Influence of secondary phases and their redistribution by deformation on corrosion behaviour of magnesium alloys – A short review

Abstract

Conventional deformation processes such as rolling, extrusion and forging or novel severe plastic deformation techniques significantly alter the microstructure, mechanical properties and corrosion behaviour of magnesium (Mg) alloys. Principally, thermomechanical processes applied to Mg give rise to significant alterations in properties such as dislocation density, twinning, residual stresses, texture, grain size and redistribution of secondary phases. Among them, the redistribution of secondary phases can be regarded as one of the most important factors affecting corrosion resistance due to the relatively reactive nature of Mg and its high tendency to form micro-galvanic couplings with secondary phases. Understanding the elaborate relationship of the varying secondary phase distribution before and after deformation processes on the microstructure and corrosion properties is crucial to optimise the performance of Mg alloys in various applications. Therefore, in this review, the effects of deformation-induced redistribution of secondary phases on the dissolution kinetics, surface morphology and formation of protective oxide layers in Mg alloys were discussed. Furthermore, potential challenges and opportunities for the development of new corrosion-resistant Mg alloys were highlighted.