Waled Elthalabawy Tahir Khan
材料科学技术（英文）
The excellent corrosion resistance, formability and strength make stainless steels versatile for diverse applications. However, its high specific strength and good crashworthiness make it suitable for transportation and aerospace industry. On the other hand, the need to reduce the weight of vehicle and aerospace components has created renewed interest in the use of magnesium alloys. Due to their differences in physical and metallurgical
properties, bonding of the 316L steel and AZ31 magnesium alloy using conventional fusion welding methods encountered many limitations. Therefore, the use of liquid phase forming interlayers is required to overcome the differences in their properties, eliminates the need for a high bonding pressure to achieve intimate contact between the bonded surfaces. Both Cu and Ni interlayers successively formed a eutectic phase with magnesium. The formation of intermetallics and Mg diffusion caused the eutectic phase to isothermally solidify with increasing bonding time. The formation of ternary intermetallic phases (λ1 and B2) impaired the bond shear strength particularly at the end of the isothermal solidification stage where no eutectic phase was observed.
However, the joints showed a higher shear strength value of 57 MPa when bonding with Cu interlayer at 530°C for 30 min compared to 32 MPa when Ni interlayer was used at 510°C for 20 min.
关键词:
Magnesium alloy
,
Stainless steel
,
Eutectic Bonding
,
Microstructure
,
Shear strength
刘志勇
,
许庆彦
,
柳百成
金属学报
针对工程上应用广泛的AZ91D压铸镁合金, 建立了其凝固过程中微观组织演化的数学物理模型. 采用改进的三维微观元胞自动机(CA)模型, 耦合三维溶质场计算,结合压铸镁合金进行了微观组织模拟. 模拟结果再现了在多晶粒同时生长的情况下,初生晶间的溶质扩散、溶质富集直至共晶转变的全部演化过程. 应用此模型模拟了实际AZ91D压铸件不同部位的微观组织, 模拟结果与金相观察结果符合较好.
关键词:
镁合金
,
Solute concentration field
,
Magnesium alloy
,
Die casting
Mengwu WU
,
Shoumei XIONG
金属学报(英文版)
A numerical model based on the cellular automaton method for the three-dimensional simulation of dendritic growth of magnesium alloy was developed. The growth kinetics was calculated from the complete solution of the transport equations. By constructing a three-dimensional anisotropy model with the cubic CA cells, simulation of dendritic growth of magnesium alloy with six-fold symmetry in the basal plane was achieved. The model was applied to simulate the equiaxed dendritic growth and columnar dendritic growth under directional solidification, and its capability was addressed by comparing the simulated results to experimental results and those in the previously published works. Meanwhile, the three-dimensional simulated results were also compared with that of in two dimensions, offering a deep insight into the microstructure formation of magnesium alloy during solidification.
关键词:
Magnesium alloy
,
null
,
null
,
null
Wenhui LIU
,
Yangai LIU
,
Shoumei XIONG
,
Baicheng LIU
,
Y.Matsumoto
,
M.Murakami
材料科学技术（英文）
Casting pressure conditions have great influences on the casting defects, such as gas porosity, shrinkage porosity and gas holes. A Mg cylinder head cover die casting was used to experimentally study the influences of casting pressure, the loading time and the piston position of pressure intensification on the variation of pressure and the quality of casting. The results show that casting pressure, the loading time and the piston position of pressure intensification have great influences on the pressure variations in the mold, the quality and performance of casting. The external quality, the density and the tensile strength of casting were improved with the increase of casting pressure and the piston position of pressure intensification and the decrease of the loading time of pressure intensification.
关键词:
Magnesium alloy
,
null
,
null
,
null
,
null
Ping YANG
材料科学技术（英文）
Channel die compression and initial textures are used to activate different deformation mechanisms in a fine-grained magnesium alloy AZ31. The $\sigma$-$\varepsilon$ curves, microstructures and, particularly, textures are analyzed to reveal different deformation mechanisms and to compare with those of coarse grained samples. Dominant double-prismatic slip, {101ˉ2} twinning and basal slip are detected in three types of samples, respectively, which is similar to those of coarse grained samples. The detrimental effect of shear band formation or {101ˉ1} twinning is limited in fine grained microstructure. In addition to the higher flow stress at low temperature an early decrease in flow stress at higher temperature is also found in fine-grained samples in comparison with their coarse-grained counterparts. This softening is ascribed to the early dynamic recrystallization or grain boundary glide.
