bluuebunny/crossref_metadata_2025 huggingface dataset:
Influences of Argon Atmosphere on Ceramic Coatings on Ti–6Al–4V Alloy by Micro-Plasma Oxidation in Different Solutions
Authors: Hao Guo Dong , Jiang Zhao Hua , Wu Xiao Hong , Cao Yan Hua
Published: March 2009

Compound ceramic coatings were prepared on Ti-6Al-4V allosy by pulsed bi-polar
Micro-plasma Oxidation (MPO) in NaAlO2(S1) and Na2SiO3(S2) solution respectively. The coated
samples were calcined in argon under 1000 oC. The phase composition,morphology and element
content of the ceramic coatings were investigated by XRD, SEM and XRF. After oxidation in argon,
The Al2TiO5 of S1 coating surface was decomposed into Al2O3. SiO2 was crystalized in S2 coating
with the final proportion of SiO2 to TiO2 on the coating surface is 81:18. The morphology of the
ceramic coatings after the calcination was also different. S1 coatings calcined in argon were fine,
grains and pores were smaller and were combined tightly with the substrate, on the contrary, S2
coatings calcined in argon cracked on the coating surface and were separated with the substrate. The
content of elements in the coatings both changed a little, which may be due to the reaction of the
substrate in the oxidation. According to the phase composition and the morphology of the coatings,
S1 coatings are better than S2 coatings.
Influence of Cooling Rates on the Dentrite Morphology and Hardness of the Surface-Chilled Mg-10Gd-3Y Magnesium Alloy
Authors: Zhou Yang , Peng Li Ming , Wang Qu Dong , Lin Jin Bao , Ding Wen Jiang
Published: March 2009

Mg-10wt%Gd-3wt%Y alloy was cast in a step-like mould, which provided five different
cooling rates. The dentrite morphology and hardness of the as-cast alloy from the surface to the center
was investigated and the influence of the cooling rates on these was analyzed. It was indicated that
there were two different trends for the hardness distribution: in the section of the step castings with
the two slowest cooling rates, the hardness decreased with the increase of depth; while in the other
three step castings the hardness increased with the increase of depth. Also it was founded that the
hardness could be influenced by the grain boundary, dentrite morphology and dentrite arm spacing
(DAS) in the alloy. At last, according to the standard deviation curves of the hardness, the chilled
depths were about 5mm in 1st step and 10mm in 2nd step. And the other steps were fully chilled.
The Effects of Rare Earth Elements on Corrosion Resistance of Sol-Gel Coatings for 2024 Aluminum Alloy
Authors: Xu Yue , Li Ying Jie , Li Sha
Published: March 2009

Rare-earth modified coatings on 2024 aluminum alloy were prepared by sol-gel methods,
aiming at improving the corrosion resistance with the environmental friendly features. The
investigation put emphases on the effects of rare-earth additives on corrosion resistance and
microstructure of sol-gel coatings. The results revealed that coated samples containing 2g·L-1
rare-earth not only delayed the incubation period of corrosion, but also hindered the development of
it, and their corrosion rate decreased 80.3% compared with the bare ones and was 15.9% than the
rare-earth free coated ones. The action of rare-earth on morphology and microstructure of sol-gel
coatings for 2024 Al alloy was studied by SEM. High density good cohesion, and intact coverage
were showed clearly ,which provided a reliable proof of the reformative effects of rare-earth
additives.
High-Strength Nb3Sn Wire Development for Compact Superconducting Magnets
Authors: Watanabe K. , Awaji Satoshi , Nishijima Gen
Published: March 2009

A superconducting magnet with a magnetic energy of E = B2/2μo [J/m3] has to overcome
a magnetic force of P = B2/2μo [Pa] in the same expression. This means that a high-field 20 T
superconducting magnet produces an electromagnetic force of 160 MPa. In order to stand such a large
force, Nb3Sn superconducting wires are usually reinforced by the hard-copper housing as an external
reinforcement method or the stainless steel winding as a mechanical backup of an outermost Nb3Sn
coil. If we focus on a compact superconducting magnet like a cryocooled superconducting magnet, a
high-strength superconducting wire with a small diameter size of 1- 2 mm is required. The High-Field
Laboratory for Superconducting Materials, IMR, Tohoku University has developed Nb3Sn wires
internally reinforced with CuNb or CuNbTi composite. These high-strength Nb3Sn wires were
successfully employed to construct the unique compact cryocooled 28 T hybrid magnet and the
cryocooled 18 T high-temperature superconducting magnet. In addition, we found that the prebending
effect for high-strength Nb3Sn wires outstandingly improves the Tc, Bc2 and Ic properties. As a next
step, we intend to develop new Nb3Sn strand cables with the strong mechanical property of 500 MPa,
applying the prebending effect for a future 22 T-φ400 mm room temperature bore superconducting
magnet of a 50 T-class hybrid magnet.
Finite Element Analysis of Quench Propagation Velocity in Bi-2223/Ag Superconducting Multifilamentary Tape
Authors: Wu Chun Li , Yang Hai Liang
Published: March 2009

Quench propagation velocity is an important parameter to the stability and protection
issues of superconducting magnet. In this paper, the finite element method (FEM) numerical
simulation of quench propagation velocity has been performed for using the powerful analysis
software COSMOS by establishing a suitable thermal analysis model of Bi-2223/Ag superconducting
multifilamentary tape. The effects of quench energy and operating temperature on the quench
propagation velocity have been studied. The analysis shows that the simulation result basically
coincides with the experimental result.
High Magnetic Field Superconducting Magnet Technology and its Applications
Authors: Wang Qiu Liang , Dai Y. , Song S. , Lei Y. , Zhao B. , Wang H. , He C. , Wang Hui , Yan Lu Guang , Lin L.
Published: March 2009

