Mechanical and corrosion properties of Mg-Gd-Zn-Zr-Mn biodegradable alloy by hot extrusion

Abstract

Magnesium (Mg) and its alloys showed great potential in biomedical implant applications. However, poor comprehensive performance of mechanical and corrosion properties blocked their wide applications. Mg-3.0Gd-2.7Zn-0.4Zr-0.1Mn (wt%) magnesium alloy was designed in this study for biodegradable application according to elements selection principles. Semicontinuous casting was applied to achieve as-cast alloy, followed by heat treatment and hot extrusion. Microstructure, tensile properties, fractured characteristics and corrosion resistance were investigated to study the feasibility of the alloys as biodegradable materials. Results indicated that hot extruded alloy exhibited appropriate mechanical and corrosion properties with the yield strength and elongation reached to 315.2 MPa and 21.3%, separately. Its corrosion rate calculated by weight loss and hydrogen evolution, immersed in Hank’s solution at 37 ± 0.2 °C for 240 h, were both less than 0.5 mm/year. α-Mg matrix and particle eutectic compounds β-(MgZn)3Gd were in micron-scale, ranged from 2 μm to 10 μm, and lots of dispersed multi-shape precipitations were in nano size. The excellent mechanical and corrosion properties were due to its special multiscale grain structure, making it appear ductile fracture feature with dimples.