Crack-path bifurcation, arrest, and renucleation in porous 3C-SiC

Abstract

This paper presents the physics of crack-path formation in single-crystalline [Formula: see text]-SiC containing an isolated pore as a combination of three physical processes: bifurcation, arrest, and renucleation. Results show that, depending on the symmetry of the crystal structure, three distinctive crack paths form: (i) crack bifurcates and propagates in the domain without being affected by the pore, (ii) crack bifurcates and interacts strongly with the pore leading to a termination of the propagating crack, and (iii) crack does not bifurcate, retains its propagation path on the symmetry plane, and gets arrested at the pore. The continued growth of the terminated crack requires crack renucleation at the pore edge, and the renucleation event enhances the effective toughness of the domain. The degree of toughness enhancement depends on the pore diameter, the crack length, and the crack–pore distance. While the crystallographic anisotropy forms the basis for bifurcation, the conditions for bifurcation and arrest are governed by the strength of elastic interactions emanating from the crack tip and the pore edge. As such, there exists a critical crack–pore distance of 40 nm below which the crack–porosity interaction is strong enough to enforce the bifurcated crack to divert toward the pore, leading to instant termination of its growth.