Stress-induced structural phase transition of 3C–SiC with TLK structure in a nano-abrading process

Abstract

TLK (Terrace-Ledge-Kink) structure such as surface steps is often found on the surface of SiC materials. Removal behavior of SiC substrates with TLK structure has not been studied in a fixed abrasive polishing under nano-abrasion conditions. In this paper, the effect of TLK structure on the abrasion temperature, stress, and structural transition of SiC substrates during the nano-abrading process is pursued by molecular dynamics (MD) simulation. The results show that the average stress and temperature decrease with the increase of ledge numbers in the TLK structure. It is found that crystalline-to-amorphous (C–A) phase transition occurs. The high-density amorphorization of SiC is induced by a high shear stress, which transforms to low-density amorphous SiC with the release of shear stress. Furthermore, unlike previous reports, the pressure-induced 6-fold coordinated structure in 3C–SiC in this study, however, does not possess a high-pressured phase transition (HPPT) to rocksalt structure; instead, a disordered structure is found. The ductile domain removal goes through two stages: first through the dislocation nucleation and propagation at the initial abrading stage and is then followed by the plastic flow of the amorphous atoms after sliding over the ledge. The presence of TLK structures benefits the plastic deformation of the SiC substrate.