Lattice instability in bgr;hyphen;SiC and simulation of brittle fracture

摘要

Brittle fracture of bgr;hyphen;SiC (polytype 3C) under hydrostatic tension has been modeled by molecular dynamics simulation using an interatomic potential function that treats the solid as fully covalent. The critical stress at which the lattice becomes structurally unstable is shown to agree quantitatively with that predicted by stability analysis based on elastic stiffness coefficients. The instability mode is the spinodal (vanishing of bulk modulus), and decohesion occurs as spontaneous nucleation of cracking on lcub;111rcub; shuffle planes. Atomic relaxation on the newly generated cracked surfaces appears to take place immediately following crack opening.