bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Minimum Propagation Current of Bi-2223/Ag Superconducting Multifilament Tape
Authors: Bai Zhi Ming , Wu Chun Li , Yang Hai Liang , Wang Jin Xing
Published: March 2009

Minimum propagation current of Bi-2223/Ag superconducting multifilament tape was
studied in detail, including experimental investigation and numerical calculation using finite element
method (FEM). A set of experimental system has been established, quench propagation velocities
with various transport current have been measured and minimum propagation current has been
obtained in the condition of N2 gas cooling. The effect of parallel background magnetic field on
minimum propagation current has also been studied experimentally. In addition, minimum
propagation current at different operating temperature has been gained by the simulated calculation
using FEM.It has been found that the high temperature superconductor is stable if only transport
current is smaller than minimum propagation current of the time no matter what condition it is in.
Minimum propagation current can be considered as an important stability criterion of high
temperature superconductor.
Electrical Properties of a High-Tc Superconductor-Polymer Compersite
Authors: Chang Fang Gao , Fang Kun , Song Gui Lin
Published: March 2009

A superconductor-polymer composite of Bi1.8Pb0.4Sr2Ca2Cu3Oy and ethylene propylene
rubber (EPR) was prepared by conventional solid-state reaction method. The phase structure of the
composite was characterized by using x-ray diffraction technique. The resistivity of composite
samples annealed at different temperatures was measured between 40K and 300K. The results
indicate that the resistivity of the as-prepared composite increases with increasing EPR content and
shows essentially a semiconducting behavior above Tc. For fixed EPR content, the resistivity of
composite samples decreases with increasing annealing temperature. The composite begins to show
some signs of superconducting transition at an annealing temperature of 700 °C and zero resistance is
reached for samples sintered at 800°C. Thermal gravimetric analysis (TGA) on the composite
confirmed that 65% of the EPR content still present in the superconducting composite samples. SEM
was used to investigate the surface morphology of the composites. Preliminary results show that the
mechanical properties of the composite have been much improved compared with its parent
superconductor ceramics.
Influence of Processing Parameters on the Texture Formation in Powder Metallurgic Ni-5at.%W Substrate Tapes
Authors: Chen Shao Kai , Liu C.F. , Zhang Ping Xiang , Zhou Lian
Published: March 2009

Influence of cold rolling total thickness reduction, annealing temperature and annealing
time on the textures in powder metallurgic Ni-5at.%W substrate tapes have been quantitatively
investigated with the EBSD (Electron Back-Scattered Diffraction) technique. A “copper” type-like
texture consisting of {1 2 3}<6 3 –4>+{0 1 –1}<3 –1 –1>+{1 –1 2}<1 –1 –1> has been found in the
as-rolled tapes. This texture was much intensive in the tape at 99% thickness reduction than in the
tape at 87% thickness reduction. The 99% reduction tape showed a higher fraction and sharper cube
texture than the 87% reduction tape after annealing treatment. In addition, annealing at 1000°C was
much favourable for the cube texture formation than annealing at 950°C and resulted in a higher cube
texture fraction.
Influence of Mg and B Stoichiometry on the Formation Behavior of MgB2 Phase
Authors: Yan S.C. , Yan G. , Lu Ya Feng , Feng Y. , Zhou Lian
Published: March 2009

Bulk samples with the stoichiometry of Mg:B=1:2 and 1:4 were prepared by solid state
reaction method. The microstructure and constituent of the samples were investigated by using the
scanning electron microscope (SEM) and the x-ray diffraction (XRD). XRD results showed that the
MgB2 phase was first formed in all the samples with different stoichiometry of Mg and B, which
indicated that the MgB2 was the most thermodynamically stable phase in the Mg-B binary system. For
the samples of Mg:B=1:2, the MgB2 single phase was formed very well when these samples were
sintered at 650°C~700°C. For the samples with later added Mg reaching to the stoichiometry of
Mg:B=1:2, a longer reaction time or higher reaction temperature was required for the formation of the
MgB2 single phase. The SEM results showed that the samples with later added Mg had dense
microstructures, suggesting that the later addition of Mg could reduce the porosity of the sample. A
small increase of the superconducting transition temperature, Tc, in the Mg addition sample resulted
from the dense microstructures.
Effect of Thickness on Properties of MgB2 Thin Films
Authors: Zhuang Cheng Gang , Chen Chin Ping , Ding Li Li , Chen Li Ping , Zhang Kai Cheng , Li Fen , Feng Qing Rong , Gan Zi Zhao
Published: March 2009

Superconducting MgB2 films have been fabricated on sapphire substrate by the method of
hybrid physical-chemical vapor deposition (HPCVD). The film thickness ranges from 75 nm to 3 μm.
The investigation on the physical properties, such as the transition temperature, TC, the transition
width, T, and the critical current density, JC, has indicated that the optimum film thickness is about 1
μm. At this thickness, Tc(onset) = 40.3 K and 0Tc = 0.15 K. At T = 5 K without external field, JC has
been estimated as 5.6×105 A/cm2according to the Bean model. The film quality begins to degrade as
the thickness exceeds 1 μm. This work has demonstrated that HPCVD is a simple but effective
technique for the application in the production of MgB2 wires.
MgB2 Thick Film Grown on Silicon Carbide Substrate by Hybrid Physical-Chemical Vapor Deposition
Authors: Li Fen , Guo Tao , Zhang Kai Cheng , Chen Li Ping , Chen Chin Ping , Feng Qing Rong
Published: March 2009

