Role of bimodal-grained structure with random texture on mechanical and corrosion properties of a Mg-Zn-Nd alloy

Abstract

Fine grained ZN20 alloy was obtained by combining equal-channel angular pressing (ECAP) with extrusion. Microstructural observation showed an obvious grain refinement with an average grain size of 10 µm after ECAP. The original bimodal-grained structure composed of coarse grains with strong basal texture and fine grains with random texture was substituted by a new kind of bimodal-grained structure with finer grains and more random texture after 4 passes ECAP at 300 °C. The combination of grain refinement and texture weakening caused the ductility can be increased by 40% compared with the as-extruded alloy. Immersion test in simulated intestinal fluid revealed an improvement of corrosion resistance after ECAP. Grain refinement can stable the corrosion product layer and basal texture is more beneficial for the corrosion resistance than the non-basal texture.

Keywords

• Magnesium
• ECAP
• Bimodal-grained structure
• Corrosion resistance
• Mechanical property