High magnetic field superconducting magnet technology has been developed in the recent
years for all kinds of special applications in China. In the paper, the successful development of high
magnetic field superconducting magnet technology is presented.
The Progress on Study of Isotope Effects in High TC Copper Oxide Superconductors
Authors: Chen Yu , Huang Xin Min , Wang Jian Wu , Zeng Xiao Shan
Published: March 2009

Through the review of the correlation on the isotope effects research and superconductivity
mechanism research as well as the progress on the study of the isotope effects in the high Tc copper
oxide superconductors, we have found the fundamental factors that cause the different changes of the
isotope effect value in different dope region in high Tc cupper oxide superconductors. We point the
high-temperature superconductivity mechanism possible origin phonons mediation electrons.
HTS High Q Resonant Controller
Authors: Jin Jian Xun , Zhang Chang Ming , Guo You Guang , Zhu Jian Guo
Published: March 2009

High Tc superconductor (HTS) technology has been used to develop an advanced high Q
resonant circuit and its devices. With a HTS, a very high Q circuit can be achieved; consequently
special aspects such as high voltage generation and high current control can be theoretically and
practically realized. Theoretical study has been carried out, as well as a practical approach has been
made for the concept verification. This paper describes the theory of this high Q resonant circuit and
the operational principle of its high voltage generation and current control.
Te Substitution Effect in Low-Dimensional Superconductor NbSe2-xTex (x = 0, 0.1, 0.2)
Authors: Ahmed Ejaz , Li Lin Jun , He Cheng , Wang Hong Tao , Shen Jing Qin , Xu Zhuan
Published: March 2009

The Te doped NbSe2-xTex (x=0, 0.10, 0.20) single crystals were prepared by vapor
transport method and the variations of structure and superconducting properties with Te content were
studied. It is found that the Te substitution increases the degree of disorder and causes sharp decrease
of superconducting transition temperature (Tc). The temperature dependence of upper critical field
(Hc2) of pure NbSe2 crystal can be fitted by the two-band model, and the effect of Te substitution on
Hc2(T) is discussed.
Effects of Heat Treatments on the Nb3Sn Composite Strands
Authors: Liang M. , Zhang Ping Xiang , Tang X.D. , Li J.S. , Li C.G. , Li K. , Yang M. , Xiao C.J. , Zhou Lian
Published: March 2009

Nb3Sn superconductors are widely used in high magnetic field application. Internal tin
processed Nb3Sn wires used for ITER coils (at 4.2K, 12T) were heated by two steps, local heat
treatment and reaction heat treatments. The superconducting properties of Nb3Sn were investigated as
a function of reaction heat treatment (HT) for strands during 625°C~665°C.To study the heat
treatment effects on Jcn and n-value of Nb3Sn strands, different HT-parameters, i.e., annealing
temperature and times, were applied on the Nb3Sn multifilament strands.
Influence of Preparation Process on Microstructure, Critical Current Density and Tc of MgB2/Fe/Cu Wires
Authors: Wu Y.F. , Yan G. , Li J.S. , Feng Y. , Chen Shao Kai , Tang Hui Ping , Xu H.L. , Li Cheng Shan , Zhang Ping Xiang , Lu Ya Feng
Published: March 2009

The powder-in-tube MgB2 wires were prepared by high energy milling of Mg and B
powder. The powder was not mechanically alloyed for 2h short milling time. However, the MgB2
grains in wires were very small (20~100nm) and resemble the dimple after post-heat treatment. The
clear evidence for transcrystlline fracture was observed. It indicated that the grain connection was
greatly improved and the fluxing pinning was significantly enhanced. Another point to view was no
intermediate annealing during the whole rolling process. The influence of the post-heat treatment on
the transport current density was studied. Despite the lower Tc of about 35K, the transport current
density reached to 3×104A/cm2 at 15K and 3.5T for wires sintered at 700°C.
Improvements on the Properties of the In Situ MgB2/Fe Tapes Annealed by Spark Plasma Sintering Technique
Authors: Ma Lin , Suo Hongli , Wang Ying , Ma Hong Xia , Liu Min , Li Ya Ming , Zhao Yue , Zhang Zi Li , Zhou Mei Ling
Published: March 2009

In-situ MgB2/Fe tapes were fabricated by the powder in tube (PIT) technology using Mg
and B powders. The tapes were sintered by both an advanced spark plasma sintering (SPS) and a
conventional vacuum furnace, respectively. The effects of these two sintering routes on the
properties of the MgB2 tapes were investigated by the analysis of XRD, SEM and the magnetic Jc
measurements. It was shown that at 10K, 0T, the magnetic Jc value of the tape sintered using SPS
machine at 800°C for 15min under 30MPa were close to 106A/cm2, which was higher than that of
the tapes annealed at 700°C for 2h under pressureless vacuum condition. It was found that the
density and the homogeneity of the MgB2 core were strongly improved using SPS sintering process,
which explained why the MgB2 tapes sintered by SPS method have a higher Jc value. Further
enhancement of Jc in the tapes is expected for the understanding of the SPS sintering mechanism.
Effect of Pulsed Magnetic Field Processing on MgB2 Superconductors
Authors: Li W.X. , Li Ying , Zhu M.Y. , Chen R.H. , Jin H.M. , Dou S.X. , Qin M.J. , Xu X.
Published: March 2009