关键词:
Magnesium alloy
,
null
,
null
,
null
Canfeng FANG
,
Xingguo ZHANG
,
Hai HAO
,
Shouhua JI
,
Junze JIN
材料科学技术（英文）
The solidification behaviors of AZ61 magnesium alloy under a high magnetic field were studied. The corrosion property of AZ61 alloy was investigated in a solution of 3.5 mol/L NaCl by measuring electrochemical polarization. The results show that the high magnetic field can refine microstructure and benefit aluminum transfer. The crystal of α-Mg is induced to orient with their c-axis parallel to the magnetic field. The corrosion studies indicate that different crystal plane of magnesium has different corrosion property. The passivating films on the a- and b-planes have higher corrosion resistance than that on the c-plane. Aligned structure affects the corrosion property of AZ61 magnesium alloy.
关键词:
Magnesium alloy
,
null
,
null
,
null
Chen Bin
,
Yin Kai-Yang
,
Lu Tian-Feng
,
Sun Bing-Yi
,
Dong Qing
,
Zheng Jing-Xu
,
Lu Chen
,
Li Zhan-Chun
材料科学技术（英文）
doi:10.1016/j.jmst.2016.06.010
AZ91/HA composite was prepared by AZ91 magnesium alloy and porous HA using squeeze casting method. The microstructure and mechanical property of the AZ91/HA composite were studied. The results show that the molten AZ91 alloy completely infiltrated the preform without destroying the porous structure of the HA preform. The compressive strength of AZ91/HA composite increased significantly compared with that of the porous HA. The immersion test indicated that AZ91 alloy shows a lower corrosion resistance and is easier to be corroded in comparison with HA.
关键词:
Biodegradable
,
Magnesium alloy
,
Porous HA
,
Composite
,
Squeeze casting
Wuxiao WANG
,
Bailing JIANG
,
Sen YUAN
,
Wanqi JIE
材料科学技术（英文）
The liquid quenching method was adopted to study the solidification morphology and microstructure of AZ91D Mg alloy in semisolid. The results indicate that cooling rate has important effects upon the solidification structures. Under the cooling rate of liquid quenching, primary α-phase grows first by attaching on the original α grains, or independent nucleation and growth. The high cooling rate makes primary α-phase grow in "rags" or dendrite shape. Eutectic solidification is carried out in terms of both dissociated growth and symbiotic growth. The dissociated growth forms rough and large β-phase at grain boundaries, while symbiotic growth forms eutectic of laminar structure. The small liquid pool inside the original α-phase solidifies basically in the same way as that of intergranular liquid, but owing to less amount of liquid phase, the eutectic solidification is mainly carried out in the dissociated pattern.
关键词:
Magnesium alloy
,
液淬
,
凝固方式
,
凝固组织
Yali GAO
,
Dangsheng XIONG
,
Cunshan WANG
,
Yongzhe CHEN
金属学报(英文版)
doi:10.1016/S1006-7191(08)60085-X
Al-Si alloy coatings were prepared on AZ91HP magnesium alloy by broad-beam laser cladding; the influences of the powers on the microstructure and properties of the coatings were discussed. It was found that the microstructure of the coatings at the powers of 3 and 3.5kW was characterized by Mg2Si dendrites, and needle-like Mg2Al3(hcp) dispersing in the Mg17Al12 matrix, whereas the coating at the power of 2.5 kW was composed of the petal-like Mg2Al3 (fcc) as well as the needle-like Mg2Al3(hcp). The coating at the power of 4 kW appeared as α-Mg solid solution and Mg2Si, Mg17Al12, as well as Mg2Al3 (hcp). The coatings with the powers of 3 and 3.5 kW exhibited higher microhardness and better wear resistance because of more Mg2Si and Mg17Al12. However, the coating at the power of 2.5 kW displayed better corrosion resistance.
关键词:
Magnesium alloy
,
null
,
null
,
null
