Microstructure and mechanical properties of as-cast and extruded biomedical Mg-Zn-Y-Zr-Ca alloy at different temperatures
(1. College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
2. Shanxi Key Laboratory of Advanced Magnesium-based Materials, Taiyuan 030024, China)
2. Shanxi Key Laboratory of Advanced Magnesium-based Materials, Taiyuan 030024, China)
Abstract: A type of biomedical magnesium alloy Mg-3Zn-1Y-0.6Zr-0.5Ca was cast and extruded at three extrusion temperatures of 270, 300 and 330 °C. The microstructure and mechanical properties of the cast and extruded alloys, tailored at different extrusion parameters, were investigated using tensile tests, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, transmission electron microscopy and electron backscattered diffraction. Optimum comprehensive mechanical properties are achieved in the alloy extruded at 270 °C, the ultimate tensile strength and the elongation reach 315 MPa and 26%, respectively, which is deemed to be associated with the grain refinement, weak basal texture and second phases strengthening. After hot extrusion, extensive dynamic recrystallization is found in the Mg-3Zn-1Y-0.6Zr-0.5Ca alloy. Continuous Mg3YZn6 phase bands are gradually broken into discontinuous chain-like or dot-like structures, and the grains distribute more uniformly. The as-extruded Mg-3Zn-1Y-0.6Zr-0.5Ca alloy exhibits a weak texture with (0001) basal planes parallel to the extrusion direction.
Key words: magnesium alloy; quasicrystal; hot extrusion; dynamic recrystallization; mechanical properties