Anisotropic Toughness and Crack Growth on Cubic SiC

Molecular dynamics calculation is executed applying the Stillinger-Weber atomic interaction to explore the anisotropic properties of cubic SiC.A solid 3C-SiC with predefined edge crack is subjected to uniaxial tensile load along its crystallographic axis. Three major directions (100), (110) and (111) are studied in this work.The crack propagation path is noticeably different in three directions which in return bring variation in critical energy absorption rate.In (100) plane toughness is 70% higher than in (111) plane.The reason behind this variation is the crack propagation path through the atomic system. In (100) direction, Crack starts growing at 7% strain when the stress is 21.9 GPa.The crack face atoms rather than bonds which hinder the growth and require more energy to break.The sole criterion for growth is bond breaking which drive the crack to branch out and propagate through (110) crystallographic plane. At the point of bifurcation, the solid absorb some energy which increase the fracture toughness.However, in other two planes, (111) and (110), crack sees no obstacle and bonds are parallel to the loading direction.They require lower critical energy release rate for crack growth.So, the crack evolve through the straight path and contain lower toughness.