bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Interface Reactions between Nb-Si System In Situ Composite and Ceramics
Authors: Yu Jing Jing , Li Shu Suo , Han Ya Fang
Published: March 2009

A Nb-Si system in-situ composite Nb-16Si-24Ti-6Cr-6Al-2Hf(at%) was fabricated using
vacuum arc melting method, and then was metallurgically reacted with four kinds of ceramics ZrO2,
Y2O3 stabilized ZrO2, Y2O3, SiC+Si3N4 at elevated temperature. The microstructures in the interface
reaction zones were investigated by SEM and EDS. The results showed that different extent chemical
reactions between the composite and these four kinds of ceramics took place. It has been found that
HfO2 riched layer formed near the interfaces between the Nb-Si in-situ composite and three ceramics
of ZrO2, Y2O3 stabilized ZrO2 and Y2O3, and thickness of the reaction zones were about 100μm,
10μm, 1μm respectively. C and N elements in SiC+Si3N4 ceramic diffused to the composite at
elevated temperature, and a new phase that rich of Ti, C and N elements appeared nearby the interface
and accumulated inhomogenously. It may be concluded that the interface reactions of both ZrO2 and
SiC+Si3N4 with Nb-Si composite were very violent, therefore they are not suitable as face-coat
materials of shell molds for investment casting; the interface reaction of Y2O3 stabilized ZrO2 and
Nb-Si composite was slighter than ZrO2 and SiC+Si3N4, and it can be used as face-coat material of
shell molds, the interface reaction of Y2O3 and Nb-Si composite was very slight, and is recommended
as an ideal face-coat materials of shell molds.
Preparation and Mechanical Properties of C/C-SiC Composites
Authors: Zhu Dong Mei , Du Hong Na , Luo Fa , Zhou Wan Cheng
Published: March 2009

Porous C/C composite with certain porosity prepared by Chemical vapor infiltration
(CVI) was chosen as the preforms to develop the C/C-SiC composites through precursor infiltration
and pyrolysis(PIP), using PCS (polycarbosilane) as the precursor and divinylbenzene as solvent and
cross-linking reagent for PCS. The effect of the infiltration solution with different PCS/DVB ratio on
the final density, microstructure, and mechanical properties of composites was investigated and the
proper PCS/DVB ratio to prepare the C/C-SiC composites was suggested. The experimental results
showed that the final densities and the mechanical properties of the composites were close related to
the PCS/DVB ratio. Higher PCS/DVB ratio resulted in higher final density and better mechanical
properties, but not the highest PCS/DVB ratio could get the best mechanical properties. The main
reason is that too high PCS/DVB ratio will make the infiltration process become difficult and lead to
the formation of lots of pores in the final composite, at last lowers the mechanical properties. It is
believed that the 50% PCS content is proper to prepare the C/C-SiC composites. The composite from
50% PCS infiltration solution could get the final density of1.696g/cm3, the flexural strength of
171Mpa, and shearing strength of 21.6Mpa, which are the best mechanical results among the obtained
materials.
Effects of Interphase Thickness on Damping Behavior of 2D C/SiC Composites
Authors: Zhang Qing , Cheng Lai Fei , Wang Wei , Wei Xi , Zhang Li Tong , Xu Yong Dong
Published: March 2009

Internal friction of 2D C/SiC composites fabricated by chemical vapor infiltration (CVI)
method was measured by dynamical mechanical analysis (DMA) at different frequencies from room
temperature (RT) to 400°C in air atmosphere. Internal friction of 2D C/SiC composites increased
gradually with increasing temperature and then decreased after damping peak appeared in the
temperature range of 250°C to 300°C. Damping capacity and peak value decreased gradually with
increasing frequency, accompanied with a shift of damping peak towards lower temperatures.
Moreover, the effect of interphase thickness on damping behavior of 2D C/SiC composites was
investigated. The results showed that damping peak of the composites increased gradually and the
temperature of the peak shifted to the lower temperature with increasing PyC interphase thickness,
when the interphase thickness is in the range of 90~296nm. The influence of interphase thickness on
interfacial bonding strength, sliding resistance and the microstructure of SiC matrix was discussed,
which was considered to be responsible for the results.
Study on Tensile and High Cycle Fatigue Properties of TiC Particle Reinforced Titanium Matrix Composite
Authors: Zeng Li Ying , Zhao Yong Qing , Mao Xiao Nan , Qi Yun Lian
Published: March 2009

Tensile and high cycle fatigue (HCF) property for TiC particle reinforced titanium matrix
composite has been studied in this paper. The results indicated that the composite possessed favorite
comprehensive properties. The tensile properties for the composite are superior to that of the common
high temperature titanium alloys, e.g. IMI834, Ti-1100. Smooth axial fatigue tests were taken at a
frequency of 76Hz with a load ratio R of 0.06 and –1, respectively. And HCF strength for the
composite at ambient temperature is 595MPa and 494MPa, respectively.
Effects of CaCO3 Modificator on Microstructure and Mechanical Properties of Cast AZ91 Magnesium Alloy
Authors: Wang Qu Dong , Zhao Yang , Li Qing Hua
Published: March 2009

Effects of CaCO3 modificator on microstructure and mechanical properties of cast AZ91
Magnesium alloy have been investigated. Tensile fracture behavior of AZ91 alloys modified by
CaCO3 has also been studied. Results show that CaCO3 modificator can obviously refine the grain of
AZ91 magnesium alloy and Mg17Al12. Mg17Al12 in grain boundary of AZ91 alloy after modified by
CaCO3 changes from continuous reticular structure to discontinuous reticular structure, even so much
as granular structure and rod structure. After modified by 0.5wt% CaCO3 modificator, ultimate tensile
strength, yield strength, impact toughness and elongation of AZ91 alloy increase from 186MPa to
200MPa, from 147MPa to 160MPa, from 4J to 9J and from 2.6% to 5%, respectively. And 0.5wt%
CaCO3 modificator brings about an optimal refining effect. The study also shows that the fracture
mechanism of modified AZ91 alloy is between cleavage fracture and quasi-cleavage fracture, which
is as same as that of unmodified AZ91 alloy.
Light Weight and High Modulus Aluminum Matrix Composite and its Application into Aerospace
Authors: Ouyang Qiu Bao , Li Rui Xiang , Wang Wen Long , Zhang Guo Ding , Zhang Di
Published: March 2009