Pulsed magnetic field was first employed in the study on MgB2 superconductors.
Superconductivity properties and microstructures of Zn and SiC doped MgB2 were discussed in this
paper. The superconductors showed different superconductivities after magnetic sintering. Critical
current density and flux pinning force were relevant to the dopants properties in MgB2. Grains in
the pulsed magnetic processed MgB2 matrix were smaller than those in the normal processed one.
The refinement microstructures have caused the critical current density (Jc) anisotropy in both the
Zn and SiC doped MgB2.
Crystal Growth Mechanism of YBCO Superconductors Prepared by Unidirectional Solidification Method
Authors: Gao En Zhi , Li Jin Shan , Hu Rui , Kou Hong Chao , Cao Hai Tao , Zhang Ping Xiang , Zhou Lian
Published: March 2009

Y123 and Y211 powders were synthesized by solid-state reaction method. YBCO
superconductor specimens were prepared by unidirectional solidification technique. The
microstructure and the structural characteristics were observed by means of the optical microscope,
X-ray diffraction (XRD), scanning electron microscope (SEM). The results showed that the specimen
have a highly aligned structure, it was observed obvious laminated structure of Y123 crystal. Crystal
growth mechanism of YBCO was investigated. Jackson's factor of Y123 crystal was calculated.
Interface form was judged tentatively theoretically. The specimen was rapidly quenched by quick
pulling. Solid/liquid interface structure was observed. It was concluded that a-b plane was faceted
grow forms and layer growing along c-axial on a-b plane.
Effect of Magnet Moving Speed on the Relaxation Rate of the Levitation Force for YBCO Bulk
Authors: Wu X.L. , Yang W.M. , Zhu S.H. , Guo J.Z. , Lu T.N. , Pei J.L.
Published: March 2009

The effect of magnet moving speed on the relaxation of the maximum levitation force of
YBCO bulk has been investigated. The experiment was carried out between a cylinder permanent
magnet and a single-domain YBCO bulk, and the levitation force was measured using a self-made
levitation force measurement system. It is found that the levitation force decreases with time after the
gap distance between the magnet and YBCO bulk reduced to 2 mm and kept for the test. It is also
found that the levitation force and its relaxation rate is different for different moving speed between
the magnet and the YBCO bulk, and the higher the moving speed, the greater the relaxation rate of
levitation force. However, the largest levitation force is obtained at an optimal speed, the higher the
levitation force, and the faster the relaxation of levitation force.
Basic Analysis of Magnetic Field in High Temperature Bulk Superconductors
Authors: Yang Jian Qing , Chen G.D. , Yuan Xiao Yang , Zhu You Zhang
Published: March 2009

The analysis of magnetic field in high temperature bulk superconductors is presented in this
paper. The macroscopic field equations were constructed on the basis of the critical state model and
levitation forces ware analyzed between permanent magnets (PM) and HTSC using analytical method.
The levitation force between permanent magnets (PM) and HTSC calculation were obtained by using
Lorentz force equation [1]. The analytical results show that the presented method is comparatively
accurate by comparing the measured levitation forces and the calculation ones. Some relations
between B(r, t) and levitation force’s hysteresis are investigated.
Low-Temperature Sintering and Dielectric Properties of (Zn1-xMgx)TiO3
Authors: Liu Xiangchun , Gao Feng , Zhao Ming , Tian Chang Sheng
Published: March 2009

The dielectric ceramics comprised of (Zn1-xMgx)TiO3 (x=0.1~0.5, abbreviated to ZMT)
were developed by conventional mixed-oxide method combined with a semi-chemical processing.
V2O5 was used as sintering aids to lower the sintering temperature of ceramics. The results showed
that the hexagonal phase stability region extended from 900 to 1150°C as the amount of magnesium
increased. The densification temperature of ZMT ceramics could be reduced from 1200 to 875°C by
V2O5 additions and using semi-chemical processing, the relative density of ZMT ceramics with
1.00wt% V2O5 addition reach 95% at 875°C. The dielectric properties of ZMT were measured at
different frequencies and the results showed that there existed a decreasing tendency of the loss
tangents (tg δ) with increasing measuring frequency. It is concluded that εr=22 and tg δ= 5.7×10-4 can
be obtained for ZMT ceramics at sintering temperature 875°C.
Comparative Study of Recovery Strains in Severely Cold-Deformed NiTi
Authors: Li Jun Tao , Zheng Yan Jun , Cui Li Shan
Published: March 2009

The recovery strain in the near-equiatomic, severely cold-deformed NiTi, has been
investigated through the study of thermal expansion by employing dilatometer (DL). By designing the
shape of the original surface curve, macroscopic domains with different dislocation density were
introduced into the NiTi alloys and materials possessing the characteristics of composites were
obtained. Results show that in-situ composites of NiTi alloys rendered a distinct recovery strain of
shape memory compared to directly cold-deformed NiTi alloys. We presume that the interactions
between the dislocation texture and martensite variants are introduced when the NiTi martensite is
cold rolled at room temperature might be responsible to the phenomena, which are discussed and
compared with the differential scanning calorimeter (DSC) analysis in this paper. All the phenomena
above show it is feasible to the method for controlling the thermal properties of a material by a proper
design of the dislocation texture.
Micro-Pore Structure and Mechanical Properties of High Temperature Self-Lubricating Biomimetic TiC/FeCrWMoV Cermets
Authors: Wang Yan Jun , Liu Zuo Min
Published: March 2009

A new cermet sinter with sweat-gland micro-pore structure has been developed by powder
metallurgy technology in vacuum. The effects of the pore-forming materials on micro-pore structure
and Y2O3 additions as well mechanical properties of TiC/FeCrWMoV cermets were investigated.
Some typical sweat-gland micro-pores were formed while compound additives TiH2 and CaCO3
adding into the sinter matrix. The porosity of the cermet sinters changes from 20% to 28% with the
compound additives from 6% to 8%, and the micro-pores of sinters exist a regularized and
interpenetrated network structure just like human’s sweat-gland one and obeying to Rayleigh
Distribution. As such the sinters could be easily infiltrated with high-temperature solid lubricant. For
improving the property of the ceramet sinter, the elements Y2O3 of 0.6～0.8% (vol. fraction ) was also
added into the sinter matrix and its effect on the sinter has been also discussed .
Temperature Measurement and Microstructure Control for Rene88DT Superalloy during Laser Rapid Forming
Authors: Tan Hua , Chen Jing , Lin Xin , Zhao Xiao Ming , Huang Wei Dong
Published: March 2009

