of identifying the various interactions which
govern the evolution of the work hardening and their possible role in alloy design.
Effect of Copper Content on the Bendability of Al-Mg-Si Alloy Sheet
Authors: Asano M. , Minoda Tadashi , Ozeki Y. , Yoshida Hideo
Published: March 2009

The effects of the copper content on the bendability of Al-Mg-Si alloy T4 sheets were investigated. The Al-Mg-Si alloys with less than 0.01mass%Cu, 0.4mass%Cu and 0.8mass%Cu were prepared, and the time of solution heat treatment was changed to obtain different dispersion conditions of the second phase particles and to obtain different shear band formation conditions by bending. For the samples with less than 0.01mass%Cu and 0.4mass%Cu, no cracks were observed during the bending. For the sample with 0.8mass%Cu, the maximum depth of the crack by bending increased with the time of solution heat treatment up to 75 seconds, and then decreased over 75 seconds. The second phase particles decreased by increasing the solution heat treatment time, while the formation of shear bands by bending increased by increasing the solution heat treatment time and the copper content. The cause of the occurrence and the propagation of cracks by bending are considered to be the combined effect of the shear band formation across some grains and the micro-voids formed around the second phase particles. Improving of the bendability requires a decrease in the size and number of the second phase particles and/or reduced shear band formation during the bending.
Hot Corrosion and Steam Oxidation Properties of New Heat Resistant Steels for Ultra Super Critical Boilers
Authors: Fukuda Yuji , Shimizu Masaru
Published: March 2009

Achieving higher plant efficiency in thermal power plants is one of the major global challenges from the viewpoint of reducing carbon dioxide emission levels, particularly in coal-fired boilers, irrespective of the type of coal being burned. In recent times, it has been possible to increase the steam temperature in coal fired ultra supercritical (USC) plants without too much of a cost impact. The temperature has already been increased to 600 for main steam and 610 for reheat steam. The main enabling technology is the development of stronger high temperature materials such as newly developed high Cr ferritic steels and austenitic steels, capable of operating under high stresses at increasing high temperatures. Other key demands for those materials are hot corrosion resistance such as coal ash corrosion in superheater and reheater tubes and sulfidation of waterwall tubes, and steam oxidation resistance. This paper will mainly present the hot corrosion and steam oxidation properties of newly developed high strength heat resistant steels for their application to USC boilers and long-term experience in an actual plant.
Wet Oxidation: A Promising Way for Fabrication of Zinc Oxide Nanostructures
Authors: Gao Wei , Li Zheng Wei
Published: March 2009

A two-step deposition-oxidation method was successfully developed to fabricate zinc oxide thin films and nanostructures. Morphological observations clearly showed that a controllable growth of dense/porous oxide films, nanowhiskers, nanowires, and nanobelts could be obtained by controlling the deposition and oxidation conditions. Photoluminescence properties of the ZnO films were also studied. A strong and predominant ultra-violet near-band-edge emission could be observed on most of the samples, while a green or red color emission accompanying with a largely suppressed ultra-violet emission could be realized on the samples with different processing conditions. The results therefore indicated that ZnO films and structures with desirable microstructural and optical properties could be obtained with this deposition-oxidation technique under controllable conditions.
Development of New Bond Coat System in Ni-Base Alloys
Authors: Sato Akihiro , Harada Hiroshi , Kawagishi Kyoko
Published: March 2009

Ni-base single crystal (SC) superalloys containing high concentrations of refractory elements are prone to generate a diffusion layer called Secondary Reaction Zone (SRZ) beneath their bond coating during exposure at high temperatures. SRZ causes a reduction of the load bearing cross section and is detrimental to the creep properties of thin-wall turbine airfoils. In this study, a new coating system – “EQ coating”, which is in thermodynamic equilibrium with the substrate, has been proposed and the formation behavior of SRZ beneath bond coat materials was investigated on the 5th generation Ni-base SC superalloy developed by NIMS. Diffusion couples of several alloys were made and were heat treated at 1100°C for 300 h, 1000 h. The concentration profiles were analyzed by EPMA. Also, cyclic oxidation tests were carried out at 1100°C in air.
The Effects of Steel Composition on the Oxidation Kinetics, Scale Structure, and Scale-Steel Interface Adherence of Low and Ultra-Low Carbon Steels
Authors: Chen Rex Y. , Yuen W.Y.Daniel
Published: March 2009