Compared to the conventional constructive materials, SiC particle reinforced aluminum
matrix composites have lighter weight and higher specific modulus, and are applied in the structure
framework of solar battery array for space station. According to the requests of the material properties
for this framework, aluminum matrix composites are specially designed and manufactured, and then
deformed into components of different shapes and sizes for various uses. The composite components
were of compact structure and excellent mechanical properties, and had passed all the application
tests for the framework. The application of aluminum matrix composites achieves a good result that
not only the framework weight was greatly reduced but also the comprehensive properties of the
framework were improved greatly. Aluminum matrix composites exhibit a great potential for further
application into aerospace.
Design of a Deployable Antenna Actuated by Shape Memory Alloy Hinge
Authors: Lan Xin , Leng Jin Song , Du Shan Yi
Published: March 2009

This paper is concerned about a design of a new deployable antenna actuated by 6 shape
memory alloy (SMA) hinges. The antenna consists of 6 radial, tensioned, parabolic, deployable ribs
connecting to a central hub. The hinge, located at each rib, is used of the Nitinol SMA material due to
the ability to generate large strains and electrical resistive actuation. The elongated SMA wire is
heated by an electrical current, caused to contract in response to a converse thermally-induced phase
transformation. The resulting tension creates a moment, imparting rotary motion between two
adjacent beams. The concept and operation of deployable antenna system are discussed in detail, and
a dynamic simulation is presented. A series of experiments are performed on the SMA actuator to
investigate the system behavior in the process of deployment. Results indicated that the hinge with
low speed rotation and easy fabrication achieves reliable actuation for the deployment of the antenna,
and the antenna demonstrates a high deployment-to-stowage volume ratio.
Investigation on a Novel Low Temperature/Vacuum Bag Cure Prepreg
Authors: Zhang Bao Yan , Li Bin Tai , Chen Xiang Bao , Zhou Zheng Gang
Published: March 2009

A low temperature cure resin has been prepared successfully by applying self
designed/synthesized cure agent and commercial epoxies through slurry mixing process. Low
temperature/vacuum bag cure prepreg with excellent drapeability & spreadability and over 10 days
storage life at room temperature could be prepared by hot/melt technique. The cure and post cure
parameters of manufacturing composites were optimized. The main properties of low
temperature/vacuum bag cure composite have been determined. Results indicated that the low
temperature/vacuum bag cure composite system had excellent mechanical properties and its long
service temperature could reach 80°C. The influence of ultrasonic irradiation applied during the
manufacturing process on the properties of the composite was discussed, and results showed that the
ultrasonic irradiation improved the properties of composite greatly and suggested a novel strategy to
improve the mechanical properties of low temperature cure composite systems.
Quantitative Analysis on Fracture Mechanism of Al Melt Oxidatively Infiltrated SiCp/Al2O3-Al Composites by XPS
Authors: Lv Yi Zhong Hong , Cui Yan
Published: March 2009

The chemical element and its valence at the fracture surface of SiCp/Al2O3-Al
composites synthesized by oxidative infiltration of Al melt were analyzed quantitatively using
X-ray photoelectron spectrometer(XPS), the percentage content of various phase at fracture surface
was determined accordingly. Additionally, the volume fraction of different phase in the composites
was meassured by optical metallographic examination of the three-dimensional section. And then,
by the comparison of phase content between fracture surface and section of the composites, the
preference for the crack penetrating various phases of the composites was identified ,which in turn
micro-fracture mechanisms of the composites were revealed quantitatively. It is proved that SiC
particle size has a critical influence on the percent content of co-continuous Al2O3 and Al phases, as
well as the micro-fracture mechanisms of this kind of composites. Based on the analysis of
micro-fracture mechanisms, the moderate size (about 10μm) of SiC particulate would be beneficial
to the mechanical properties of composites, the tested results of mechanical properties under room
and elevated temperature verified the hypothesis.
Mechanical and Microwave Dielectric Properties of Csf/Si3N4 Composites
Authors: Wang Xiao Yan , Luo Fa , Zhu Dong Mei , Zhou Wan Cheng , Wu Hong Huan
Published: March 2009

Csf/Si3N4 composites were prepared by hot-press sintering method using α-Si3N4 power,
short chopping carbon-fiber and sintering additives. XRD analysis showed that the α-Si3N4 was
almost completely transferred into β-Si3N4. The SEM micrographs of fractured surfaces showed that
special network developed by rod-like β- Si3N4 grains. The flexure strength of 590±10MPa, and
fracture toughness of 7.94±0.1MPa·m1/2 were achieved for the samples incorporated with 0.5wt% the
carbon fibers .The microwave dielectric property of Csf/Si3N4 composites was measured at a
frequency range of 8.2~18GHz by E8362B PNA series network analyzer. The real part (ε ′ ) of the
permittivity of the Csf/Si3N4 composites increases from 10 to 58 with the rise of the content of carbon
fibers in the composites, as well as the imaginary part increases from 0.03 to 98 at frequency of
9.375GHz. A strong frequency dependence of the real part was observed both in X and Ku bands.
In Situ Measurement on the Pressure and Resin Flow in Hot Press Process of Composites
Authors: Gu Y.Z. , Zhang Zuo Guang , Li Min
Published: March 2009

