Atomistic simulation of microtwinning at the crack tip in L12 Ni3Al

The mechanisms of deformation at the crack tip in L1₂ Ni₃Al have been studied by molecular dynamics simulations. The stress-induced microtwinning is found to occur at the crack tip when a sufficiently high stress concentration exists. The formation mechanism of the microtwinning is discussed. It is found to be achieved by the emission of Shockley partial dislocations from the crack tip and then slip of the Shockley partial dislocations on adjacent {111} planes. Furthermore, the mechanism of the microtwinning is also discussed from the standpoint of stress.