We have successfully synthesized MgB2 thick films on 4H-SiC substrate by hybrid
physical-chemical deposition (HPCVD). They have TC above 40 K, X-ray diffraction (XRD) shows
the polycrystal bulk like structure. And JC estimated using magnetic hysteresis loops (MHLs) and
Bean model is 7.4 MA/cm2 in self field, at 5 K.
Study on Electromagnetic Vibration Casting (EVC) of Magnesium Alloys
Authors: Le Qi Chi , Guo Shi Jie , Zhang Zi Qiang , Cui Jian Zhong , Zhao Z.Z.
Published: March 2009

Electromagnetic Vibration Casting (EVC) is a new effective technical processing for
optimizing solidification microstructures of light alloys. In this paper, this technology was induced
into magnesium alloy DC casting for providing high-quality large diameter billets. The effects of
vibration frequency and current intensities on the microstructures of large diameter billets were
investigated. The results indicate that electromagnetic vibration would refine grains and the reduce
macrosegregation effectively.
Study of the Phase Formation of Sol-Gel YBa2Cu3O7-x Samples in Flowing Oxygen Atmosphere
Authors: Luo Ting , Zhang Yi , Feng Qing Rong
Published: March 2009

The relationship of the resistivity versus synthesizing temperature of sol-gel YBa2Cu3O7-x
samples, with Tc 91K, was studied while synthesizing in flowing oxygen atmosphere. A set of
high temperature -T curves were obtained for the whole process. After four rounds of
synthesizing, the resistivity of the sample was =1.00×10-3cm at room temperature. The -T
curve of the last round also showed that the orthorhombic to tetragonal phase transformation of the
sample occurred around 600oC that is lower than the YBa2Cu3O7-x sample prepared in ambient
atmosphere. Other measurements such as X-ray diffraction, SEM measurement, low temperature
R-T and M-T measurement were also taken to get more information of these samples.
Effect of the Moving Speed between Magnet and Superconductor on the Levitation Force of Single-Domain YBCO Bulk
Authors: Zhu S.H. , Yang W.M. , Wu X.L. , Guo J.Z. , Lu T.N. , Xi S.B.
Published: March 2009

The effect of the moving speed between a permanent magnet and a superconductor on the
levitation force of single-domain YBCO bulk has been studied at liquid nitrogen temperature. It is
found that the levitation force is much different with different moving speed, the maximum levitation
force and the stiffness of the force-distance curve are increasing first and then decreasing with the
increasing of the moving speed and, there is a reasonable speed to get the maximum levitation force. It
is also found that the maximum attractive force is decreasing with the increasing of the moving speed.
Preparation and Properties of Ceramic Tiles for Heat Insulation
Authors: Sun Chen Cheng , Hu Zi Jun , Li Tong Qi , Zhang Hong Bo , Sun Zhi Jie , Zhang Zuo Guang
Published: March 2009

The bulk tiles of ceramic fibers reinforced aerogel were prepared from two reinforcements,
evenly dispersed ceramic fibers and sintered tiles. It has been found that ceramic fiber-reinforced
aerogels showed higher thermal conductivity than aerogel itself. Shrinkage of aerogels in chopped
fiber reinforced aerogel composites showed similar tendency as pure aerogel during gelation, but the
shrinkage was prohibited during supercritical drying. By contrary, in the case of sintered tile
reinforced aerogel, shrinkage of aerogel was completely limited in both gelation and drying processes.
Average of about 50% increase of compressive strengths of the sintered tile reinforced aerogel to
sintered tiles were obtained with an average density increase of about 36%, their thermal conductivity
depressed slightly.
Study of a Ceramic Thermocouple for Al Production
Authors: Feng L.C. , Zhen Liang , Shao Wen Zhu , Xie N.
Published: March 2009

A ceramic thermocouple (CTC) was assembled using SiC as the cathode and MoSi2 as the
anode for the temperature test of the aluminum electrolysis. The NiFe2O4 was sprayed on the surface
of SiC cathode for increasing the corrosion resistance ability in the cryolite. The corrosion behavior of
NiFe2O4 in the cryolite was investigated. The results of the corrosion tests show that the NiFe2O4 has
a very low corrosion rate in the cryolite, and a corrosion layer was formed during the corrosion test.
The mechanisms of the NiFe2O4 corrosion are reactive corrosion and particles flaking. The thermo
emf of SiC-MoSi2 CTC was tested from 25 °C to 1300 °C in air. The results show that thermo emf has
a linear relationship with the temperature dependence, and reached 350 mV at 1300 °C. The CTC
which consists of SiC-MoSi2 prepared in the same batch has a preferable interchangeability. By
holding temperature at 1300 °C, the deviation of thermo emf is 0.5 %, which is better than the
criterion of industry thermocouple, 0.75 %. The CTC response time was also analyzed.
Adaptive Vibration Control on Six Degree-of-Freedom Magnetostrictive Smart Structure
Authors: Li Chao , Mao Jian Qin
Published: March 2009