In this paper, the distribution and variation of resin pressure were tested by a specially
designed measuring system, reflecting the resin flow during the process. Based on this system, the
effects of the applied pressure, the lay-up of laminate and the variety of bleeder on resin pressure were
investigated. It indicated that the transfer of resin pressure along the laminate thickness direction was
not instantaneous. The resin pressure of the laminate boundaries and the resin flow behavior both
were influenced by the studied factors. These results are valuable for the modification of the resin
flow model and the precise determination of the boundary conditions.
Optical Absorption Properties of Nanotitanium Dioxide Doped ZnO/Silicone Thermal Control Coating
Authors: Qin Wei , Wu Xiao Hong , Zhao Gui Mei , Lai Xiao Ming , Zhang Li Gong
Published: March 2009

As a kind of white paint, ZnO/silicone thermal control coatings are used commonly in
space. In order to implement more effective thermal control in space, nanotitanium dioxide was doped
to the coatings. In this paper, different percent of nanotitanium dioxide was appended to the coatings,
and thermal control principle was discussed. Optical properties of these coatings were discussed by
spectrophotometry and infrared reflectometer. The experimental results show that solar absorptance
(αs) of nanotitanium dioxide doped ZnO/silicone thermal control coating is lower in all wavelength
region than the coatings without doping, especially in visible region and infrared region. The total
solar absorptance of 1% nanotitanium dioxide doped coating is 0.09, which decreases by 36% than
the undoped coating..
Ti-N-C Films Deposited by Ion Beam Assisted MF Twin Targets Unbalanced Magnetron Sputtering
Authors: Huang Ying , Sun Shao Ni , Wu Yu Feng , Ma Sheng Ge , Zhou Yi
Published: March 2009

Using Hall ion source assisted MF twin targets unbalanced magnetron sputtering, series of
Ti/TiN, Ti/TiN/Ti(C,N) and Ti/TiN/Ti(C,N)/TiC hard anti-wear films are deposited on different
materials like stainless and high speed steels by changing atmosphere, bias mode, sputtering and ion
beam assisted currents. The color, crystal structure, hardness and binding force of film are tested and
analyzed, respectively. Experimental results show that color of film is sensitive to atmosphere, slight
change of atmosphere can influence the coating’s color seriously. The preferred orientation of
Ti(C,N) films prepared by MF twin targets unbalanced magnetron sputtering has no obvious change
compared with the film deposited by other PVD technologies. The substrate material has great
influence on film’s hardness, binding energy and surface modification. The application of Hall
current can effectively improve the binding force between film and substrate.
Effects of Ti-1023 Anodized Coating on Corrosion Behavior of Ti-1023/30CrMnSiA and Ti-1023/LY12 Galvanic Couples
Authors: Liu Jian Hua , Shi Jun Xiu , Li Song Mei , Yi Jun Lan
Published: March 2009

Galvanic properties were evaluated on bare and anodized Ti-1023 titanium alloy which
coupled to Ni-electroplated, Zn-electroplated, Cd-electroplated 30CrMnSiA and anodized LY12,
respectively. Corrosion properties including open circuit potential (Eoc) of each material, galvanic
corrosion potential (Eg), and corrosion current (Ig) of the couples were monitored in conjunction
with a Model 263A potentiostat system. Corrosion current density (Īg) and average value of
corrosion potential (Ēg) were calculated from Ig-time and Eg-time curves, respectively. Corrosion
morphology was observed on a optical microscope (OM) and corrosion mechanisms were analyzed
and discussed. The corrosion resistance of Ti-1023/LY12 couple was significantly improved by
Ti-1023 anodized coating. However, the coating accelerated the dissolve of the three electroplated
coatings in the other galvanic couples, resulting in a heavy corrosion attack on 30CrMnSiA steel.
Coated Conductor: Some Critical Aspects from Substrate to Device
Authors: Odier Philippe , Girard Antoine , Cointe Yannick , Donet S. , Yu Ze Ming , Caroff Tristan , Cavallaro Andrea , Guibadj Abdenacer
Published: March 2009

This work reports some new studies related to critical aspects in the development of
coated conductors (CC). New bi-axially textured tapes based on commercial copper alloys were
fabricated and tested as substrates for LZO buffer layer deposited by chemical solution deposition
(CSD). Such a layer form cube texture on NiW5 and Cu55Ni45 with an identical or even better
texture than that of the substrate. It was shown that a S c(2x2) sub-layer formed at the metallic
surface as a positive effect on the nucleation. The crystallisation of LZO on Cu55Ni45 still has to be
improved, being inhibited by trapped C in the film. Recent progresses using our continuous
MOCVD system are shown. A CC fabricated by an all MOCVD process has been obtained on
SS/YSZIBAD substrate with high transport critical current (170 A/cm-width, at 77 K). It is also
shown that LZOMOD can efficiently protect Ni5W RABITS from oxidation during deposition of
CeO2 layer by MOCVD under 30-40% O2 partial pressure. This opens the possibility to fabricate a
CC on RABITS by MOCVD. This shows that a mixed MOD/MOCVD approach could be
efficient. Finally a 2m long CC SS/YSZIBAD has been tested for fault current limiter applications.
Best limitation was observed at 86 K where an equivalent energy of 340 J has been dissipated in
the CC during 12 ms without apparent damage of the CC. In a subsequent operation, the CC was
however destroyed. The causes are discussed in the perspective to design better architectures for
this application.
The Microstructure and Mechanical Properties of Mg-8Zn-8Al-4RE Magnesium Alloy
Authors: Wang Jun , Wang Jian Li , Xiao Wen Long , Wu Yao Ming , Wang Li Min
Published: March 2009

