Hou Lida
,
Li Zhen
,
Zhao Hong
,
Pan Yu
,
Pavlinich Sergey
,
Liu Xiwei
,
Li Xinlin
,
Zheng Yufeng
,
Li Li
材料科学技术（英文）
doi:10.1016/j.jmst.2016.07.004
The microstructure evolution and mechanical properties of biodegradable Mg-3Sn-1Zn-0.5Mn alloys were investigated by the optical microscopy, X-ray diffractometer and a universal material testing machine. The corrosion and degradation behaviors were studied by potentiodynamic polarization method and immersion test in a simulated body fluid (SBF). It was found that the as-extruded Mg-3Sn-1Zn-0.5Mn alloy has the fine equiaxed grains which underwent complete dynamic recrystallization during the hot extrusion process, with the second phase particles of Mg2Sn precipitated on the grain boundaries and inside the grains. The tensile strength and elongation of as-extruded Mg-3Sn-1Zn-0.5Mn alloys were 244?±?3.7?MPa and 19.3%?±?1.7%, respectively. The potentiodynamic polarization curves in SBF solution indicated the better corrosion resistance of the as-extruded Mg-3Sn-1Zn-0.5Mn alloy in the SBF solution. Immersion test in the SBF solution for 720?h revealed that the corrosion rate of as-extruded Mg-3Sn-1Zn-0.5Mn alloy was nearly 4?±?0.33?mm/year. The hemolysis rate of as-extruded Mg-3Sn-1Zn-0.5Mn alloy was lower than the safe value of 5% according to ISO 10993-4. As-extruded Mg-3Sn-1Zn-0.5Mn alloy showed good biocompatibility after being implanted into the dorsal muscle and the femoral shaft of the rabbit, and no abnormalities were found after short-term implantation. It was revealed that the as-extruded Mg-3Sn-1Zn-0.5Mn alloy is a promising material for biodegradable implants, which possesses an interesting combination of preferred mechanical properties, better corrosion resistance and biocompatibility.
关键词:
Biodegradable magnesium alloy
,
Extrusion
,
Mechanical property
,
Corrosion
,
Biocompatibility
Hongjun HU
,
Dingfei ZHANG
,
Fusheng PAN
,
Mingbo YANG
金属学报(英文版)
doi:10.1016/S1006-7191(08)60109-X
To reduce the surface cracks of extrusion rod for AZ31 magnesium caused by nonhomogeneous metal flow in extrusion process, 3D computer finite element (FE) simulations of extruding a wrought magnesium alloy AZ31 into rods have been performed and the results have been verified in extrusion experiments under identical conditions. The tendency to generate the dead zone is decreased by employing the die angle 60° at the cone-shaped die comparing with the die angle 180°. The surface additional tensile stresses of the rod at the die exit are decreased greatly so that the surface cracks caused are avoided by using the die angle 60°. The extrusion die with die angle 180 °would increase the higher temperature rise and possibility of crac formation on the rod surface that caused by die angle 60° and temperature rise decrease tensile strength of the AZ31 rod. The experimental results show that die angle 180 °could cause continuous cracks on the surface of the extruded rod. The extrusion force required is reduced approximately 15 ton by employing the die angle 60°. Theoretical results obtained by the DeformTM-3D simulation agreed well with the experiments. The obtained results provide the fundamental and also practical guidelines for the design and correction of dies to produce magnesium rod with good surface quality.
关键词:
Extrusion
,
null
,
null
,
null
,
null
Shijian YUAN
材料科学技术（英文）
To reduce defects, such as the shrinkage cavity and the surface cracks caused by non-homogeneous metal flow in extrusion process, an extrusion method was proposed by using a die with the guiding angle. Numerical simulation and experiment were conducted to investigate the metal flow in this extrusion process. It is shown that the stress state at the bottom of the die is changed. The tendency to generate the dead zone is decreased by employing the guiding angle at the die entrance. The shrinkage cavity is reduced because the non-homogeneous metal flow at the final stage of extrusion is improved. The axial stress is decreased greatly so that the surface cracks caused by additional stress are avoided.
关键词:
Guiding angle
,
挤压
,
金属流动
,
缺陷
Wenbin FANG
,
Hongfei SUN
,
Erde WANG
,
Yaohong GENG
材料科学技术（英文）
A new method using lead coated glass fiber to produce continuous wire for battery grid of electric vehicles (EVs) and hybrid electric vehicles (HEVs) was introduced. Under equal flow, both the maximum and minimum theoretical value of gap size were studied and estimation equation was established. The experimental results show that the gap size is a key parameter for the continuous coating extrusion process. Its maximum value (Hmax) is 0.24 mm and the minimum one (Hmin) is 0.12 mm. At a gap size of 0.18 mm, the maximum of metal extrusion per unit of time and optimal coating speed could be obtained.
关键词:
Lead
,
null
,
null
,
null
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null