Multiple degree-of-freedom (DOF) vibration isolation is essential for precision control of
space-borne structures and weapon systems. A new design and analysis of actuators employing
magnetostrictive material TbDyFe is presented. Then, this paper studies the design and control
problems of a six DOF Stewart platform using the concept of cubic configuration. Optimal geometry
for the sensor configuration to get best signal is designed. To control the smart structure, a real time
computer control system is built. Improved robust adaptive filtering algorithm based on nonlinear
constitutive relation proposed in this paper and used in the computer control system. More than 20 dB
of vibration attenuation is achieved in real-time experiments.
Heusler Type CoNiGa Alloys with High Martensitic Transformation Temperature
Authors: Ma Yun Qing , Jiang Cheng Bao , Li Yan , Wang Cui Ping , Liu Xing Jun
Published: March 2009

A strong need exists to develop new kinds of high-temperature shape-memory alloys. In
this study, two series of CoNiGa alloys with different compositions have been studied to investigate
their potentials as high-temperature shape-memory alloys, with regard to their microstructure, crystal
structure, and martensitic transformation behavior. Optical observations and X-ray diffractions
confirmed that single martensite phase was present for low cobalt samples, and dual phases
containing martensite and γ phase were present for high cobalt samples. It was also found that
CoNiGa alloys in this study exhibit austenitic transformation temperatures higher than 340°C,
showing their great potentials for developing as high-temperature shape-memory alloys.
Design and Modal Analysis of Fast Magnetostrictive Steering Mirror
Authors: Yong Yang , Lin Li , Chao Li
Published: March 2009

In this paper the mechanical structure and the operating principle of a fast steering mirror
(FSM) are introduced, and a novel FSM based on magnetostrictive actuators is designed. The modal
analysis of the FSM is carried out with the help of the finite element method, and relative experiments
are also conducted. The experimental results and that of simulation are given and in good qualitative
agreement with each other. This paper pays attention to ameliorating the FSM structure for higher
mechanical natural frequency and perfect control performance. The experimental results would be
helpful for the construction design of the FSM.
Fabrication of Mo/Cu Functional Graded Material by Resistance Sintering under Ultra-High Pressure
Authors: Du Juan , Zhou Zhang Jian , Song Shu Xiang , Zhong Zhi Hong , Ge Chang Chun
Published: March 2009

A new resistance sintering method under ultra high pressure has been developed for
fabrication of Mo/Cu (functional graded material) FGM. The consolidation was carried out under
pressure of 8GPa, and input power of 15kW for 50s. The relative density of the FGM specimen was
upwards 98% and the composition distribution was nearly the same as designed one. The
micro-hardness and bend strength were measured to evaluate the sintering effects. The densification
effect and microstructure of these FGM samples were investigated and the sintering mechanism was
discussed.
The Dispersion of MWCNTs within Epoxy by Treatment with Coupling and Dispersing Agents
Authors: Zhao Yan , Duan Yue Xin
Published: March 2009

The dispersion of CNTs (Carbon Nanotubes) within polymer matrix is a big obstruction to
restrict the application of CNTs. In this paper, the dispersion of MWCNTs(Multi-walled Carbon
Nanotubes) within epoxy resin, which was improved by the coupling agent Volan and dispersing
agent BYK, were studied. It showed that the best dispersing result of MWCNTs was obtained by
combination treatment of Volan and BYK.
Effect of Second Phase on the Mechanical Properties of Mg-Al-Zn Alloy by Equal Channel Angular Extrusion
Authors: Ding Wen Jiang , Jin Li , Lin Dong Liang , Zeng Xiao Qin , Mao Da Li
Published: March 2009

The effect of second phase on the mechanical properties of AZ61 and AZ91 Mg-Al-Zn
magnesium alloy processed by equal-channel angular extrusion (ECAE) has been investigated. The
results revealed that cracks initiated at and propagated through the α-Mg/β-Mg17Al12 interfaces and
grain boundaries of Mg-Al-Zn alloys during tensile deformation. For AZ61, the elongation increased
with the increase of ECAE pass number and the decrease of grain size. However, the elongation of
AZ91 with more second phase particles decreased with the increase of ECAE pass number and the
decrease of grain size.
Fracture Mechanism Analysis of Mg-9Gd-4Y-0.6Zr Alloy
Authors: Zhang Xin Ming , Xiao Yang
Published: March 2009

The fractographs of Mg-9Gd-4Y-0.6Zr alloy specimens which were tensioned at different
temperatures were investigated by optical and scanning electron microscopy, respectively. The
results showed that different slip systems were activated at different temperatures, which were
responsible for varied deformation mechanisms and fracture mechanisms. At 25 °C, the enabled slip
systems were few and only the slip systems on basal plane were able to be activated, so cleavage
fracture was observed. At −196°Cthe number of enabled slip systems increased, prismatic or
pyramidal slip maybe occurred, so that an obvious low-temperature plasticity was observed, while
fracture mechanisms were mainly microvoid coalescence fracture with cleavage fracture in local
areas. At 250 °C, 300 °C and 350 °C, the multisystem slips on the basal planes, the prismatic planes
and the pyramidal planes were able to be activated, while fracture mechanisms were also microviod
coalescence fracture. At 400 °C, recrystallization happened, grain-boundary sliding in new fine
recrystallized grains made the plastic deformation easy, showing coarse-grain superplasticity
phenomenon, and an intergranular shear fracture took place.
Influence of Deformation on Precipitation and Recrystallization in an AZ80 Magnesium Alloy
Authors: Xie Q.G. , Yang Ping , Cui F.E.
Published: March 2009

