Manufacturing Strategies to Mitigate Deformation Twinning in Magnesium

Abstract

Magnesium (Mg) alloys exhibit poor room temperature ductility, which prohibits forming operations in cost-effective industrial settings and the use of these alloys in critical safety components. Profuse twinning in Mg alloys is widely associated with high strain path anisotropy and low material ductility. Twinning typically propagates across the grains through the autocatalysis phenomena in typical texture conditions. Twin–twin and twin–slip interactions often lead to high strain incompatibilities and eventually failure. One way to avoid such premature failure is to prevent the early nucleation of twins. This research tests a hypothesis that a strong yet ductile phase surrounding each individual grain in traditional polycrystals could inhibit twin accommodation effects and thus twin nucleation and autocatalysis mechanisms at grain boundaries. As a proof-of-concept for testing this hypothesis, sharply textured magnesium sheets plated with different materials were subjected to four-point bending to assess the potential of a surface/grain boundary barrier in limiting twinning extent. The results showed that Mg AZ31 alloy plated with zinc alleviated twin nucleation while improving the strength of the alloy.