Microstructure, Texture Characteristics, Mechanical and Bio-Corrosion Properties of High Strain Rate Rolled Mg–Zn–Sr Alloys

Abstract

Microstructure, texture characteristics, mechanical and bio-corrosion properties of the Mg–5Zn–xSr alloys (x = 0, 0.2, 0.6, 1.0) prepared by high strain rate rolling are carefully studied. A low level of Sr addition enhances dynamic precipitation of nano-scale MgZn2 particles in the as-rolled Mg–5Zn alloy, with 0.6%Sr showing the maximum efficiency. These high-density MgZn2 particles can pin grain boundaries of dynamic recrystallization grains and inhibit their growth. A low level of Sr addition (≤ 0.6%) enhances the (0002) basal texture, but 1.0%Sr is just the reverse. The as-rolled Mg–5Zn–0.6Sr alloy exhibits the best combination of ultimate tensile strength (359 MPa) and elongation to rupture (20%). The high strength can be attributable to a reduced grain size, precipitation and basal texture strengthening. The Mg–5Zn–xSr alloys exhibit excellent bio-corrosion resistance, but a minor Sr addition cannot bring about further bio-corrosion resistance improvement due to the multiple actions of grain size, DRX degree, dynamic precipitates and texture characteristics. The 0.6%Sr addition can greatly improve the strength of the as-rolled alloy at no expense of bio-corrosion resistance.