Cellular precipitation is reduced greatly by deformation at all ageing temperatures.
Precipitates within twins are often nodular and sluggish to grow, whereas dislocations created by
basal slip in matrices promote fast growth of plate-like precipitates. Recrystallization was observed
concurrent with precipitation above 310°C. Effective nucleation sites for recrystallization are
positions connecting twins and grain boundaries or the intersections of twin variants.
The Influence of Zinc and Zirconium on the Microstructure of the As-Cast Magnesium Alloy ZK60
Authors: Ma Yan Long , Pan Fu Sheng , Zuo Ru Lin , Zhang Jin , Yang Ming Bo
Published: March 2009

In the present paper, nine kinds of alloys with different contents of zinc and zirconium were
cast and the influence of zinc and zirconium individually and jointly on the microstructure of the ZK
alloys were investigated. The results indicated that the shape and amount of the eutectic were closely
related to the content of Zn. With the increase of Zn content, the eutectic was prone to have
fish-bone-like shape. When the eutectic grew up to contact with each other, then network eutectic
formed; Zr could intensively refine not only the grain size but also the eutectic, but when Zr>0.6%,
compound containing Zr or pure Zr granules would appear. That the increase of the Zn must go with
the increase of the Zr proved the combined influence of the two alloy elements.
Superplastic Forming Limit and Instability of AZ31B Sheet
Authors: Wang Ling Yun , Song Mei Juan , Liu Rao Chuan
Published: March 2009

The superplastic bulging test of AZ31B magnesium alloy sheet of 0.6mm thick was
carried out on Alliance RT/50 tensile machine at 573K and 3.3×10 −4 −1 s . It is found that either in
tensile-compressive deformation or in bi-axis tensile deformation, the judgment criterion for local
necking of superplastic deformation is 0 2 dε = . The superplastic forming limit diagramFLDat
573K and 3.3×10 −4 −1 s was established for the first time.
Preparation of Mg-Sr Alloys Using Vacuum Reduction: A Thermodynamics Approach
Authors: Xie Wei Dong , Peng Xiao Dong , Wei Qun Yi , Nie Hua , Wang Shou Cheng
Published: March 2009

At the present Mg-Sr alloy is usually produced by alloy mixing process or
melt-leaching-reduction process which has low productivity. A new process has been developed
termed “Preparation Mg-Sr alloys using vacuum thermal reduction”. The principle and procedure of
the new process were discussed in this paper. The reduction thermodynamics was analyzed, including
establishing the oxygen potential diagram of Sr, Mg, Si and Al, determination of main reactions, and
evaluation of Gibbs free energy in vacuum. The results showed that Mg-Sr alloys can be obtained by
synchronous reduction of SrO and MgO from a mixture of MgO, SrO, Si, CaO. The equipment,
reduction temperature and vacuum for the new process have been also discussed.
Nickel Foam Reinforced AZ91 Magnesium Alloy
Authors: Qiu Ke Qiang , Liu Yan Qiu , Suo Z.Y. , Ren Y.L. , Liu Zhen
Published: March 2009

Nickel foam reinforced AZ91 magnesium alloy was fabricated by using melt infiltration
and water quenching methods. The mechanical properties were measured in compressive and tensile
deformation modes. Fracture surfaces were examined by scanning electronic microscopy. The results
show that addition of nickel foam results in a significant increase in elastic modulus, yield strength of
the composite material. However, ductility of the composite was adversely affected when compared
to the unreinforced monolithic counterpart.
Mechanical Behavior of Gas Tungsten Arc Surface Modified Composite Layer on Mg Alloy AZ31 with SiCp and Aluminum
Authors: Jiang Hai Yan , Ding Wen Bin , Zeng Xiao Qin , Li De Hui , Yao Shou Shan
Published: March 2009

Gas tungsten arc (GTA) surface modification process was used to deposit SiC particles and
aluminum alloy powders on the surface of magnesium alloy AZ31. This method is an effective technique in
producing a high performance composite layer. This process result notable grain refinement in the GTA
surface modified composite layer. The hardness and wear resistance of the GTA surface modified
composite layer are superior to that of as-received magnesium alloy AZ31. The hardness values and wear
resistance of GTA surface modified composite layer depend on the GTA process parameters and the SiC
particles powder concentration and distribution. The optimum processing parameters for the formation of a
homogeneous crack/defect-free and grain refinement microstructure were established.
Processing, Microstructure and Mechanical Properties of SiCp/AZ91 Mg Matrix Composites Fabricated by Squeeze Casting
Authors: Qiu X. , Wang Xiao Jun , Zheng Ming Yi , Wu Kun
Published: March 2009

The fabrication processing, mechanical properties and fracture characters of SiCp/AZ91
magnesium matrix composites fabricated by squeeze casting were investigated. The SiC particles
with different diameters (5μm, 20μm and 50μm) were employed as the reinforcement in the
composites, the volume fraction of them was 50% in all cases. Experimental results showed that when
the size of SiC particle decreased, the tensile properties of the composite increased. The tensile
properties of SiCp/AZ91 composite with small particles are controlled by the properties of matrix
alloy and the strength of the interface between the matrix and reinforcements, but the composites
reinforced by large particles are controlled by the fracture of the particles.
Surface Modification of Magnesium with Rare Earth Conversion Films for Biomedical Protection
Authors: Gao Jia Cheng , Xue Yan , Qiao Li Ying , Wang Yong , Zhang Yan
Published: March 2009

