Deformation mechanisms and defect structures in Heusler intermetallic MnCu$_2$ Al

Intermetallics with crystals derived from body-centered cubic structures are promising materials to enhance the performance and high temperature capability of high-strength alloys both as matrix materials and as strengthening precipitates. Given the ordered nature of these materials, the defect structures that ultimately mediate plasticity can be complex and strongly dependent on processing vis-à-vis the extent of disorder inherited from high temperature phases. Here, we elucidate the elementary characteristics of the defect structures in the Heusler (L2$_1$) intermetallic MnCu$_2$Al as investigated by the orientation-dependent strength and compressive plasticity measured from in situ micro-compression experiments and post-mortem transmission electron microscopy. Our experiments reveal single crystal compressive yield strengths as high as 1.2 GPa and a capacity for stable plastic deformation, accompanied by slip characteristics reminiscent of bcc-derived crystals.