A Concise Note on Deformation Twinning and Spall Failure in Magnesium at the Extremes

Abstract

The high yield strength and low density, potential for further improvements in strength and ductility, and potential for use in defense applications of magnesium and its alloys have garnered serious interest in recent years. However, magnesium and its alloys have also shown a relatively low resistance to void-growth mediated spall failure when compared to other materials such as aluminum, copper, and titanium alloys. The lower spall strength indicates a propensity for failure under tension at the extremes. The common processing methods employed to manufacture these metals may introduce potential void nucleation sites at grain boundaries and second phase inclusions, which can make spall failure more likely. The relationship between the matrix strength and potential void nucleation sites remains largely unexplored in magnesium and its alloys. In this work, the literature regarding experimental observation of deformation mechanisms and spall failure processes active in single crystal and polycrystalline (pure and alloyed) magnesium is explored with a particular emphasis on examining deformation twinning and potential void nucleation sites through ex-situ (postmortem) microscopy. This concise note clearly exposes the need for more research to develop a better understanding of the underlying deformation mechanisms and failure processes active in single crystal and polycrystalline (pure and alloyed) Mg at the extremes.