The specific gravity and elastic modulus of magnesium alloys are similar to that of human
bone. Magnesium is one of the most important elements in the human body and plays a key role in the
metabolic process. But the application of magnesium is seriously limited as a biomaterial since it
corrodes easily in the physiological environment of the body. In order to reduce the corrosion, we
developed protective films using rare earth (RE) conversion processing. The surface of magnesium
samples was modified by contact with different rare-earth salt solutions; then the samples were
dipped in SBF to test their corrosion resistance. The change of mass and the pH of the solutions were
measured continuously using an electronic scale and a pH micrometer. The surface microstructure of
the samples was observed by XRD and metallomicroscope. Corrosion rates of the samples in SBF
were determined using Taffier curve. The preliminary results show that the conversion treatment with
CeCl3 or Y(NO3)3 can improve the corrosion resistance of magnesium in SBF. The relationship of the
RE salts concentration and the corrosion properties were studied,the best combination of parameters
was determined, and the formation mechanism of rare-earth conversion film has been also elaborated.
Interfacial Reaction in Al Matrix Composites Reinforced by Mg Borate Whisker
Authors: Wu Pei Lian , Wang Li Dong , Fei Wei Dong
Published: March 2009

In the present study, MBOw/Al composites were fabricated using squeeze casting method.
The interfacial reaction in the composite was investigated using transmission electron microscope
(TEM). The tensile properties of the composites with different kinds of matrix were studied. The
experimental results showed that the properties of the composite were very good.
Effects of Microstructure and Partial Melting on Tensile Properties of AZ91 Magnesium Cast Alloy
Authors: Zhu Tian Ping , Chen Zhan W. , Gao Wei
Published: March 2009

Mechanical properties of AZ91 cast alloy depend strongly on the morphology (size and
distribution) of the second (β-Mg17Al12) phase. It was observed that low ductility of AZ91 alloy was
attributed to the brittle nature of the β phase particles at which microcracks initiated. These
microcracks then coalesced contributing to the fracture of alloy. Quantitative study on microcracking
progress revealed that cast samples with coarse microstructures fractured at low strain due to the
non-uniform distribution of bulk blocky β particles at interdendrite region. These fracture surfaces
exhibited clear cleavage mode. Fine cast microstructure presented quasicleavage fracture mode with
clear dimple and tear ridges. The partial melting (and resolidification) heat treatment improved tensile
properties, which was in disagreement with the available data from literature.
Microstructural Characterization of Sprayed Aluminum Matrix Composites Reinforced by SiC Particles
Authors: Hu Ming , Hu Hai Ting , Hong Zheng Xiao , Kang Suk Bong , Euh Kwang Jun
Published: March 2009

The microstructures of sprayed SiCp/Al composite fabricated by thermal spraying
technique by optical microscope (OM)scanning electronic microscope (SEM), transmission
electronic microscope (TEM), X-ray (diffractometer) XRD, selected area electron diffraction
(SAED), energy dispersive spectrum (EDS) techniques, were investigated. The composite consisted
of SiC and Al, along with single crystal Si and amorphorous Si, and tiny Al2O3. The interfaces
between SiC particles and Al matrix bonded well, and tiny reactants like Al2O3 were found near the
interfaces. The mechanisms of chemical reactions during sprayin were discussed g. The nano-Al
grains and particles were observed in the sprayed composite. The formation of nano-Al grains and
particles of SiCp/ Al composites were explained. It has been found that Several interface relationships
existed in the sprayed composite.
Effect of Current Density on Morphology and Corrosion Resistance of Anodized Coating on SiCp/2024 Al Composite
Authors: He Chun Lin , Cai Qing Kui
Published: March 2009

The effects of current densities on the morphology and corrosion resistance of anodized
coating formed on a SiCp/2024 Al metal matrix composite (MMC) in sulfuric acid solution were
investigated by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and
polarization curve. The results showed that the surface of the coating was not flat, and cracks existed
when the current density increased to 20mA/cm2. The SiC particles could be oxidized during
anodizing of the MMC. And the SiC particle anodized at a significantly reduced rate compared with
the adjacent Al matrix. This gave rise to alumina film encroachment beneath the particle and
occlusion of the partly anodized particle in the coating. As a consequence, the oxide/substrate
interface became locally scalloped, and the anodized coating was non-uniform in thickness. Further,
oxidation of SiC appeared to be associated with gas-filled cavities in the coating material. The size of
cavities above the SiC particles increased obviously and the surface cracks developed when the
current density increased. This shows that the anodized coating formed at higher current density has a
structural feature with lower corrosion resistance. The polarization results indicated that the
corrosion resistance of the coating decreases when the current density increases.
Investigation of Inhomogeneous Deformation on Meso-Scale with Crystal Plasticity Finite Element
Authors: Zhang Xin Ming , Tang Jian Guo , Deng Yun Lai , Zhou Zhuo Ping
Published: March 2009

The influence of crystallographic orientation stability on the inhomogeneous deformation
on the meso-scale was numerically simulated with the crystal plasticity finite element. The initial
microstructures were introduced into the finite element via intra-granular orientation gradient. The
results demonstrated that the average orientation for both stable Goss and meta-stable cube oriented
grains changed very little in plane strain compression (PSC). And for stable Goss oriented grain, the
orientation gradient increased slightly, but for meta-stable cube oriented grain, the orientation
gradient increased dramatically. And in spite of the same Taylor factor for both oriented grains, the
dissipated averaged energy for cube oriented grain was higher than for Goss oriented grains, and the
distribution width of dissipated work in cube oriented grain was also wider than that in Goss oriented
grain. Furthermore, there was also strong energy gradient in PSC of cube oriented grain. Both the
orientation gradient and energy gradient favor the nucleation of cube grains during recrystallization.
Particle-Stimulated Nucleation of Recrystallization for Grain-Size Control in 01420 Al-Li Alloy
Authors: Ye Ling Ying , Zhang Xin Ming , Du Yu Xuan , Luo Zhi Hui
Published: March 2009