The oxidation behaviors of several commercial low and ultra low carbon
steels in air at 700-950°C were studied. Under isothermal oxidation conditions, the
oxidation kinetics, scale structure and scale-steel interface adherence were
significantly affected by the steel composition.
In Situ Study of Real Structure Effects on the Initial Oxidation of FeCrAl Alloys by Two-Dimensional High Temperature X-Ray Diffraction
Authors: Kodjamanova P. , Fietzek H. , Juez-Lorenzo Maria , Kolarik Vladislav , Hattendorf Heike
Published: March 2009

In order to contribute to a better understanding of the processes, which occur in the structure of FeCrAl alloys during oxidation, in situ – studies by two-dimensional high temperature X-ray diffraction (2D-XRD) using a global area detector and grazing incidence with a monocapillary have been performed. The 2D-XRD yields simultaneously with the identification of the oxides and their formation kinetics information about the grain size, grain shape, stresses, texture as well as grain movements during the oxidation process of both oxide and metal. Two commercial FeCrAl alloys with different reactive element additions were investigated in the temperature range of 850°C to 1100°C. In the range of 1100°C already in the first 5 min the alloy grains become coarse and appear as single spots along the lateral profile in the 2D-XRD pattern. Dynamic displacement of these spots along the 2θ – axis during the exposure indicates the formation of stresses, which differ from grain to grain. Initially, re-crystallisation and grain growth dominate and grains disappear and new grains appear. On further exposure the grains twist continuously with 1° to 3° per hour, depending on the alloy. The “dancing grain” effect of the alloy is probably related with growth stresses in the oxide scale and influenced by the bulging of the foil. Simultaneously, α-Al2O3 is detected from the first pattern after 5 min and shows an enhanced formation rate in the first 15 min of the oxidation. The α-Al2O3 grains are with 0.3 to 0.4 4m extremely fine and, a dense well adherent scale is observed even after 1 h.
Thermomechanical Modelling of a Steel Plate Impacted by a Shot and Experimental Validation
Authors: Rouquette Sébastien , Rouhaud Emmanuelle , Pron Hervé , François Manuel , Bissieux Christian , Roos Arjen
Published: March 2009

This work presents an experimental and numerical study of the thermo-mechanical problem of
a steel plate impacted by a shot. The temperature rise is estimated and its effect on the compressive
residual stress is analyzed. The simulations show that the value of the compressive residual stresses
at the surface of the plate is modified when thermo-mechanical effects are included in the model as
compared with simulation including hardening effects only. To validate this numerical study, an
experimental device has been developed to measure the temperature rise after the impact. The
experiment consists of the impact of a shot on a metallic plate. The temperature measurement is
performed by an infrared camera located on the side of the plate opposite to the impact. Comparison
between these experimental measurements and the numerical solution gives good agreement (to
within 5%).
Material Flow Curve Influence on Macroscopic Residual Stresses in the Workpiece Bottom in High-Pressure Sheet Metal Forming
Authors: Krux Rainer , Homberg Werner , Kleiner Matthias
Published: March 2009

The further development of innovative forming processes like sheet metal hydroforming
is only possible with the help of detailed knowledge about the workpiece properties and their
formation depending on the process strategy. Up to now, the knowledge about the formation of
macroscopic residual stresses in high-pressure sheet metal forming (HBU), regarding the influence
of the sheet material properties, is still insufficient. The characteristics of the specific forming
procedure HBU lead to specific stress and strain gradients in the sheet cross-section, and therefore
lead to a characteristic distribution of the induced macroscopic residual stresses, particularly in the
workpiece bottom zone. This paper decribes the investigations on the influence of the sheet material
flow curve on the macroscopic residual stress distribution in the workpiece bottom.
The New and Upgraded Neutron Instruments for Materials Science at HMI - Current Activities in Cooperation with Industry
Authors: Poeste T. , Wimpory Robert C. , Schneider Rainer
Published: March 2009

