A continuous net-like eutectic structure enhances the corrosion resistance of Mg alloys

Abstract

Mg alloys degrade rather rapidly in a physiological environment, although they have good biocompatibility andfavorable mechanical properties. In this study, Ti was introduced into AZ61 alloy fabricated by selective laser melting,aiming to improve the corrosion resistance. Results indicated that Ti promoted the formation of Al-enriched eutectic α phaseand reduced the formation of β-Mg17Al12 phase. With Ti content reaching to 0.5 wt.%, the Al-enriched eutectic α phaseconstructed a continuous net-like structure along the grain boundaries, which could act as a barrier to prevent the Mg matrixfrom corrosion progression. On the other hand, the Al-enriched eutectic α phase was less cathodic than β-Mg17Al12 phase inAZ61, thus alleviating the corrosion progress due to the decreased potential difference. As a consequence, the degradationrate dramatically decreased from 0.74 to 0.24 mg·cm-2·d-1. Meanwhile, the compressive strength and microhardness wereincreased by 59.4% and 15.6%, respectively. Moreover, the Ti-contained AZ61 alloy exhibited improved cytocompatibility.It was suggested that Ti-contained AZ61 alloy was a promising material for bone implants application.