Grain refinement of 01420 Al-Li alloy through particle stimulated nucleation(PSN) of
recrystallization is reported. The results showed that the rolling in the overaged 01420 Al-Li alloy
resulted in the formation of the deformation zones associated with the second phase particles larger
than 0.80 μm which can act as the nucleation sites for recrystallized grains. The precipitates larger
than 0.80 μm are sticked shaped S-phase(Al2MgLi) and globular β-phase(Mg2Al3), and the density of
β-phase particles is approximately as two to three times as the S-phase particles. The S-phase
particles can’t be as PSN sites since they were broken to small dispersoid particles during rolling. The
average grain size of 01420 Al-Li alloy solutioned at 470°C for 2h, aged at 300 °C for 48h, 81% rolled
at 300 °C and finally recrystallized at 500 °C for 10min is approximately 10 μm.
Grain Boundary Migration and Compensation Effect
Authors: Lejček Pavel
Published: March 2009

Anisotropy of grain boundary motion in a Fe–6at.%Si alloy is represented by a spectrum of values of the activation enthalpy of migration and the pre-exponential factor, depending on the orientation of individual grain boundaries. The general plot of these values exhibits a pronounced linear interdependence called the compensation effect. It is shown that changes of these values, caused by changes of intensive variables, are thermodynamically consistent.
Static Recrystallization of Austenite in a Medium-Carbon Vanadium Microalloyed Steel and Inhibition by Strain-Induced Precipitates
Authors: Gómez Manuel , Medina S.F. , Chaves J.I.
Published: March 2009

The austenite static recrystallization kinetics at several temperatures and the recrystallization-precipitation-time- temperature (RPTT) diagrams of a medium-carbon vanadium microalloyed steel have been determined for a strain ε = 0.35. Unlike many other studies carried out previously on V microalloyed steels, the recrystallized fraction against time curves showed the formation of a double plateau that indicates two stages of inhibition of recrystallization due to the formation of different types of strain induced precipitates. This work makes use of transmission electron microscopy to study the nature and size distribution of these precipitates capable of inhibiting recrystallization. The values of driving and pinning forces for static recrystallization are calculated and an analysis of the relationship between the net balance of these forces, the precipitation state and the progress or inhibition of the recrystallization is accomplished. A value of driving force that decreases as recrystallized fraction grows during isothermal holding time is estimated and helps to interpret the behavior of austenite after deformation.
Modelling the Precipitation of Al3X Dispersoids in Aluminium Alloys and their Effect on Recrystallization
Authors: Robson Joseph D. , Prangnell Philip B. , McKay Brian J. , Heason Chris P.
Published: March 2009

A combined model is presented that predicts the non-uniform distribution of Al3X dispersoid particles in commercial aluminium alloys containing zirconium and scandium and uses these predictions as inputs to a simple recrystallization model. The recrystallization model relies on knowledge of the stored energy in the sub-structure after deformation and this has been measured using electron backscattered diffraction (EBSD) techniques. The recrystallization model is based on the concept that partial recrystallization results from the non-uniform distribution of dispersoid particles due to their precipitation from a segregated cast structure. The model has been used to devise an improved homogenization treatment for AA7050, which uses an isothermal hold during heat up to maximize dispersoid nucleation. It has also been applied to predict the effect of scandium additions on recrystallization, investigate the factors that control the through thickness variation in recrystallized fraction, and interpret the results of experiments where the effect of strain rate have been studied.
Normal Grain Growth in Three Dimensions: Monte Carlo Potts Model Simulation and Mean-Field Theory
Authors: Zöllner Dana , Streitenberger Peter
Published: March 2009

A modified Monte Carlo Potts model algorithm for single-phase normal grain growth in three dimensions in presented, which enables an extensive statistical analysis of the growth kinetics and topological properties of the microstructure within the quasi-stationary self-similar coarsening regime. From the mean-field theory an analytical grain size distribution function is derived, which is based on a quadratic approximation of the average self-similar volumetric rate of change as a function of the relative grain size as it has been determined from the simulation. The analytical size distribution function is found to be in excellent agreement with the simulation results.
Modelling Nucleation of Recrystallisation in Aluminium Alloys
Authors: Schäfer C. , Crumbach Mischa , Gottstein Günter
Published: March 2009

The predictions from a grain cluster deformation texture model, GIA, are utilized to study the nucleation texture of recrystallisation of aluminium alloys. In combination with a dislocation based work hardening model, the propensity of specific grains in their granular environment for select nucleation mechanisms is investigated. Quantitative criteria for the nucleation events can be formulated. The results can be fed into a growth model of recrystallisation to predict recrystallisation textures and lend themselves to through-process modelling.
Diffusion Bonding of Aluminum Alloy Using a High-Boiling Liquid Protection
Authors: Xie Lan Sheng , Sui Y.
Published: March 2009