Laser rapid forming (LRF) is a new manufacturing technology, which has been
developed on the basis of multi-layer laser cladding. In the LRF process, the microstructure has
important effects on the mechanical properties of the partsbut the control of microstructure is a
problem. In this study, the influences of crystallography orientations of substrate and profile of
solid/liquid interface on microstructure were discussed. Further, with the combining of the
columnar to equiaxed transition (CET) model during alloy solidification, the growth law of
microstructure of Rene88DT alloy was established. It has been found that the temperature gradient
was lowest and the solidification velocity was greatest at the solid/liquid interface of the tail of
molten pool, and hence the CET occurs easily at this position. The temperature measurement
system of molten pool was developed by using a two-color infrared thermometer in this study. With
the measurement of temperature gradient of the tail of molten pool by using a two-color infrared
thermometer, the process parameters of laser multi-layer cladding were optimized. Finally,
directional solidification even single crystal was achieved in laser multi-layer cladding.
Effect of Grain Size on Necklace Formation of Magnesium Alloys
Authors: Kaya Ali Arslan , Duygulu Ozgur , Yucel Onuralp , Eliezer Dan
Published: March 2009

In this study, AZ31 in form of sheet, plate and extruded rod and AZ61 wire with different
initial grain sizes were used to investigate the effect of initial grain size on recrystallization behavior
and the formation of fine recrystallized grain (the so-called necklace) structure. Nucleation and
growth of recrystallized grains along grain boundaries has been examined. In order to observe the
effect of initial grain size and deformation on static recrsytallization and necklace formation, the
specimens were annealed at 100-250°C for 10min--2hr. Specimens are also stretched to a total strain
of 10, 20 and 40% at 300°C at an initial cross head speed of 1x10-3 s-1 for dynamic recrystallization
studies. The results suggest that there exists a grain size limit, below which a necklace structure is not
observed.
Annealing Behavior of the Compressed AZ31 Magnesium Alloy with Different Strain
Authors: Liu Tian Mo , Xiao Pan , Pan Fu Sheng , Liu Qing
Published: March 2009

The cold-compressed AZ31 magnesium alloys with different (2.5%, 5%, 7.5%, 10%,
12.5% and 15%) were annealed at different temperatures (573, 623 and 673K) for different time. With
aid of the optical microscopy, and microhardness tester, the microstructural evolution during
annealing at different temperature of the compressed AZ31 has been investigated. The
microstructural characterized results were further related to the hardness test results and the calculated
activation energy. The results showed that for the compressed AZ31, the recrystallization can occur
on the samples with the strain just above 10% and the deformation twinning plays an important role
on the nucleation and grain growth of the recrystallization. It was found that the twinning boundary
was the location of the recrystallization nuclei and a lot of recrystallized grains with equiaxed shape
were found along the twinning boundaries. The relationships among the nuclei orientations and the
crystallographic orientations on both sides of the twining boundary have been statistically
investigated. The effects of the compressed strain and the annealing temperature on annealing
behavior were also discussed based on the experimental results.
The Fatigue Crack Propagation (FCP) Behavior of the Forged Mg-Zn-Y-Zr Alloy
Authors: Xu Dao Kui , Tang Wei Neng , Liu Lu , Xu Yong Bo , Han En-Hou
Published: March 2009

In this paper, the fatigue crack propagation (FCP) behaviors of the forged Mg-Zn-Y-Zr
alloy with different tempers were investigated. At the stage 1 of the FCP, the K-da/dN curves were
distinguished from each other. However, at the stage 2 of the FCP, the K-da/dN curves were almost
the same. SEM fracture analysis indicated that at the stage 2 of FCP, the fracture characteristics of the
forged and T5 samples were similar, with many deep dimples on the fracture surfaces, whereas the
fracture surfaces of the T4 and T6 samples were covered with lots of lamellar cleavage planes. SEM
observations also indicated that the microstructures were distinguished from each other. For the
forged and T5 samples, many big bulk w-Mg3Y2Zn3 phases distributed in the Mg matrix. However,
for the T4 and T6 samples, due to the solid solution treatment, w-Mg3Y2Zn3 phases were almost
completely decomposed and many coarse rod-like 1 precipitates appeared in the interior of the
grains. These firmly confirmed that the variation of the microstructures had great influence on the
fatigue crack propagation (FCP) characteristics of the Mg-Zn-Y-Zr alloy.
Research and Development of Processing Technologies for Wrought Magnesium Alloys
Authors: Pan Fu Sheng , Yang Ming Bo , Ma Yan Long , Cole Gerald S.
Published: March 2009

This paper reviews the latest research and development status of processing technologies
for wrought magnesium alloys including extrusion, forging, (twin-roll) thin strip casting, rolling,
stamping, and superplastic forming. Existing problems and the development trends of these
processing technologies are analyzed and discussed. Up to the present, the R&D on the processing
technologies of wrought magnesium alloys has made great global progress. Nevertheless there is a
long way to achieve large-scale industrialization and application of wrought magnesium alloys.
Study on Solidification Microstructure of AZ31 Alloy Strips by Vertical Twin Roll Casting
Authors: Wang Jian , Jiang Bin , Ding Pei Dao , Pan Fu Sheng , Dai Yong Gang
Published: March 2009