Recent progress in engineering includes the development of new materials and
innovations in their processing and treatments. Material technologies, like the study of metals,
alloys, ceramics and composites, especially non-destructive analyses of residual stresses profiles and
textures, have gained an increasing importance.
The dedicated residual stress diffractometers E3 and E7 at BENSC, HMI, Berlin are already
equipped with new two-dimensional position sensitive detectors. An upgrade of the monochromator
system is planned for 2006 which includes perfectly bent silicon crystals in order to optimise both
intensity and angular resolution yielding a large gain of the diffractometer efficiency for strain
measurements. A range of equipment for sample positioning is available, such as a closed Eulerian
cradle for samples with weights of up to 5 kg, a second cradle for heavy samples (up to 50 kg) with
the ability to tilt the samples up to 90° and a translation table carrying samples of up to 300 kg and
1000 mm in diameter. Gauge volumes can be adjusted by a new computer controlled variable slitsystem
in a range from 1x1x1 mm³ up to several mm³. In-situ residual stress analysis can be
performed within industrial components during mechanical or thermal loading (up to 2000 K).
Rapid data visualization as well as evaluation is performed by the specially designed software. The
powder diffraction pattern is calculated by summation over the scattering angle dependent Debye-
Scherrer lines on the two-dimensional 400*400 mm² planar area detector.
A large amount of beam time is exclusively used for industrial research. Among the components
that were investigated are crankshafts, impellers, pistons, cylinder heads, turbine blades and welds.
Both instruments are similarly designed, where E3 is set up for higher flux and therefore penetration
depths and E7 is designed for higher angular resolution.
The Influence of Aluminium Alloy Quench Sensitivity on the Magnitude of Heat Treatment Induced Residual Stress
Authors: Robinson Jeremy S. , Tanner David A.
Published: March 2009

To produce useful strengthening, precipitation hardenable aluminium alloys rely on rapid
quenching from the solution heat treatment temperature to suppress the formation of coarse
equilibrium second phases. An unavoidable consequence of the rapid quenching of thick sections is
the severe thermal gradients that quickly develop in the material. The attendant inhomogeneous
plastic flow can then result in the establishment of residual stresses. The surface and through
thickness residual stress magnitudes present in heat treated high strength aluminium alloy
components are frequently reported to exceed the uniaxial yield stress of small specimens of the
same alloy measured immediately after quenching. In thick section plate and forgings it is proposed
that these high residual stress magnitudes are a consequence of hardening precipitation that occurs
during quenching which allows for a greater elastic stress to be supported. To investigate this
theory, thick sections of the quench sensitive alloy 7175 and the less quench sensitive alloy 7010
were heat treated in such a way as to allow the internal hardness to be measured immediately, after
quenching. The rate of cooling was also monitored during quenching and these data were used in
conjunction with time temperature property data to predict the degree of precipitation and
subsequent loss of hardening potential in the fully heat treated condition. The magnitudes of the
residual stresses induced during quenching were determined using standard x-ray diffraction
techniques.
Residual Stress in Railway Rails by IP/cosα Method
Authors: Sasaki Toshihiko , Takahashi Shunichi , Iwfuchi Kengo , Satoh Yukio , Kanematsu Yoshikazu , Chiba Masanobu , Takago Shigeki
Published: March 2009

In this study, a new portable X-ray stress analyzer was designed and manufactured. The
purpose of its use is to evaluate the rolling contact fatigue damage in rails for establishing an
effective rail maintenance method. An image plate was used in this analyzer for detecting diffracted
X-ray beams. The cosα method was adopted for X-ray stress analysis from X-ray diffraction data. A
fundamental experiment was made first for examning the present measurement system. Residual
stresses in rails used in service for six years were also investigated in this study.
A Comparison of Strain Measurements on an Inertia Friction Weld Using the ENGIN-X and SALSA Neutron Strain Mapping Instruments
Authors: Karadge M. , Grant Benedict M.B. , Bruno Giovanni , Santisteban Javier R. , Withers Philip J. , Preuss Michael
Published: March 2009

In this study we present a direct comparison between residual strain measurements carried out on the same inertia friction weld using ENGIN-X at ISIS, UK and the new strain scanner SALSA at ILL, France. ENGIN-X is a time of flight (TOF) instrument, which receives neutrons from a neutron spallation source, while the SALSA Strain-Imager, a high resolution diffractometer, is based at a research reactor source with a continuous neutron flux and is operated with a constant wavelength. The purpose of this study was to demonstrate a confidence in crosscomparing future strain measurements to be performed at ENGIN-X and SALSA. Measurements were carried out on medium size inertia friction welded nickel superalloy test-piece, which show no significant crystallographic texture across the weld line. The results demonstrate that, even though residual stresses determined on SALSA only rely on a single peak analysis (in this case the (111) reflection), the results show excellent agreement with the measurements carried out on ENGIN-X, where strain is determined from multi-peak Rietveld analysis.
Residual Stress Analysis of Laser Welded Aluminium T-Joints Using Neutron Diffraction
Authors: Bayraktar Funda S. , Staron Peter , Koçak Mustafa , Schreyer Andreas
Published: March 2009

