Molecular dynamics simulation study of deformation mechanisms in 3C–SiC during nanometric cutting at elevated temperatures

Abstract

Molecular dynamics (MD) simulation was employed in this study to elucidate the dislocation/amorphization-based plasticity mechanisms in single crystal 3C–SiC during nanometric cutting on different crystallographic orientations across a range of cutting temperatures, 300K to 3000K, using two sorts of interatomic potentials namely analytical bond order potential (ABOP) and Tersoff potential. Of particular interesting finding while cutting the (110)<001̅> was the formation and subsequent annihilation of stacking fault-couple and Lomer–Cottrell (L–C) lock at high temperatures, i.e. 2000K and 3000K, and generation of the cross-junctions between pairs of counter stacking faults meditated by the gliding of Shockley partials at 3000K. Another point of interest was the directional dependency of the mode of nanoscale plasticity, i.e. while dislocation nucleation and stacking fault formation were observed to be dominant during cutting the (110)<001̅>, low defect activity was witnessed for the (010)<100> and (111)<1̅10> crystal setups. Nonetheless, the initial response of 3C–SiC substrate was found to be solid-state amorphization for all the studied cases. Further analysis through virtual X-ray diffraction (XRD) and radial distribution function (RDF) showed the crystal quality and structural changes of the substrate during nanometric cutting. A key observation was that the von Mises stress to cause yielding was reduced by 49% on the (110) crystal plane at 3000K compared to what it took to cut at 300K. The simulation results were supplemented by additional calculations of mechanical properties, generalized stacking faults energy (GSFE) surfaces and ideal shear stresses for the two main slip systems of 3C–SiC given by the employed interatomic potentials.