Grain character influences on corrosion of ECAPed pure magnesium

This study seeks to clarify the influence of grain character on the corrosion rate of Mg. There is a special need to understand the largely unknown corrosion-grain size relationship for Mg, which nominally displays poor corrosion resistance, since any efforts to reduce or control the rate of Mg corrosion are of large technological significance. In this work, the microstructure is modified by equal channel angular pressing (ECAP) with up to eight passes, to achieve a range of refined microstructures ranging in grain size from a few hundred micrometres to a few micrometres. Results reveal a significant variation in corrosion rate with the number of ECAP passes, and hence grain size, which is of key significance. The results are discussed in terms of grain size, misorientation, along with resultant surface state produced and electrochemical/polarisation signatures collected.