Effects of extrusion ratio on microstructure, mechanical and corrosion properties of biodegradable Mg–Nd–Zn–Zr alloy

Abstract

The Mg–3·08Nd–0·27Zn–0·46Zr (wt-%) alloy was hot extruded with different extrusion ratios to refine microstructure and to optimise mechanical properties and corrosion resistance as a biodegradable magnesium alloy. The microstructure was observed by optical microscopy, the mechanical properties were tested at room temperature and the corrosion resistance was evaluated in Hanks’ solution. The results show that the microstructure becomes more and more homogeneous with increasing the extrusion ratio. The mechanical properties of the as extruded alloy are much better than those of the as cast one. Higher strength is obtained with the extrusion ratio of 18, and better elongation is obtained with the extrusion ratio of 25. Corrosion results show that corrosion resistance of the as extruded alloy immersed in Hanks’ solution is better than that of the as cast one, and higher extrusion ratio results in better corrosion resistance. Both the as cast and the as extruded alloys exhibit uniform corrosion, which was interpreted by cyclic polarisation test.