The Mg-8Zn-8Al-4RE (RE = mischmetal, mass%) magnesium alloy was prepared by
using casting method. The microstructure and mechanical properties of as-cast alloy, solid solution
alloy and aged alloy samples have been investigated. Optical microscopy, X-ray diffractometery and
scanning electron microscope attached energy spectrometer were used to characterize the
microstructure and phase composition for the alloy. Net shaped τ-Mg32(Al,Zn)49 phase was obtained
at the grain boundary, and needle-like or blocky Al11RE3 phase disperses in grain boundary
and α-Mg matrix. The τ-Mg32(Al,Zn)49 phase disappeared during solution treatment and a new phase
of Al2CeZn2 formed during subsequent age treatment. The mechanical properties were performed by
universal testing machine at room temperature, 150 °C and 200 °C, separately. The ultimate tensile
strength of as-cast alloy is lower compared to an age treatment alloy at 200 °C for 12h. The strengths
decreased with enhancing test temperature, but elongation has not been effect by age treatment.
Continuous Deposition of Buffer Layers for YBCO Coated Conductor Using Reactive Magnetron Sputtering
Authors: Yang Jian , Liu H.Z. , Qu F. , Zhang H. , Zhou Q. , Gu H.W.
Published: March 2009

A reel-to-reel deposition system was set up for studying YBCO coated conductor.
Continuous deposition of multi-layer CeO2/YSZ/Y2O3 buffer layers was carried out on 10mm-width
biaxially textured tape of NiW using the reactive dc magnetron sputtering technique. A continuous
and uniform buffer layer with good texture was presented over length. For 10–meter-long tapes, the
φ-scan FWHM values of Y2O3 (222), YSZ (111), and CeO2 (111) were 7.77°, 7.68° and 7.93°,
respectively. The rocking curves showed that the average FWHM values of Y2O3 (004), YSZ (002),
and CeO2 (002) were 5.02°, 4.67° and 4.44°, respectively. The microstructure and interfaces of buffer
layers were observed by scanning electron microscopy (SEM) and Auger electron spectrum (AES).
YBCO layer was prepared by magnetron sputtering technique as well on the short samples.
Study on the Precursory Powder for Bi-2223 Tape
Authors: Zheng H.L. , Xu X.Y. , Xiong X.M. , Liu G.Q. , Hao Q.B. , Li Cheng Shan , Zhang Ping Xiang , Lu Ya Feng
Published: March 2009

The Phase formation in the precursory powder, the particle size and the homogenization
phase distribution have been investigated in this paper. Size of the powder particle has been reduced
by a ball-milling process. The effects of the ball-milling on the characteristic of the powder have been
studied by XRD. The modality and distribution of 2212, Ca2CuO3 and CuO in the powder were
observed by SEM. Results show that the Ca2CuO3 particle ground was about 200nm in size. The
precursory powder with the non-superconducting phases distributed uniformly in the mixture powder
was obtained for Bi-2223 long tape.
Influence of Sheath Materials on the Strain Tolerance of Bi-2223 Superconducting Tapes
Authors: Huang Xu Qiang , Lu Zhao Yang , He Yan Fa , Sun Jing , Wang Jin Xing
Published: March 2009

The critical current versus tensile strain characteristics of mono- and multi-filament
Bi-2223 tapes with Ag and AgMn and AgMg sheath has been studied. The strain tolerance ε0.9 of
naked mono- and 37-filament Bi-2223 tapes were 0.13% and 0.20%, respectively. Ag sheath
increased the strain tolerance ε0.9 of critical current by 0.08% and 0.16% for mono-filament and
37-filament Bi-2223/Ag tapes. The ε0.9 of Bi-2223 with Ag and AgMn and AgMg sheath increased
with filament number. AgMn and AgMg sheath, increasing ε0.9 of Bi-2223 tapes by 0.07-0.09%, are
effective to improve strain tolerance of critical current for multifilamentary Bi-2223 tapes.
Effect of RE Content on the Fracture Behavior in Mg-Gd-Nd-Zr Alloys
Authors: Zheng Kai Yun , Dong Jie , Zeng Xiao Qin , Ding Wen Jiang
Published: March 2009

Tensile tests were performed on T4-treated specimens of GN62K (Mg-6Gd-2Nd-Zr(wt%))
and GN112K (Mg-11Gd-2Nd-Zr) alloys at room temperature and on T6-treated ones from room
temperature to 300°C. The fracture behavior was investigated by using SEM images of fracture
surfaces together with optical metallographs adjacent to the surface. Quasi-cleavage fracture was
observed in the fracture surfaces of both alloys in T4-treated condition, and it seems that RE content
has no significant effect on the fracture mechanism in T4-treated alloys. As for T6 treated condition,
cracking was in a manner of transgranular cleavage and/or quasi-cleavage fracture in GN62K alloy
but intergranular fracture in GN112K alloy, which implies that the fracture mechanism in T6-treated
Mg-Gd-Nd-Zr alloys can be altered by the amount of RE addition. This phenomenon is interpreted in
association with the relative strength of grain bulk and boundary.
Comparative Studies of Nanoscale SiC Whisker and Si/N/C Doped MgB2 Tapes
Authors: Zhang Xian Ping , Ma Yan Wei , Gao Zhao Shun , Wang Dong Liang , Yu Zheng Guang , Nishijima Gen , Watanabe K. , Guo Jian Dong
Published: March 2009

Fe-sheathed MgB2 tapes were prepared by the in situ powder-in-tube (PIT) technique
using nanoscale Si/N/C and SiC whisker as doping materials, respectively. It is found that the doped
tapes exhibited superior field performance and higher critical current (JC) values than the undoped
tapes in the magnetic field up to 12 T. Moreover, the improvement of JC for the SiC whisker doped
samples was more significantly than that in Si/N/C doped tapes, while flux pinning ability
enhancements were similar. It is proposed that the difference of impurity content in MgB2 matrix,
which affects the grain connectivity, is responsible for JC value difference between Si/N/C and SiC
whisker doped samples.
Solution Phase Synthesis of Superconducting La2CuO4 Microspheres
Authors: Zhang G.Q. , Lu X.L. , Qu J.F. , Wang Wei , Li Guang , Li X.G.
Published: March 2009

