Molecular dynamics simulation study of deformation mechanisms in 3C-SiC during nanometric cutting at elevated temperatures
SZ Chavoshi and XC Luo, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 654, 400-417 (2016).
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, 300 K to 3000 K, using two sorts of interatomic potentials namely analytical bond order potential (ABOP) and Tersoff potential. Of particular interesting finding while cutting the (110) <00<(1)over bar>> > was the formation and subsequent annihilation of stacking fault-couple and Lomer-Cottrell (L-C) lock at high temperatures, i.e. 2000 K and 3000 K, and generation of the cross junctions between pairs of counter stacking faults meditated by the gliding of Shockley partials at 3000 K. 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) <00<(1)over bar>>, low defect activity was witnessed for the (010) < 100 > and (111) <<(1)over bar>10 > crystal setups. Nonetheless, the initial response of 3G-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 3000 K compared to what it took to cut at 300 K. 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. (C) 2015 Elsevier B.V. All rights reserved.
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