Microstructure and Corrosion Behavior of Extruded Mg-Sn-Y Alloys

Abstract

Magnesium and its alloys, with their unique properties such as high strength/density ratio, good castability, and machinability, have found several applications in the aerospace and automotive industries. One of the reasons that restrict their widespread applicability is their poor corrosion resistance since Mg is readily oxidized in the presence of oxygen and humidity. The oxide layer is pseudo-passive and non-protective. The present effort tried to improve the passivity of this layer with the addition of alloying elements such as Tin (Sn) and Yttrium (Y) to create phases that interact differently with the oxidizing environment, thereby improving the corrosion resistance. In this work, the corrosion behavior of pure magnesium and Mg-5Sn-xY (x = 0.5, 1, 2 wt.%) were evaluated using immersion and potentiodynamic polarization tests. XRD, SEM-EDS, and EBSD have investigated the microstructure and elemental composition of the alloys. The present study is focused on elucidating the microstructure-corrosion relationship in Mg-Sn-Y alloys.