Plasticity of the C15-CaAl2 Laves Phase at Room Temperature

The room temperature plasticity of the cubic C15 CaAl2 Laves phase was investigated using nanomechanical testing and electron microscopy. The correlation between slip traces in the vicinity of nanoindents and crystallographic orientation data allowed us to gain statistical data on the activated slip and crack planes for 10 different crystallographic orientations. Slip on {1 1 1} and {1 1 2} planes was found to be most favourable for all orientations, whereas cracks predominantly occurred on {1 1 2} planes. A constant hardness of 4.9 ± 0.7 GPa and an indentation modulus of 85.5 ± 4.0 GPa for all investigated orientations for a constant strain rate and a strain rate sensitivity of 0.028 ± 0.019 were measured. Micropillar compression tests and transmission electron microscopy confirmed slip on {1 1 1} and {1 1 2} planes with a Burgers vector of <11¯0 > type. This allowed to determine the critical resolved shear stresses as 0.99 ± 0.03 GPa for {1 1 1}<11¯0 > and 0.97 ± 0.07 GPa for {1 1 2}<11¯0 > slip.