Plastic deformation of single crystalline C14 Mg2Ca Laves phase at room temperature

Abstract

Intermetallic phases, such as Mg2Ca, have been shown to significantly improve the creep strength of magnesium alloys. However, the relevant deformation mechanisms of the intermetallics for further alloy development are largely unknown as the application temperature of the intermetallic-metallic composites lies in their brittle low temperature regime. In this study, we investigated the deformation mechanisms of the hexagonal Mg2Ca Laves phase at the same size scale (μm) as in intermetallic-metallic alloys and at room temperature using nanomechanical test methods. We identified active slip planes by a statistical evaluation of slip traces formed around nanoindentations and measured the corresponding critical resolved shear stresses for each slip system by compression of single crystalline micropillars in selected orientations. Deformation occurs on basal, 1st and 2nd order pyramidal as well as 1st and 2nd order prismatic planes and the critical stresses are of the order of 0.44 GPa–0.59 GPa with the lowest value obtained on the 1st order prismatic planes. Finally, we discuss the possible slip systems on a theoretical basis in terms of their local atomic structure.