Crack front propagation by kink formation

The fracture of a three-dimensional brittle solid generates two-dimensional surfaces, which are formed behind a one-dimensional crack front. For quasi-static cracks on a (111) cleavage plane in silicon front propagation by kink-pair formation was proposed and proven by a reaction pathway analysis with Stillinger-Weber potentials. Here, we demonstrate that the kink-pair mechanism is much more general: we also observe it in molecular- dynamics simulations of a complex metallic alloy, the C15 NbCr 2 Friauf-Laves phase, where we applied carefully selected embedded-atom-method potentials. The numerical experiments highlight that kink formation is essential for crack propagation in any brittle material.