This paper presents a diffusion bonding technology at vacuum using a high-boiling liquid
protection, diethylene glycol dimethyl ether (C6H19O3). After washing in alcohol, the specimens were
immersed in diethylene glycol dimethyl ether. Before heating, the vacuum chamber was vacuumized
to about 10-1Pa. Then chamber was heated to about 80°C, and held for 20 minute to evaporate the
liquid protection in order to make the clean bonding surfaces contact. Metallographic observations of
the interface by optical microscope were carried out. The experimental results show that the
protections have successfully protected the bonding surfaces from re-oxidation prior to bonding. The
metallographs show that the vacancies at the bonding interface bonding at 560°C for 2 hours are
obvious and the materials at the interfaces of specimens bonded under the pressure of 5 MPa at 535°C
for 2 hours were well joined.
The ASTM International Standard Test Method for Determining the Superplastic Properties of Metallic Materials
Authors: Comley Peter N.
Published: March 2009

Over the last 40 years there have been many papers published showing superplastic
properties of metallic materials. However there has been no standardized test available to assess and
compare material, and researchers and companies in the field have devised a number of different
methods to show superplastic properties. The value of these properties can vary dependent on the test
method used.
ASTM International (formerly The American Society for Testing and Materials ) has developed a
standardized test method for superplastic properties. The standard is intended for all to use as a
common platform for testing, evaluating and publishing superplastic properties to a uniform format,
useful for both academia and industry.
The paper outlines the main points of the standard, including:-
The coupon geometry and the method of clamping the coupon in the grips.
The furnace and test machine requirements.
The testing conditions and the method of pulling the coupon.
The analysis of the load and extension data from the test, and the standard presentation of superplastic
properties.
The basic superplastic properties of stress versus strain for any particular constant strain rate.
The method to determine ‘m’, using a step method at a particular strain.
Some data is presented showing how the properties of fine grain Ti-6Al-4V titanium alloy are derived
and presented using the standard.
Mechanisms of Microsuperplasticity
Authors: Robinson J.H. , Rust Martin A. , Todd Richard I.
Published: March 2009

After superplastic deformation of Al-7475 and some other aluminium alloys, straininduced
cavities are seen to be associated with long fibres parallel to the tensile direction. These
fibres, whiskers or filaments are also observed on the fracture surface. This effect has become
known as microsuperplasticity.
The whisker characteristics are affected by the deformation conditions, particularly temperature
and strain rate. To study the effect of these variables more fully, tensile samples of Al 7475 have
been strained to failure at temperatures ranging from 480OC to 530OC and strain rates from 1.0E-
04s-1 to 5.0E-03s-1. Additional samples were deformed at 450OC and 420OC and a single strain rate.
Some whiskering was observed under all testing conditions. The longest whiskers were generally
seen at high temperatures and low strain rates. A TEM study of macroscopic whiskers produced
under conditions of around 540OC and 1.0E-04 /s showed an amorphous structure. Annealing prior
to deformation was shown to have little effect on whisker formation.
EDX analysis showed the whole surface of the alloy to be enriched in alloying elements
compared with the bulk alloy. The high levels of Mg detected were connected with the formation of
magnesia as the surface oxide verified using Cr3+ fluorescence microscopy. Use of the differential
scanning calorimeter (DSC) showed no conclusive evidence of partial melting below the testing
temperatures. Considerations of capillarity and the DSC analysis suggest whiskering did not occur
by a mechanism of viscous flow.
Influence of Diffusion Bonding for Superplasticity Magnesium Alloys with the Fore and Post Treatment
Authors: Yu Yan Dong , Wang C.W.
Published: March 2009

Influence of surface treatment to diffusion bonding before joining was analyzed during the
process of magnesium alloys diffusion bonding. We processed diffusion bonding by using ZK60
rolling superplasticity magnesium alloy sheets with thickness 1.5mm and grain size 8.9$m. Joint was
carried out ageing strengthening by experiment study to increase its shearing strength. Ageing
strengthening performance was researched under ageing temperature 150-190 °C and the ageing time
6-48h. The results showed: diffusion bonding joints’ shearing strength had enhanced in some degrees
and reached 86% of basal strength when the ageing temperature is 160 °C and the ageing time is 24h.
It showed that the magnesium alloy joint’s strength could be greatly improved by ageing
strengthening.
Superplasticity in Ultrahigh Carbon (1.6 Pct C) Steel
Authors: Zhang Zhan Ling , Liu Yong Ning , Zhu Jie Wu , Yu G.
Published: March 2009

Ultrahigh carbon steel containing 1.6 wt pct C was processed to create microduplex
structure consisting of fine-spheroidized carbides and fine ferrite grains. Elongation-to-failure tests
were conducted at strain rates from 10-4s-1 to 15×10-4s-1, and at temperatures from 600 °C to 850 °C.
The steel exhibited superplasticity at and above 700 °C when testing at a strain rate of 10-4s-1, and at
800 °C when testing at strain rates of 7×10-4s-1 and slower. The grains retained the equiaxed shape
and initial size during deformation; dynamic grain growth was not observed after superplastic
deformation, whereas carbide coarsening was observed. It is concluded that the fine ferrite grains or
austensite grains are stabilized by the grain boundary carbides, and grain-boundary sliding
controlled by grain boundary diffusion is the principal superplastic deformation mechanism at
temperatures in the range of 700-850 °C.
Superplastic Forming of Magnesium Alloys: Production of Microstructures, Superplastic Properties, Cavitation Behaviour
Authors: Blandin Jean Jacques
Published: March 2009

