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
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Corrosion
,
Biocompatibility
H.Huang
,
X.Z.Hu
,
Y.Liu
,
M.Bush
,
K.Winchester
,
C.Musca
,
J.Dell
,
L.Faraone
材料科学技术（英文）
An experimental investigation of mechanical properties of thin films using nanoindentation was reported. Silicon nitride thin films with different thicknesses were deposited using plasma enhanced chemical vapor deposition (PECVD) on Si substrate. Nanoindentation was used to measure their elastic modulus and hardness. The results indicated that for a film/substrate bilayer system, the measured mechanical properties are significantly affected by the substrate properties. Empirical formulas were proposed for deconvoluting the film properties from the measured bilayer properties.
关键词:
Mechanical property
,
null
,
null
,
null
Hui Wang Donghui Yang Siyuan He Deping He
材料科学技术（英文）
The open-cell Al foam core sandwiches (AFCSs) were successfully fabricated by using a specially designed Zn-Al-Cu based filler alloy via vibration aided liquid phase bonding method. The effects of the vibration on the bonding seam were investigated and the bonding strength between Al foam core and solid Al alloy face sheet was tested by shearing tests. The results show that vibration can significantly improve the quality of the bonding and the shearing strength of the bonding seam, which implies that this joining method has a good potential in practical applications.
关键词:
Open-cell Al foam core sandwich
,
Liquid phase bonding
,
Vibration
,
Fabrication
,
Mechanical property
Hui Wang Donghui Yang Siyuan He Deping He
材料科学技术（英文）
The open-cell Al foam core sandwiches (AFCSs) were successfully fabricated by using a specially designed Zn-Al-Cu based filler alloy via vibration aided liquid phase bonding method. The effects of the vibration on the bonding seam were investigated and the bonding strength between Al foam core and solid Al alloy face sheet was tested by shearing tests. The results show that vibration can significantly improve the quality of the bonding and the shearing strength of the bonding seam, which implies that this joining method has a good potential in practical applications.
关键词:
Open-cell Al foam core sandwich
,
Liquid phase bonding
,
Vibration
,
Fabrication
,
Mechanical property
Xiaowu HU
,
Fanrong AI
,
Hong YAN
金属学报(英文版)
This paper investigated the influences of pouring temperature and cooling rate on the microstructure development and mechanical properties for casting Al-Si-Cu aluminum alloy. The microstructure of the as-cast samples was characterized by an optical microscope. The results showed that the dendrite arm spacing (DAS, λ) is well refined by pouring at a higher temperature. The λ decreases with increasing pouring temperature due to the multiplication of the nucleation sites in the superheating liquid melt, and the mechanical properties, such as microhardness and ultimate tensile strength increase correspondingly, while the elongation decreases. The relationships between microhardness and λ for the samples cooled in metal mould and sand mould, are given as HV=118.9 - 1.246 λ and HV=115.2 - 1.029 λ, respectively. The effects of the cooling rate controlled by using permanent mould casting and sand mould casing processes (the cooling medium is air and sand, respectively) on the dendrite arm spacing and mechanical properties are similar to the effect of the pouring temperature.
关键词:
Pouring temperature
,
null
,
null
,
null
,
null
Jianbo YU
,
Zhongming REN
金属学报(英文版)
doi:10.1016/S1006-7191(08)60068-X
The effects of electromagnetic vibration on the grain refinement in directional solidification were investigated. It was found that the electromagnetic vibration applied in the melt not only can refine grains remarkably but also can enhance both tensile strength and ductility values of Al-6%Si alloy. SEM graphs show that coarse dendrite structure was broken up into a somewhat globular structure, and the morphology of eutectic silicon was changed from flaky to fibrous under electromagnetic vibration treatment. The refine mechanism under electromagnetic vibration was discussed.
关键词:
Electromagnetic vibration
,
null
,
null
,
null
Wattanachai Prukkanon
,
Satit Chanpum
,
Chaowalit Limmaneevichitr
材料科学技术（英文）
The effect of Sc on precipitation hardening of AlSi6Mg was studied. Zr was previously reported that it increased the effectiveness of Sc in wrought aluminum in many areas so Zr was also used together with Sc in this study. Different levels of Sc and Zr additions were added to AlSi6Mg before casting in the permanent mold. The samples were precipitation hardened at different aging temperatures and for various aging time before testing for tensile strength and hardness. It was found that Sc addition into Al6SiMg can change its response to age hardening. Additions of Sc and Sc with Zr increased both yield strength and hardness for both aging temperatures. In addition, Sc was found to modify eutectic Si to obtain fibrous morphology. This effect of Sc on eutectic silicon modification has never been reported before.
关键词:
Scandium
,
null
,
null
,
null
,
null
,
null
Mingzhen MA
,
Dayong CAI
,
Tianhua WEI
材料科学技术（英文）
Direct reaction synthesis (DRS), based on the principle of self-propagating high-temperature synthesis (SHS), is a new method for preparing particulate metal matrix composites. TiCP/Al-4.5Cu-0.8Mg composites were fabricated by DRS. Particulate composites were fabricated with Ti carbide (TiC) particles, generally less than 1.0µm. The reacted, thermal extruded samples exhibit a homogeneous distribution of fine TiC particles in Al-4.5Cu-0.8Mg matrix. Mechanical property evaluation of the composites has revealed a very high tensile strength relative to the matrix alloy. Fractographic analysis indicates ductile failure.
关键词:
TiCP/Al-4.5Cu-0.8Mg composites
,
null
,
null
,
null
YANG
,
Jianting GUO
,
Jiyang ZHOU
材料科学技术（英文）
A NiAl-based composite with HfB2 dispersed particles has been synthesized by mechanical alloying of Ni, Al, Hf and C powders. The formation mechanism of NiAl-HfC during milling can be attributed to two chemical reactions: Ni+AlNiAl+ΔH; Hf+C→HfC+ΔH, induced by mechanical collision in a certain period of time, which results in an abrupt exothemic reaction. Hot pressing (HP) and hot isostatic pressing (HIP) have been used to make the NiAl-10HfC compacts near fully dense. Compressive testing from room temperature to 1000℃ indicated that the yield stress of NiAl-10HfC composite is 3~4 times higher than that of cast NiAl and correspond to the MA NiAl-10TiB2 composite. In the meantime, yield strength at high temperature is dependent on strain rate, and deformation is controlled by diffusion mechanism.
关键词:
NiAl composite
,
null
,
null
,
null
,
null
Peilin LI
,
Zhongfeng XU
,
Chun YU
,
Hao LU
,
Junshan YAO
,
Guoyu CHEN
金属学报(英文版)
The 2219 aluminum alloy under refilling friction stir welding (RF-FSW) was investigated. The micrographs showed that the bead could be divided into six zones, and the grain size and shape were greatly different in these zones. According to the microstructure analysis, the weld nugget zone and the shoulder stirring zone consisted of equiaxed grains, while the grains in the heat affected zone were seriously coarsened. It was obvious that bending deformation occurred in the thermo-mechanically affected zone. According to the microhardness analysis, the lowest hardness of the weld was at the thermo-mechanically affected zone, and the microhardness increased with the retraction of the stir-pin. The tensile strength and elongation of the bead were 70% and 80% of the base metal, respectively. The tensile strength was slightly different for the stable stage and the retraction stage, while the elongation decreased in the retraction stage. The mechanical properties and microstructure responded to different retraction speed were analyzed, and it showed that the elongation decreased with increasing retraction speed.
关键词:
Aluminium alloy
,
null
,
null
,
null
