Amorphization and dislocation evolution mechanisms of single crystalline 6H-SiC

The amorphization and dislocation evolution mechanisms of a single crystal 6H-SiC were systematically investigated by using nano-indentation, high-resolution transmitted electron microscope (HRTEM), molecular dynamics (MD) simulations and the generalized stacking fault (GSF) energy surface analysis. Two major plastic deformation mechanisms of 6H-SiC under nano-indentation were revealed by HRTEM, i.e., (1) an amorphization region near the residual indentation mark, and (2) dislocations below the amorphization region in both the basal and prismatic planes. MD results showed that the amorphization process corresponds to the first pop-in event of the indentation load-displacement curve, while the dislocation nucleation and propagation are related to the consequent pop-in events. The amorphization is confirmed to achieve via an initial transformation from wurtzite structure to an intermediate structure, and then a further amorphization process. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.