Superplastic forming (SPF) of magnesium alloys has received increasing attention in the
recent past. The aim of this presentation is to review recent works dealing with SPF of Mg alloys with
a three-fold objective: i. How to produce fine or ultra fine grained (UFG) microstructures ii. Are
there specifities in superplastic deformation mechanisms iii. How SPF Mg alloys resist to
cavitation Deformation mechanisms as well as damage variations in the superplastic regime will be
preferentially discussed in relation with grain size, content in intermetallic particles and diffusion
kinetics. For the sake of illustration, some results concerning the superplastic behaviour of UFG
magnesium alloys produced by severe plastic deformation will be presented since such
microstructures exhibit particularly attractive superplastic properties at quite low temperatures.
Superplasticity in Ultrafine Grained Magnesium Alloy AZ31 Prepared by Accumulative Roll Bonding
Authors: Wang Qing Feng , Xiao X.P. , Chen X.J. , Chen W.
Published: March 2009

In this paper, an ultra-fine grained AZ31 magnesium alloy sheet with grain size less than
3μm was generated by three-run accumulative roll bonding of as cast alloy at a deformation
temperature of 350°C and a reduction of 80% for each pass. The microstructures on the different ARB
stages were observed and superplasticity examination in the ultrafine grained AZ31 alloy were carried
out at a fixed temperature of 300°C and varied strain rate ranging from 10-4 to 10-1 s-1. It is indicated
that significant grain refinement was mainly achieved in the first run and gradual uniformity of grain
size in the next by continuous dynamic recrystalization. Besides, a superplastic deformation with a
moderate elongation-to-fracture of 316% was obtained at a strain rate of 10-2 s-1 indicating a low
temperature and high strain rate superplasticity, while a maximum elongation-to-fracture of 562%
at10-4 s-1. The strain rate sensitivity exponent as high as of 0.34-0.41 implies the dominant role of
grain boundary sliding in superplastic deformation at strain rate ranging from 10-3 to 10-2 s-1. The
results indicate a possible approach to produce magnesium alloy sheet with fine grain and excellent
deep drawing workability.
Finite Element Modeling of Superplastic Forming in the Presence of Back Pressure
Authors: Nazzal Mohammad , Khraisheh Marwan K.
Published: March 2009

It is established that some superplastic materials undergo significant cavitation during
deformation. Cavitation not only limits the superplastic ductility of the material, but also reduces the
service properties and the fatigue performance of the formed parts. Experimental results have shown
that an effective method to eliminate cavitation is the application of hydrostatic pressure during
deformation. In this work, finite element simulations are carried out to study the effects of hydrostatic
pressure on damage evolution during SPF. The analysis is conducted for the superplastic copper based
alloy Coronze-638 at 550 °C. The results clearly demonstrate the effectiveness of the superimposition
of hydrostatic pressure in reducing the amount of cavities generated during SPF and improving the
integrity of the formed part.
Comparative Study of Element Formulation on Simulation of Superplastic Forming
Authors: Xu X.F. , Tang L.M. , Tong G.Q.
Published: March 2009

A comparative study of different element formulations in simulating superplastic forming
with the MARC finite element code is performed in the paper. Simulations were accomplished with
solid, shell, membrane elements to predict forming characteristics and pressure-time curves. Finite
element analysis (FEA) predictions of SPF pressure-time curves were found to be greatly affected by
the element type and the strain rate control algorithms. Two strain rate control algorithms were
applied in the present study: an algorithm based on limiting the rate of deformation with the average
strain rate of all the elements, i.e. the build-in method in MARC, and a second algorithm which limits
the rate of deformation based on the average strain rate of the elements with the 20 highest strain rates.
The resulting pressure-time curves for each of these formulations were compared with respect to each
type of element. Under the guide of the analysis, the die was fabricated and the AA5083 bracket was
successfully manufactured. Good agreement was obtained between predicted and measured thickness
in the part.
Fibre Reinforced Refractory Castables :An Alternative Solution for SPF Die Manufacturing
Authors: Bernhart Gérard , Nazaret F. , Cutard T.
Published: March 2009

Today heat resistant cast steels are the nominal solution for Ti-SPF forming die
manufacturing. Nevertheless, this materials present some drawbacks related to delivery time and cost.
A fibre reinforced refractory castable (FRRC) is proposed as a new solution for prototype SPF die
manufacturing. Due to the general brittleness of refractory castables, a short fibre reinforcement has
been investigated in order to avoid catastrophic failure during the forming process. General
macroscopic behavior of such materials is very complex and presents large evolutions with the testing
temperature. The paper addresses the important benefits of the reinforcement for refractory castable in
the case of loading on a complex structure. The capability of the material to support several cracks is
shown in the case of a technological sample with a complex shape.
The Effect of Grain Size on Superplastic Deformation of Ti-6Al-4V Alloy
Authors: Zhao Wen Juan , Ding Hua , Song D. , Cao F.R. , Hou Hong Liang
Published: March 2009

In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different
initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of
1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms,
the microstructures of deformed alloy were investigated by using an optical microscope and
transmission electron microscope (TEM). The results indicate that there is dramatic difference in the
superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth
induced by superplastic deformation has also been clearly observed during deformation process, and
the grain growth model including the static and strain induced part during superplastic deformation
was utilized to analyze the data of Ti-6Al-4V alloy.