In this study the distribution and magnitude of residual stresses in a T-joint of aerospace
grade aluminium alloy weldment was determined using neutron diffraction. A 2 mm thick AA 6013
sheet (as clip) was laser beam welded to a 6 mm thick AA 6056 base plate (as skin) to resemble the
“short distance” welded clip-skin joints of an airframe. The total length of the weld was 120 mm
and it was welded using 3.3 kW Nd:YAG laser source and 12% Si containing wire from one side
only. No post weld heat treatment was applied after the welding. Start (run-in) and end (run-out)
locations of the T-joints are generally considered as high risk areas with respect to solidification
cracking and crack initiations under external loadings. It is of interest to investigate the weld
residual stress fields at these locations to develop optimum joint design. Therefore, strain
measurements have been performed not only in the middle of the weld seam but also at the run-in
and run-out locations of these short distance welds. Higher longitudinal tensile residual stresses are
detected at the run-out locations than the run-in locations. The measurements in the clip showed that
the clip has a longitudinal tensile stress peak away (about 8 mm) from the weld seam.
Ultrasonic Stress Measurement: Application to Preload Assessment on Already Tightened Bolts
Authors: Walaszek Henri , Bouteille Patrick
Published: March 2009

When a material is under mechanical load, the stresses modify the velocity of acoustic waves. This
consists in acoustoelastic effect. This property can be exploited for stress measurement in the
material itself when the stress concerns the surface of the material, or in the bulk material, as in
bolts.
The ultrasonic bolt tightening control allows knowledge of preload stress in screws. The accuracy
is much better than in the case of torque wrench. In fact, the use of this mechanical-based
measurement equipment leads to uncertainties due to random resistant torques, induced by
mechanical manufacturing tolerances. The ultrasonic measurement of the pre-load gives the
information about the tension inside of the bolt, independently of mechanical uncertainties. This
consists in an in-situ measurement. More, in some cases, the ultrasonic method allows knowledge
of the preload on bolts already tightened, without untightening. This method is called bi-wave
method, and has many connections with birefringent method.
Examples of application of the method are presented about the differential mode case, which is
largely known and industrialized, and in the case of bi-wave method, which lead to several on site
applications, performed by CETIM with a prototype equipment.
Development and Effects of Residual Stresses in Joints Produced by Electromagnetic Compression and its Implication on the Mechanical Properties
Authors: Barreiro Pablo , Schulze Volker , Löhe Detlef
Published: March 2009

Electromagnetic compression of tubular profiles with high electrical conductivity is an innovative
joining process for lightweight structures. The components are joint using pulsed magnetic fields
which apply radial pressures of up to 200 MPa to tubular work pieces causing a symmetric
reduction of the diameter with typical strain rates of about 104 sec-1. Since there is no contact
between components to be joined and the joining machine, any damage of component’s surface can
be avoided. The load, which the joint can transmit, is strongly dependent on the residual stresses in
the region of the joint. In the present article, the influence of charging energy, gap width before
joining and diameter on the development of the residual stresses is analysed using geometry
changes during splitting of the components. Besides, the contact zone between the components is
analysed and the pullout force of the joints is determined by tensile tests. This allows the evaluation
of correlations between joining process, state after joining and mechanical properties.
Plastic Heterogeneities Characterisation in 16MND5 RPV Steel by X-Ray Diffraction, Comparison with Finite-Element Approach
Authors: Mathieu Jean Philippe , Bouscaud Denis , Inal Karim , Berveiller Sophie , Diard Olivier
Published: March 2009

This paper reports experimental characterisation of stress heterogeneities in a French
RPV bainitic steel (16MND5) determined by X-Ray diffraction during in-situ tensile testing at low
temperature (until –150°C). Results are compared successfully to simulation results, obtained by
post-processing of Finite Elements computations of realistic 3D aggregates.
Measuring the Variation of Residual Stress with Depth: A Validation Exercise for Fine Incremental Hole Drilling
Authors: Fry A. Tony , Lord Jerry D.
Published: March 2009

Hole drilling along with X-Ray diffraction, is one of the most widely used techniques for
measuring residual stress, but the conventional approach is limited in the near surface detail that can
be resolved. Because of concerns regarding the levels of induced residual stress that might develop
during machining and surface treatment processes, there is significant interest in developing a
technique that can obtain near surface residual stress information by the application of fine
increment hole drilling. Through a cross comparison with X-ray diffraction and neutron diffraction
the procedure of fine incremental drilling has been validated, and the advantages of this technique
demonstrated.