Atomistic investicagation of crack propagation and parameterization of cohesive traction-separation law in cobalt-titanium alloy.

ABSTRACT: The present study investigates crack propagation of B2 phase Cobalt-Titanium alloy across a range of temperatures (300K, 600K, 900K) under mode-I loading based on constrained three-dimensional atomistic simulations. Stress developments and lattice structure evolution during crack propagation were observed, and a traction-separation law for cohesive zone modeling was developed from these simulations to integrate atomistic insights into macroscopic fracture models. The computations under the mode I condition show that crack growth, even in the nano-scale single-crystal Co-Ti, is in the form of void nucleation, void growth, and coalescence, similar to ductile fracture at the mesoscale. This information can contribute to the understanding and characterizing of Co-Ti’s mechanical response under the mode-I loading conditions and how fracture will propagate on a molecular level. Moreover, the cohesive traction-separation law modeled in this study based on the traction-separation curve can be used in the macro-scale FEM study to simulate arbitrary crack propagation in the bulk material.