The strip casting of AZ31 were carried out by a Ø250×150mm of vertical twin roll caster
at different casting speeds (9-15m/min) and in different casting temperatures (630-660°C). The
solidification microstructure of the strips was examined. The experiment results showed that the
crystal grain size of the casting was smaller than that of conventional ingot, and decreases while the
casting speed is raised, or the casting temperature decrease. The casting temperature strongly affected
the dendrite structure that changed into sphere-like when the casting temperature was lower. The
appropriate casting temperature for AZ31 magnesium alloy is 640°C, nearby its liquidus temperature.
Microstructures and Mechanical Properties of AZ31B Extruded Sheets from Different Casting Processing
Authors: Le Qi Chi , Zhang Zi Qiang , Cui Jian Zhong
Published: March 2009

A novel way producing magnesium billets, LFEC (low frequency electromagnetic casting
processing), was developed in Northeastern University in China. The high-quality magnesium billets
with less macrosegregation, refined microstructure, and better surface quality were achieved because
the temperature field and the flow pattern of magnesium DC casting were improved significantly after
applying low frequency electromagnetic field. Extrusion is an important plastic deformation process
for magnesium alloys. In this research, the magnesium billets from LFEC were extruded through a
special designed die into sheets. The results of investigation on AZ31B indicated that the extrusion
velocity has obvious effects on their microstructures and mechanical properties and the sheets from
LFEC had finer microstructure and higher mechanical properties than that from conventional DC
casting.
Effect of Nd and Y Addition on Microstructure and Mechanical Properties of Extruded Mg-Zn-Zr Alloy
Authors: Li Qiang , Wang Qu Dong , Li Da Quan , Ding Wen Jiang
Published: March 2009

The effect of Nd and Y addition on the microstructure and mechanical properties of
as-extruded Mg-Zn-Zr magnesium alloy has been investigated in this study. The Mg-Zn-Zr alloy had
11 μm average grain size due to dynamic recrystallization during hot extrusion; but the average grain
sizes of the Mg-Zn-Nd-Y-Zr alloys were markedly reduced to 4 μm by Nd and Y additions. The
lamellar α-Mg + T phase or α-Mg + W phase eutectics at grain boundaries in as-cast Mg-Zn-Nd-Y-Zr
alloys were broken up and MgZn2 precipitates in the matrix are obtained during hot extrusions. The
mechanical properties of as-extruded Mg-Zn-Zr alloy were improved significantly by Nd and Y
additions, especially the elevated temperature strength, which was above 150 MPa in ultimate tensile
strength at 250 °C. These may be ascribed to the very fine grain size, the dispersed T phase or W phase
and the MgZn2 type Laves phase precipitating during hot extrusion.
Aging Behavior of Mg-9Gd-4Y-0.6Mn Alloy
Authors: Deng Zhen Zhen , Zhang Xin Ming , Deng Yun Lai , Xiao Yang , Guo Tian Cai
Published: March 2009

Microstructures and properties of rolled Mg-9Gd-4Y-0.6Mn（nominal wt%）sheets solution
treated at 793K for 12h, and aged at various combinations of temperatures and time were investigated
by hardness measurement, tensile test and TEM. The evolution of the precipitates and their effect on
the mechanical properties of the pre-, peak-, and over-aged tempers were determined, and the optimal
yield tensile strength (YTS) and ultimate tensile strength (UTS) were 276MPa and 287MPa at room
temperature, respectively. It has been found that the addition of Mn into Mg-Gd-Y system contributes
to block behavior of matrix diffuse and increase potential of heat resistance of the alloy.
Preparation of Amorphous Mg-Ni Alloy by Mechanical Alloying and Investigation on its Hydrogen Storage Properties
Authors: Wang Jing Feng , Liu Xin , Ding Pei Dao , Pan Fu Sheng , Hu Yao Bo
Published: March 2009

Amorphous Mg-Ni alloy was prepared by mechanical alloying (MA). The state of the
amorphous phase was analyzed by X-ray diffraction (XRD). The hydrogen desorption capabilities and
electrochemical properties were tested. The analysis of the relationship among the ball-milling
parameters, microstructures and properties of the alloy showed that the milling velocities have a
critical influence on the formation of Mg-Ni amorphous phase. The higher the milling velocity is, the
less the forming time of the amorphous phase is. And with the increasing of the ball-milling time, the
amount of Mg-Ni amorphous phase increases. Whereas the hydrogen desorption capabilities and
electrochemical properties will decrease if the alloy is ball-milled for a long time after the complete
amorphization occurs. Mg, Ni atom ratio also has some obvious influence on the formation of the
amorphous phase and the properties of the alloy. Increasing the content of Ni appropriately will
improve the efficiency of formation of the amorphous phase, the hydrogen desorption capabilities and
electrochemical properties of the alloy.
Expulsion in Resistance Spot Welding of AZ31B Magnesium Alloy
Authors: Zhang Z.D. , Wang Ya Rong , Li D.Q.
Published: March 2009

Expulsion is undesirable during the resistance spot welding due to the weld quality
decrease. The expulsion happening during the resistance spot welding of AZ31B magnesium alloy
was studied related to the distribution of maximum temperature in the interface due to the existing of
contact resistance, and connected with the increased pressure in the nugget due to melting and
expansion of liquid metal. The influence of welding parameters on expulsion is presented and
discussed in this investigation.
Microstructure and Electrochemical Properties of Mg2Ni Substituted by Al, Ti
Authors: Fu Jie , Chen Yu An
Published: March 2009

