Controlling Corrosion Resistance of a Biodegradable Mg–Y–Zn Alloy with LPSO Phases via Multi-pass ECAP Process

Abstract

Mg-RE (rear earth) alloys with long period stacking (LPSO) structures have great potential in biomedical applications. The present work focused on the microstructure and corrosion behaviors of Mg98.5Y1Zn0.5 alloys with 18R LPSO structure after equal channel angular pressing (ECAP). The results showed that the ECAP process changed the grain size and the distribution of LPSO particles thus controlled the total corrosion rates of Mg98.5Y1Zn0.5 alloys. During the ECAP process from 0p to 12p, the grain size reduced from 160–180 μm (as-cast) to 6–8 μm (12p). The LPSO structures became kinked (4p), then started to be broken into smaller pieces (8p), and at last comminuted to fine particles and redistributed uniformly inside the matrix (12p). The improvement in the corrosion resistance for ECAP samples was obtained from 0p to 8p, with the corrosion rate reduced from 3.24 mm/year (0p) to 2.35 mm/year (8p) in simulated body fluid, and the 12p ECAP alloy exhibited the highest corrosion rate of 4.54 mm/year.