In order to exploit new strategies for fabricating high-temperature superconductors with
special morphologies and investigate the effects on their superconductivity, we successfully utilized a
facile polyol process for fabricating a large amount of La2CuO4 (LCO) microspheres using
La(CH3COO)3·1.5H2O and Cu(CH3COO)2·H2O as raw materials and ethylene glycol as both complex
agent and solvent. The well crystallized LCO microspheres can be obtained by annealing the
La-Cu-complex precipitation formed after refluxing process at 750 oC for 10 hours. Field-emission
scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) results
indicated that the as-prepared sample had an average diameter of about 800 nm. The powder X-ray
diffraction (XRD) patterns showed that the LCO microspheres were of pure phase. The magnetization
measurement of the sample annealed at 900 oC in pure oxygen for 20 hours showed that the
superconducting transition temperature (Tc) of the LCO microspheres was about 38 K, which in
agreement with that of bulk counterparts.
Analysis on the Ceasing Mechanism of the YBCO Crystal Growth during Melting Growth Process by Unidirectional Solidification
Authors: Cao Hai Tao , Hu Rui , Kou Hong Chao , Li Jin Shan , Gao En Zhi , Fu Heng Zhi , Zhou Lian
Published: March 2009

The unidirectional solidification technology by a zone melting method was performed to
obtain the large single domain YBCO. The interface morphology and chemical composition at the
growth front of the YBCO crystal were investigated in order to make clear the growth characteristic of
the YBCO crystal during melting growth by unidirectional solidification. It was found that YBCO
crystal would cease growing when yttrium was depleted in the liquid phase at the YBCO crystal
growth front. For maintaining the continuous growth of YBCO crystal, compositions of Y, Ba and Cu
in raw samples have to be adjusted so as to make yttrium rich in the liquid phase at the YBCO crystal
growth front during the melting growth process. It is very useful for the study on the mechanism of the
YBCO crystal growth.
Ionic Cluster Effect in Suppression on Superconductivity in Doped Y123
Authors: Li Ping Lin , Wang Ai Hua , Tian Yong Tao , Wang Xiao Xia , Ji Yong , Zhang Yi Min , Gao Li Ming , Zhang Jie
Published: March 2009

Positron annihilation technology and simulation analyses are used to investigate the doped
YBCO. The results suggest that Co ionic cluster effect is stronger than Al in YBCO. The cluster effect
not only causes the local electron density to reach the saturation, but also suppresses the
superconductivity significantly.
Microstructure and Pseudoelasticity of Ti-Nb-Si Based Alloys with Biocompatible Alloying Elements
Authors: Kim Won Yong
Published: March 2009

We have newly designed a metastable β Ti-Nb-Si based alloy with biocompatible alloying
elements without containing toxic V or Al for orthodontic applications. Microstructures and
pseudoelastic behavior of β Ti-Nb-Si alloys were investigated in order to correlate the
pseudoelasticity and microstructure together with martensite transformation. Nb and Si alloying to the
present alloy make β phase to be stable. It is found that metastable β phase is favorable to display
pseudoelastic behavior than stable or unstable β phase. Optical microscope (OM) revealed that
stress-induced martensitic transformation takes place during room temperature deformation in the
present alloys. Within the alloys having β (bcc) phase studied the alloy with low content of Si
appeared to exhibit a dominant behavior for stress-induced martensitic transformation than that with
high content of Si. After recrystallization heat treatment pseudoelasticity of the present alloy appeared
to be prominent. The pseudoelastic behavior of this alloy was correlated to the stress-induced
martensite transformation. Pseudoelasticity of the present alloys is hindered by the development of
{001}<110> rotated cube component.
Preparation of FeCoZrBCu Thin Films and their Effect of Microstructure on Magnetic Properties
Authors: Cui Jia Ping , Zhong Li , Bi Xiao Fang
Published: March 2009

In this work, (Fe,Co)–Zr–B–Cu films have been deposited on glass and Si substrates by
DC magnetron sputtering method. X-ray diffraction analysis was used to identify the structure of the
films. A transmission electron microscope (TEM) was employed to observe the microstructure for the
films. Magnetic properties at room temperature were investigated by a Vibrating Sample
Magnetometer (VSM). It was obtained that the as-deposited films on glass and Si substrates were in
an amorphous state. In addition, it has been found that the coercivity is dependent on film thicknesses.
Sintering of β-Si3N4 Powder Prepared by Self-Propagating High-Temperature Synthesis (SHS)
Authors: Bai Ling , Zhao Xing Yu , Ge Chang Chun
Published: March 2009

Sintering of the Self-Propagating High-Temperature Synthesis (SHS) of β-Si3N4 powder
with 6.67 wt.% Y2O3 and 3.33 wt.% Al2O3 as sintering additives has been emphatically investigated
using hot-press sintering process. The relative density of hot-pressed β-Si3N4 reached near to the
full densification (99.43%) at 1700°C. The similar micrographs with self-reinforcing rod-like
β-Si3N4 grains forming an interlocking structure were observed. The better mechanical properties of
hot-pressed Si3N4, such as the hardness (16.73GPa), fracture toughness (5.72 MPa·m1/2) and
bending strength (611.72MPa) values, were obtained at 1700°C. The results indicate that good
sinter ability can be obtained with the cheaply SHS of silicon nitride powder for preparing silicon
nitride materials, which will make the cost of silicon nitride materials lowered.
Magnetostriction and Hysteresis of (Tb,Dy,Ho)Fe2 Alloys
Authors: Zhang Hong Bo , Jiang Cheng Bao
Published: March 2009