Mg2-yAlyNi(y=0,0.2,0.3,0.4) and Mg2-aTiaNi (a=0.1,0.2,0.3,0.4) were successfully
synthesized by two-step process. The phase composition, microstructure and morphology of the
alloys were determined by XRD and SEM. It was found that their main phase was Mg2Ni and another
phase, Mg3AlNi2, was observed when Mg in Mg2Ni was partially substituted by Al. The SEM
observations showed a large amount of white grains were uniformly distributed in the matrix of the
alloys substituted by Al, Ti and the variation of microstructure led to promoted electrochemical
properties.
Microstructure and Mechanical Properties of New Particle-Disperse-Reinforced Mg Composite Mg- 6Al- 3B2O3- 1NaCl- 1CaCl2
Authors: Bu Le Ping , Tanaka Shunsuke , Tsushida Masayuki , Ando Shinji , Tonda Hideki
Published: March 2009

In the present study, the conventional process of Compo-casting was carried and the
microstructural and mechanical propertied were then investigated. The matrix alloy used was Mg-
6Al, and B2O3 was added into Mg-Al alloys was investigated at two levels of 3 and 6wt%. The other
experimental materials were NaCl and CaCl2. The microstructures were of the samples analyzed with
Optical Microscopy, SEM and XRD, and the mechanical properties were determined by
micro-hardness and tensile test. The results showed that the mechanical properties of Mg- 6Al-
3B2O3- 1NaCl- 1CaCl2 increased and the microstructure was satisfactory, for a cast alloy, i.e.the
tensile strength was 175MPa.
Surface Modification of AZ91 Magnesium Alloy
Authors: Luan Ben Li , Gray Joy , Yang Lian Xi , Cheong Woo Jae , Shoesmith David
Published: March 2009

Mg is the lightest structural metal with the highest specific strength. It is therefore
considered as a solution for vehicular mass reduction so as to reduce the fuel consumption and
greenhouse gas emission. Unfortunately, Mg and its alloys are highly susceptible to corrosion,
particularly in salt-spray conditions. This has limited its use in the automotive and aerospace
industries, where exposure to harsh service conditions is unavoidable. To improve its corrosion
resistance it is viable to apply a desirable engineering coating on the Mg surface.This communication
discusses the practical aspects of magnesium surface modification based on our review. A novel
immersion coating process is also discussed along with the corrosion behavior of coated and uncoated
AZ91 magnesium alloy.
Magnesium Films Deposited on Different Substrates via Arc PVD Method
Authors: Oktay Gizem , Duygulu Ozgur , Kaya Ali Arslan
Published: March 2009

A hybrid biomaterial was produced by dressing titanium with magnesium in order to utilize
the most advantageous properties of both materials. Titanium was coated with magnesium via arc
physical vapor deposition (PVD) method, and a third agent between titanium and magnesium, as a
bonding medium was also used. The microstructures and chemical compositions of magnesium
arc-PVD coated Ti-6Al-4V alloy and silicon wafer were investigated. The experimental results
showed that Mg can be deposited onto Ti-6Al-4V alloy and on silicon wafer by using arc-PVD
method.
In Situ Observation of Initial Corrosion of AZ91 Alloy with Residual Stress in Wet-Dry Conditions Using Environmental Scanning Electron Microscope
Authors: Chen Jian , Wang Jian Qiu , Han En-Hou , Ke Wei
Published: March 2009

The corrosion of AZ91 magnesium alloy with residual stress was observed in-situ in an
atmosphere of water vapor with cyclic wet-dry conditions using environmental scanning electron
microscope (ESEM). The results showed that the oxygen concentration on the surface generally
increased with the wetting time. And the average corrosion rate of AZ91 alloy with residual stress
(RS) was much larger than that without RS, indicating RS accelerated corrosion. The corrosion
localized at primary α-Mg area at short wetting time, but with the increase of wetting time spread to
the eutectic α-Mg region. Small-size as-cast defects (<50μm) contributed little to the average
corrosion rate while large-size as-cast defects (>100μm) influenced the distribution of water film and
corrosion on the surface.
Damping Properties of 6063Al/Al2O3 SiO2 Particle Reinforced Composites
Authors: Li Yue Ying , Liu Yong Bing , Cao Zhan Yi
Published: March 2009

The stir-casting method was utilized in this paper to synthesize 6063Al/Al2O3·SiO2
reinforced composites consisting of 6063Al alloy as matrix and Al2O3·SiO2 particles as additive with
content of 5%, 10%, 15%, 20% (volume fraction) respectively. Al2O3·SiO2 particles were obtained
from fly ash particles of Steam Power Plant and were pretreated. The shape of these fly ash particles
was spheroidal and ellipsoidal. The damping behavior of 6063Al/Al2O3·SiO2 particle reinforced
composites was studied by measuring the composite’s internal friction values on a Multifunctional
Damping Measurement Apparatus. Under the condition of this series of experiments,
6063Al/Al2O3·SiO2 particle reinforced composites had a higher internal friction values than that of
6063Al matrix and also showed the dependency of internal friction on Al2O3·SiO2 particles volume
fraction, particles dimension, vibration frequency and temperature. There was an increased trend for
internal friction values with increasing the volume fraction of Al2O3·SiO2 particles and decreasing
particles dimension of Al2O3·SiO2 at the same frequency and the different temperature. It has been
found that in the lower frequency, the higher internal friction value was obtained. The internal friction
of the composites increased with increasing temperature. In the case of lower frequency, two damping
peak were observed. A low-temperature damping peak appeared at a temperature near 245°C which a
high-temperature damping peak appeared near 450°C. Based on the experimental results, the
damping mechanism of 6063Al/Al2O3·SiO2 particle reinforced composites was preliminary
discussed. It may be concluded that the damping mechanisms associated with 6063Al/Al2O3·SiO2
reinforced composites include mainly intrinsic damping, dislocation damping and interface damping.
However, only the interface damping mechanism is dominant at high temperature.
Effects of Temperature on the Weldability of Powder Metal Parts Joined by Diffusion Welding
Authors: Kurt Adem , Uygur Ilyas , Ates Hakan
Published: March 2009

