Search

Abstract: Microstructure and mechanical properties of Mg–0.6Si–xZn alloys (x =0–1.6wt%) were investigated to reveal the modification effect of Zn on the morphology of eutectic Mg2Si. It was found 0.5–1.3wt% Zn effectively modified the morphology of eutectic Mg2Si from laminated structure to fine fiber, and in turn improved significantly the mechanical properties of Mg–Si alloy. Further increase in Zn content changed Mg2Si from fine fiber to Chinese script shape. It was suggested that the Zn content should not exceed 1.5wt% in Mg–Si–Zn alloy in order to get good mechanical properties. [Copyright &y& Elsevier]

Abstract: Microstructure, biocorrosion behavior and cytotoxicity of an as-extruded Mg–11.3Gd–2.5Zn–0.7Zr (wt%) alloy were studied, in order to develop new biodegradable magnesium alloy. The microstructure of the as-extruded alloy mainly consists of the refinement grains, a lamellar X phase with the 14H-type long period stacking ordered (LPSO) structure in grain boundaries and the 14H-type LPSO structure within initial grains and refinement grains, and a small amount of β phase. The as-extruded alloy has high strength at room temperature. The corrosion rate in Hanks'' solution is only 0.17mm/year and the corrosion mode of the alloy is uniform corrosion, which is much better than that of as-extruded Mg–10.2Gd–3.3Y–0.6Zr (wt%) alloy. Moreover, the cell toxicity grade of the Mg–11.3Gd–2.5Zn–0.7Zr alloy is Grade 1, indicating only slightly having cytotoxicity. The desired results indicate the Mg–Gd–Zn–Zr alloy with LPSO structure will become one of novel promising high-strength biodegradable magnesium alloys. [Copyright &y& Elsevier]

Abstract: As a candidate material for high temperature applications, the Mg–10Gd–2.0Y–0.46Zr alloy may undergo the alternate loading during the service lifetime. Under the total strain-controlled triangular waveform loading, the strength and the evolution of microstructures for the alloy at 573K have been explored. The results show that the alloy presents cyclic softening characteristics at diverse total strain amplitudes. The grain boundary sliding has been detected near the cracks on the surface of the specimen, suggesting that the grain boundary sliding plays an important role in coordination deformation at 573K. Microcracks initiate mostly either at grain boundaries for lower strain amplitudes or at persistent slip bands for higher strain amplitudes, and then propagate along grain boundaries. Due to twinning shear and the dislocations slip, the precipitates in the deformation twins disintegrate to form a small equilibrium phase. The dislocation cells, small angle grain boundaries, as well as dynamic recrystallization are observed in the precipitation-free zone. [Copyright &y& Elsevier]

Abstract: Mn and Zn were selected to develop a Mg–Zn–Mn magnesium alloy for biomedical application due to the good biocompatibility of Zn and Mn elements. Microstructure, mechanical properties, corrosion properties and biocompatibility of the Mg–Zn–Mn alloys have been investigated by use of optical microscope, scanning electron microscope, tensile testing, and blood hemolysis and cell toxicity. Microstructure observation has shown that the addition of Zn and the extrusion significantly refined the grain size of both the as-cast and the extruded magnesium alloys, which mainly contributes to the high tensile strength and good elongation. Polarization test has shown Zn could accelerate the formation of a passivation film, which provides good protection to the magnesium alloy against simulate body fluid. Cell culture and hemolysis tests have shown that the magnesium alloy did not have cell toxicity, showing good cytocompatibility, but the alloy caused hemolysis to blood system. It was suggested that surface modification have to be adopted to improve the blood compatibility of the magnesium alloy for the application in blood environment. [Copyright &y& Elsevier]