The Tb/Dy ratio of Tb0.30Dy0.70Fe1.95 giant magnetostrictive alloy was shifted away from
0.30/0.70 to 0.36/0.64 to enlarge the operating temperature range. However, the magnetostriction was
reduced under low magnetic field and its hysteresis was enlarged with the shift of Tb/Dy ratio. Ho
addition improves the magnetostriction under low magnetic field and reduces the hysteresis of
TbxDyyHozFe1.95 (x+y+z=1). The crystal structure, lattice constant, Curie temperature, spin
reorientation temperature, magnetization, magnetic anisotropy and magnetostriction of
TbxDyyHozFe1.95 alloys were investigated. X-ray diffraction patterns demonstrate that all the samples
possess MgCu2-type cubic Laves structure. The lattice parameter, Curie temperature and magnetic
anisotropy constant K1 decreased with increasing Ho concentration. The hysteresis represented by the
width of magnetostriction versus the applied field was reduced due to the addition of Ho. At a
compressive stress of 10 MPa and a magnetic field of 1000Oe, the addition of Ho to the ternary
TbxDyyFe1.95 compound reduced the width of magnetostriction by 25% for Tb0.296Dy0.472Ho0.232Fe1.95
and by 27% for Tb0.296Dy0.472Ho0.232Fe1.95 compared to the Tb0.36Dy0.64Fe1.95 alloy, while the strains
were reduced by only 3% and 9%.
The Growth Mechanism of Quasi One-Dimensional ZnO Nanostructures Synthesized by Carbon Reduction without Catalyst
Authors: Liu W.C. , Cai Wei
Published: March 2009

In order to obtain quasi one-dimensional nanostructures, various methods have been
developed for the preparation and many mechanisms have been put forward such as VS (vapor-solid),
VLS (vapor-liquid-solid), SLS (solid-liquid-solid), and so on. In present study, the zinc oxide
one-dimensional nanostructures synthesized by carbon reduction route without catalyst isn’t
controlled by the conventional VLS mechanism because that there is no droplet at the growth end of
the nanostructures. By using a variety of growth times and the ratios of the zinc oxide and the
activated carbon, it can be deduced that the liquid zinc island formed firstly and then the ZnO
nanostructures growth on them. The morphologies and microstructures of samples were characterized
by scanning electron microscope (SEM) observations, X-ray diffraction (XRD) analysis, transmission
electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The structure
characterization confirms that all the grown one-dimensional materials are hexagonal wurtzite ZnO.
A Constitutive Model for Casting Magnesium Alloy Based on the Analysis of a Spherical Void Model
Authors: Chen Bin , Peng X. , Zeng Xiang Guo , Wu X. , Chen S.
Published: March 2009

Casting magnesium alloys are heterogeneous materials containing numerous voids.
Assuming the voids are spherical, in the present investigation, the evolution equations of the growth
and nucleation of the voids have been presented. Combining the evolution equation of the void
growth with that of the void nucleation, the evolution rule of the voids was obtained. Based on the
void evolution rule a nonclassical elastoplastic constitutive model involving void evolution was
developed. The corresponding numerical algorithm and finite element procedure were developed and
applied to the analyses of the elastoplastic response and the porosity of casting magnesium alloy. The
calculated results show the satisfactory agreement with experiments.
Effects of Annealing on Phase Transformation and Mechanical Behaviors of NiTi Shape Memory Alloy Ultra Thin Sheet
Authors: Meng Ling Jie , Li Yan , Zhao Xin Qing , Xu Hui Bin
Published: March 2009

The phase transformation and mechanical behaviors of cold-rolled NiTi shape memory
alloys ultra-thin sheet with 100μm in thickness are investigated. The transformation behaviors of
the NiTi sheet are found to be remarkably influenced by heat treatment using electric resistance vs.
temperature measurements. The martensitic transformation temperature reduced by annealing at
400°C or 600°C, and R-phase transformation appears when annealing at 400°C. The martensitic
reorientation occurs when the NiTi sheets annealed at 400°C is deformed at room temperature and
the maximum shape memory strain is 3.5% at 100% recovery ratio. For the NiTi sheets annealed at
600°C, a superelastic strain of 5% and a transformation stress about 500MPa are achieved.
Hot Corrosion Behavior of AlCuFeCr Quasicrystalline Coating on Titanium Alloy with the Mixture of NaCl and Na2SO4 Deposit
Authors: Wang Feng Feng , Zhou Chungen , Gong Sheng Kai , Xu Hui Bin
Published: March 2009

The hot corrosion behavior of titanium alloy and AlCuFeCr quasicrystalline coating on
titanium alloy in the presence of a solid mixture of NaCl and Na2SO4 deposit at 700°C was studied.
The result shows that weight-gain kinetics for titanium alloy exhibited a linear rate law, while the
kinetics of AlCuFeCr quasicrystalline coating displayed parabolic growth rate. The corrosion
resistance of the titanium alloy was improved by applying the AlCuFeCr quasicrystalline coating. The
corrosive oxide morphology formed on titanium alloy was porous. For AlCuFeCr quasicrystalline
coating with the mixture of NaCl and Na2SO4 deposit, the scale formed on the coating surface was
compact and uniform. Oxide formed on the surfaces of Al-Cu-Fe-Cr quasicrystalline coatings after
hot corrosion consisted of Al2O3.
Microstructures, Tensile Properties and Forming Process of AZ31 Alloy Sheets
Authors: Yan Yun Qi , Zhang H. , Chen Q. , Zhong H. , Weng W.P.
Published: March 2009

Rolling and punching techniques of AZ31 alloy were investigated in this paper. Various
rolling experiments were carried out to make fine-grained Mg sheets. Punching tests were conducted
at the temperatures range from 70 to 300 oC. The analysis revealed that there existed an excellent
warm forming temperature for as-rolled AZ31 alloy. A warm deep punching tool setup using heating
elements was designed and manufactured to produce the cell phone. Microstructures were observed
using optical and scanning electron microscope equipped with EBSD. The textures in as-rolled and
as-annealed specimens attribute to different mechanical properties along the various direction.
Effect of Temperature on Microstructure and Texture during Compression of AZ31
Authors: Jiang J. , Godfrey Andrew , Liu Qing
Published: March 2009