Diffusion welding is an advanced bonding process in which similar or dissimilar materials
can be bonded in solid state. In this study, aluminium composite (5% and 15% WC) powders were
compacted at 450 MPa pressure and sintered at 550 oC for 45 minutes in argon atmosphere.and joined
each other by diffusion bonding. The bonding temperatures (585 oC, 600 oC, 615 oC) and dwell time
(185 min) were chosen for the welding process at constant 20 MPa. It has been observed that these
variations on the welding parameter strongly affected the microstructure and the weldability of the
materials.
Numerical Modeling of Low Frequency Electromagnetic Casting of 7XXX Aluminum Alloys
Authors: Zhang Hai Tao , Nagaum Hiromi , Zuo Yu Bo , Cui Jian Zhong
Published: March 2009

Low frequency electromagnetic casting is a new developed technology that appears in the
recent years. In this paper, a comprehensive mathematical model has been developed to describe the
interaction of the multiple physics fields during LFEC (low frequency electromagnetic casting)
process. The model is based on a combination of the commercial finite element package ANSYS and
the commercial finite volume package FLUENT, with the former for calculation of the
electromagnetic field and the latter for calculation of the magnetic driven fluid flow, heat transfer and
solidification. Moreover, the model has been verified against the temperature measurements obtained
from one 7XXX aluminum alloy billet of 200mm in diameter, during the LFEC casting processes,
respectively. There was a good agreement between the calculated results and the measured results.
Further, the effects of electromagnetic frequency on fluid flow, temperature field and solidification
during LFEC process have investigated numerically by using the mathematic model. The choosing
criterion of the electromagnetic frequency during LFEC process has been used in order to obtain the
best structure of the billets by analyzing the effects of fluid flow and temperature field on the
solidification process in the presence of electromagnetic field.
Micromechanism of Plastic Deformation on Elastic Modulus
Authors: Xing Zhong Wen , Bao Jun , Li Xue Chun , Yang Yu Ying
Published: March 2009

The key to enhance the precision of sheet metal stamping parts is accurate prediction and
control of the springback. And one of the dominant factors of springback is the elastic modulus. The
change of elastic modulus with plastic deformation was experimentally studied for the annealed LY12
and the annealed LF21 aluminum alloy respectively, and the changing role of elastic modulus with
plastic deformation was obtained. By inverse pole figure from the X-ray diffraction analysis, the
effects of the material original textures and their changing with plastic deformation on the elastic
modulus were studied. And by positron annihilation lifetime spectrum , the influence of lattice
distortion caused by crystal defect during plastic deformation on the elastic modulus was investigated.
The micromechanism of the elastic modulus changing with plastic deformation for aluminum alloy is
revealed, which lays a foundation for improving the stamping parts’ precision.
3-D Coupled Fluid-Thermal Finite Element Analysis of 3C-Style Nozzle’s Fluid Field of Al Roll-Casting
Authors: Zhou Ying , Huang Ming Hui , Mao Da Heng , Liang Tao
Published: March 2009

Three-dimensional FEM simulations of fluid-thermal analysis of the fluid fields including
the front-box and the 3C-style nozzle of aluminum roll-casting was performed by using FLOTRAN
module of ANSYS. The advanced result analysis based on post-processing of ANSYS was conducted
by MATLAB. According to the allowable inhomogeneity and its application of velocity and
temperature at outlet, the most possible broken regions of aluminum sheets at outlet could be
predicted in the case of speed increasing of the drawing-sheet and thickness reducing of the
aluminium sheet during roll casting.
Microstructure and Grain Refining Performance of a Rapidly Solidified Al-5Ti-1B Master Alloy
Authors: Han Yan Feng , Shu Da , Jin Lan , Wang Jun , Sun Bao De
Published: March 2009

A rapidly solidified Al-5Ti-1B master alloy prepared by the in-rotating-liquid spinning
process has been investigated. It has been found that the in-rotating-liquid spinning process is a
potential rapid solidification method to realize the continuous production of the master alloy wire on a
large scale. The microstructure of the Al-5Ti-1B was evidently improved after being rapidly
solidified. The agglomeration of the TiB2 particle was significantly decreased. Consequently, the
grain size of the purity aluminium refined by the rapidly solidified Al-5Ti-1B was reduced by 15%
compared with that refined by the master alloy prepared under normal conditions.
Growth Rate of Small Fatigue Cracks of Cast Magnesium Alloy at Different Conditions
Authors: Wang Xi Shu , Fan Jing Hong
Published: March 2009

Some differences between the growth behaviors of small fatigue crack of cast AM50
magnesium alloy at different elevated temperature and at open and closed states were investigated
based on in-situ observations with scanning electron microscope (SEM). These results indicate that
the growth rates of small fatigue cracks depend on not only the stress levels but also the elevated
temperature and crack states. The fatigue crack growth rates were estimated based on novel and
conventional methods.
Morphological Changes and Plume Deflection Effect during Pulsed Laser Ablation Deposition of Al
Authors: Perrone A. , Cultrera L. , Duhalde S.
Published: March 2009

The morphological changes and corresponding plume deflection effect during long laser
(XeCl excimer laser, λ=308 nm, τ=30 ns) irradiation of Al target have been investigated,and results
showed that, a the number of laser pulses per site increases, the target morphology changes and
produces a visible deviation of the plasma plume up to 5º. Scanning electron spectroscopy analys of
the target surface related the plume deflection angle to the target morphology and the number of laser
pulses per site. Typically well-defined columnar structures oriented along the laser beam direction
were observed on the target surface. The plume created during the laser ablation was clearly visible to
the naked eye and was recorded by a digital camera. Detailed studies were also performed on the
ablation rate at different laser fluences (4.6 J/cm2-12.5 J/cm2). The morphologies and the thickness of
the Al thin films deposited on Si substrates during the present laser ablation experiments were also
studied. Finally, the scenario explaining the formation of columnar structure on target surface
responsible for the plume deflection effect will be discussed.
Microtexture Development and Flow Stress Saturation during Triaxial Forging of an Al-3Mg-Sc(Zr) Alloy
Authors: Ringeval S. , Piot David , Driver Julian H.
Published: March 2009

An Al-3%Mg-0.25%Sc-0.12%Zr alloy was deformed by triaxial forging at 20-400°C up to
strains of about 3. A study of its textural evolution reveals the tendency towards three symmetrical
variants of a <110><1 10 ><001> component. This experimental observation is supported by a 3D
spatially resolved crystal plasticity analysis. Samples strained at room temperature undergo grain
fragmentation in the form of fine substructures and relatively weak textures. Conversely, at 300°C
and above, more homogeneous intergranular deformation and rotations give rise to stronger textures.
This eventually encourages grain coalescence and thus the development of interpenetrating
“orientation chains”, creating a new type of microstructure. The influence of this texture development
on the specific work hardening behaviour is discussed.
A Cyclic Stress-Strain Constitutive Model for Polycrystalline Magnesium Alloy and its Application
Authors: Zeng Xiang Guo , Wang Qing Yuan , Fan Jing Hong , Gao Zhan Hua , Peng Xiang He
Published: March 2009

The stress-strain behavior of cast magnesium alloy (AM60) was investigated by
strain-controlled cyclic testing carried out on MTS. In order to describe the cyclic stress and strain
properties of AM60 by means of the energy storing characteristics of microstructure during
irreversible deformation, a plastic constitutive model with no yielding surface was developed for
single crystal by adopting a spring-dashpot mechanical system. Plastic dashpots reflecting the
material transient response were introduced to describe the plasticity of slip systems. By utilizing the
KBW self-consistent theory, a polycrystalline plastic constitutive model for Magnesium alloy was
formed. The numerical analysis in the corresponding algorithm is greatly simplified as no process of
searching for the activation of the slip systems and slip directions is required. The cyclic stress-strain
behavior, based on this model, is discussed. The simulation results show good agreement with the
experimental data for AM60.
Atomic Bonding and Properties of Al-Li Alloy in Earlier Ageing Stage
Authors: Gao Ying Jun , Mo Qi Feng , Wang Yu Ling , Zhang Iina , Huang Chuang Gao
Published: March 2009

The atomic bonding of the segregated cell of Al-Li alloy in earlier ageing condition was
calculated according to the empirical electron theory (EET) in solid. The results showed that the
strongest covalent bond was the Al-Al bond in the segregated cell without vacancy, while the
strongest covalent bond was the Al-Li bond in the cell containing vacancy. Since the difference of
electronagativity between the Al and Li atoms was obvious, it was inclined to form the Al-Li
segregated cell of short range order structure in the condition of vacancy joining. The short range
order structure with vacancy was probably the embryo or precursor structure of the metastable phase
' δ (Al3Li). As the ' δ (Al3Li) was coherence with matrix, the bond net strength was enhanced by the
precipitation of ' δ (Al3Li) and hence the alloy was strengthened.
Influence of Ageing Treatment on Microstructure and Properties of 7150 Alloy
Authors: Fan Xi Gang , Jiang Da Ming , Meng Qing Chang , Xian Heng Ze , Li Nian Kui
Published: March 2009

The microstructure after different ageing treatments and its relation to the mechanical
properties and corrosion behavior of 7150 alloy have been investigated. The microstructures were
studied by optical microscopy (OM) and transmission electron microscopy (TEM). It was shown that
suitable heat treatments led to a combination of high strength and corrosion resistance of the alloy.
The yield strength of the alloy is 580MPa in peak aged state, which can be achieved by one step (120
°C/28h) or two step ageing (120°C/6h + 155°C/12h) tempers. The dominant matrix precipitates of the
alloy for one step ageing temper are GP zones and η' phase. The alloy after ageing at 120°C for 28h is
not susceptible to exfoliation corrosion. On the contrary, the alloy after two step ageing (120°C/6h +
155°C/12h) showed worse exfoliation corrosion resistance. The alloy exhibits high strength and good
resistance to the exfoliation corrosion after the ageing treatment of 120°C/6h + 165°C/12h. The
dominant precipitates within the grains are η' phase and η phase. The η phase at the grain boundaries
plays an important role on the corrosion behaviors. The susceptibility of corrosion is associated with
the potential difference between grain and grain boundary, and the characterization of grain boundary
precipitates.
Prediction of Hardness of Aluminum Alloy 7055 by Quench Factor Analysis
Authors: Liu Sheng Dan , Zhang Xin Ming , Huang Z.B. , You J.H.
Published: March 2009

The Vickers hardness time-temperature-properties (TTP) curve of aluminum alloy 7055
was evaluated by interrupted quench technique. The critical temperature range of TTP curve was
determined from 210 °C to 420 °C with the nose temperature of 355 °C. The hardness decreased
rapidly with isothermal duration in the critical temperature range. The hardness of aluminum alloy
7055 was predicted by quench factor analysis using the TTP curve and cooling curves. The predicted
hardness agreed reasonably well with the measured results. The influence of time step and summation
temperature range on the predicted results was studied. The cooling rate through the critical
temperature range had dominant influence on the final hardness of the alloy.