The hexagonal crystal structure of AZ31 results in a very high mechanical anisotropy and a
poor formability of this alloy. In order to address these problems the influence of twinning, slip and
dynamic recrystallization (DRX) on the microstructure and texture evolution during compression of
AZ31 has been studied over a range of temperatures. Cylindrical samples were tested uniaxially in
compression from room temperature to 350oC, with the compression axis parallel to either the normal
direction (ND) or the transverse direction (TD) of the hot-rolled sheet from which the samples were
cut. The microstructure was characterized using electron backscattered diffraction (EBSD) analysis.
Extensive twinning was only observed in the TD samples at all temperatures. The effect of the
difference in twinning and slip between the TD and ND samples on the mechanism of dynamic
recrystallization has also been investigated. For this, the grains formed during DRX were identified by
their appearance in EBSD orientation maps and the orientations of these grains determined.
Thermo-Mechanical Coupled Simulation of Warm Stamping of AZ31 Magnesium Alloy Sheet
Authors: Li Da Yong , Chang Qun Feng , Peng Ying Hong , Zeng Xiao Qin
Published: March 2009

Uniaxial tensile test of a cross rolled magnesium alloy sheet was conducted under different
temperatures and strain rates. The mechanical propriety of AZ31 magnesium alloy sheet was
analyzed according to the true strain-stress curves. Then the non-thermal drawing process, during
which the temperature of die, blankholder and blank is 200°C while the punch is kept at room
temperature, was simulated by the thermo-mechanical coupled finite element method. The
deformation behavior and the temperature change in the drawing process was investigated. Due to the
heat conduction, there was non-uniform distribution of temperature along flange area, force transfer
area and deformation area. Therefore the resistance of the force transfer area is enhanced and the
warm formability of magnesium alloy sheet can be further improved. The thermo-mechanical
coupled simulation provides a good guide for the development of non-isothermal drawing
techniques.
Mechanical Properties of Mg-8Zn-4Al-xCa Extruded Magnesium Alloy Tube at Elevated Temperature
Authors: Yu Bao Yi , Li Yu Ying , Song Hong Wu , Yuan Xiao Guang , Liu Zhen
Published: March 2009

Microstructures and tensile properties of Mg-8Zn-4Al-xCax=0.6wt.%, 1.0wt.%, 1.3wt.%,
named as alloy 1#, 2# and 3# , respectively)extruded magnesium alloy tube were studied at room and
elevated temperature. The results show that Ca can increase tensile strength of the alloy at 150 and
200°C significantly. At the temperature of 200°C, alloy 3# achieved optimal tensile properties, of
which the ultimate tensile strength, the yield strength and the elongation were 165.8MPa, 108.7Mpa
and 41.5% respectively. Compared with the properties of as cast ZAC8506 Magnesium alloy, it is
shown that the tensile properties of alloy 3# are much higher than that of ZAC8506 at both room
temperature and 150°C. Alloy 3# also gets better tensile performance than AZ91D extruded tube
produced in the same way at the temperature of 200°C Mg2Al3 and Ca2Mg5Zn13 phases are found in
the microstructure which should contribute to the higher performance of alloy 3# at elevated
temperature
Development and Validation of Extrusion Limit Diagram for AZ31 and AM30 Magnesium Alloys
Authors: Wang Ying Xin , Zeng Xiao Qin , Ding Wen Jiang , Luo Alan A. , Sachdev Anil K.
Published: March 2009

Uniaxial hot compression tests were performed at constant temperature (T) and strain rate
(ε& ) in the ranges of 200-500 °C at an interval of 50 °C and 0.001-20 s-1. The flow stress data were
used to develop the extrusion limit diagram for AZ31 and AM30 magnesium tubes. The extrusion
limit diagram shows a wide region available for extruding AZ31 and AM30 seamless tubes, and
comparison of the two extrusion limit diagrams shows that, the extrudability of AM30 alloy is better
than that of AZ31 alloy. Actual extrusion trials validated the predicted temperature rise limit curve
corresponding to the occurrence of surface cracking during the extrusion process. Magnesium tubes
were successfully extruded according to the safe regions identified by the extrusion limit diagram.
Effect of Temperature and Relative Humidity on Fatigue Crack Propagation Behavior of AZ61 Magnesium Alloy
Authors: Zeng Rong Chang , Han En-Hou , Ke Wei
Published: March 2009

The fatigue crack propagation (FCP) behavior of magnesium alloy AZ61 at room
temperature (RT), elevated temperature (60°C, 120°C) , and in ambient and wet air was investimated.
The mechanisms of FCP were discussed in detail. It was demonstrated that The FCP rate of AZ61
magnesium alloy increased with increasing temperature and relative humidity (RH). Obvious change
in the microstructure occurred during fatigue at elevated temperature, particularly at 120°C, compared
to its original microstructure. Grain growth, deformation twin, grain boundary (GB) immigration and
precipitates were observed in the microstructure at 120°C after fatigue. A bend occurred in the curves
of FCP rate versus stress intensity factor at 120°C, which corresponded to a transition of failure mode
from a mixed intergranular and transgranular fracture to a transgranular fracture. At first stage, the
FCP rate increased sharply, and then went up slowly due to the growth of grain size. Secondary phase
particles facilitated the fatigue crack initiation. The Hydrogen embrittlement (HE) may be primarily
responsible for accelerating FCP rate in wet air.
The Thermodynamics Calculation of Mg-Zn Alloy
Authors: Liu Tian Mo , Zhou Hong Yi , Pan Fu Sheng
Published: March 2009

In the present work Miedema model has been developed, and the formation enthalpy of
Mg-Zn alloys and the activity curve of Zn in Mg-Zn alloy at 1000K have been calculated according to
the Miedema model. The calculation results showed that the formation enthalpy of Mg-Zn was small,
and the excess entropy attributes a lot to the result. When excess enthopy was considered, the
calculation results were found to be in good agreement with the experimental values.
Intermediate Phase Growth of Mg-Al Diffusion Couple under a Strong Static Magnetic Field
Authors: Dong Jie , Li Z.F. , Zeng Xiao Qin , Ding Wen Jiang
Published: March 2009

Intermediate phase growth in Mg-Al diffusion couples were studied with different intensity
of a strong static magnetic field from 0 to 10 Tesla. Thickness measurement of the intermediate
phases (Mg17Al12 and Al3Mg2) shows that with the increasing of magnetic field intensity, the growth
rate of both intermediate phases is retarded. The decrease of the phase growth rate is ascribed to the
suppressed Al, Mg atom interdiffusion in the diffusion couple under the static magnetic field. It is also
found that the orientation relationship between couple interface and magnetic field direction has no
influence on the growth of intermediate phases.
Effect of CeCl3-Containing Flux on Microstructure and Mechanical Properties of Mg Alloy Containing Rare Earth
Authors: Ding Wen Jiang , Wu Guo Hua , You Bong Sun , Chang Dong Yim
Published: March 2009

The effects of CeCl3-containing fluxes on RE element loss, the high temperature
mechanical properties, microstructure and corrosion properties of magnesium alloy containing RE
have been studied. The results showed that a certain amount of CeCl3 in purification fluxes restrained
the reaction between the Ce element and fluxes to decrease the loss of Ce in alloys. With the flux
containing 9% CeCl3, the loss rate of alloy element Ce can be reduced from 26.9% to 3.4%, and the σb
and δ of the alloys at 150°C counld be improved from 160.9MPa and 6.2% to 176.5MPa and 7.9%
compared with that of conventional MgCl2-containing flux , respectively. Besides, the coarse β phase
and rod-like RE phase were refined effectively by CeCl3-containing fluxes.
Zn Coatings on AZ91D Magnesium Alloy Prepared by Electroplating from the Electrolyte Containing SnO2 sol
Authors: Li Wei Ping , Zhu Li Qun , Li Meng
Published: March 2009

A new method has been devised to obtain a Zn coating on the AZ91D magnesium alloy
from the base electrolyte of ZnSO4 and K4P2O7 by electroplating. To improve the properties of the
coating, a SnO2 sol was prepared and added in the electrolyte. The effects of the SnO2 sol addition on
the morphologies, compositions and phase structures of the plated coatings were investigated by
scanning electron microscopy (SEM), energy dispersion spectrometry (EDS) and X-ray diffraction
(XRD). The results reveal that the addition of SnO2 in the solution changes the polarization behavior
of the electrolyte and the compositions of the plated coating. The plated coating formed in the
electrolyte with an addition of SnO2 sol are more uniform and provide a better protection for the
AZ91D substrate.
Effect of Si on As-Cast Microstructure in Quasicrystalline Al-Cu -Fe Alloy
Authors: Zhang Jin Shan , Xue Yong Jun , Guo You Jun , Xu Chun Xiang , Liang Wei
Published: March 2009

Effect of Si on the forming ability of quasicrystalline phase in Al65Cu20Fe15 alloys
fabricated under conventional casting conditions has been studied using X-ray diffraction (XRD),
optical microscopy (OM), and scanning electron microscopy (SEM). The results show that under the
conventional casting conditions, it is found that the addition of certain amount of Si into the Al-Cu-Fe
melts can change the formation of Al62.5Cu25Fe12.5 quasicrystals during the solidification process.
Compared with Al65Cu20Fe15 alloy, Al64.5Cu20Fe15Si0.5 alloy has smaller volume fraction of β phase
solidifying initially, larger volume fraction of the quasicrystal phase generating in the subsequent
peritectic reaction, and larger volume fraction of ω phase solidifying finally. Both experimental
results and the theory of Hume-Rothery show that addition of Si can promote the formation ability of
the icosahedral quasicrystalline Al62.5Cu25Fe12.5 phase in Al-Cu-Fe alloy.
Application of Microstructure Sensitive Design to FCC Polycrystals
Authors: Duvvuru Hari K. , Knezevic Marko , Mishra Raja K. , Kalidindi Surya R.
Published: March 2009

Microstructure Sensitive Design (MSD) offers a rigorous mathematical framework for
representing the relevant statistical details of the material microstructure for a given design problem,
and for developing quantitative invertible relationships between these microstructure representations
and the macroscale properties of interest. The methodology makes extensive use of Fourier
representations of the distribution functions representing the material internal structure and existing
homogenization theories. In this paper, we describe the application of the MSD framework to fcc
polycrystals with a specific focus on the crystallographic texture as the microstructure design
variable. The advantages of the MSD approach are demonstrated through a number of elastic-plastic
property closures for cubic metals.
Coating Effect on Increasing Mechanical Property of 6061-T651 Alloy by Laser Shock Processing
Authors: Zhang Yong Kang , Ren Xu Dong , Zhou Jian Zhong , Feng Ai Xin
Published: March 2009

Laser shock processing (LSP) employs high-energy laser pulses from a solid-state laser to
create intense shock waves into a material, which can induce compressive residual stresses in the
target surface and improve its mechanical property efficiency. Three different ablative, sacrificial
coating were chosen to protect the 6061-T651 alloys from surface melting by laser pulse. This paper
analyzes the effect of the paint and foil coatings on the shock wave propagation into the 6061-T651
alloys and the resulting change in mechanical properties. The depths of hardening by laser processing
of 6061-T651 alloys up to 1 mm, and the surface hardness reach to 138HV. When the laser pulse
energy density increase from 2.8 GW/cm2 to 3.6 GW/cm2, the surface hardness of the black paint,
aluminum foil and silica acid black paint samples increase to 19, 27, 36 respectively.