Atomistic simulations of Paidar–Pope–Vitek lock formation in Ni3Al

• DOI: 10.1016/j.commatsci.2003.10.003
• Publication Date: 2003-12-12T14:45:28Z
• Authors: A.H.W. Ngan; M. Wen; C.H. Woo
• Keywords: Lock (firearm)

Abstract The thermally activated process of Paidar–Pope–Vitek (PPV) lock formation in the L1 2 intermetallic Ni 3 Al is simulated using the “nudged elastic band” method with an embedded atom potential. It is found that the one-step PPV lock is intrinsically unstable, but it can be stabilized by a large enough Escaig stress. The two-step PPV lock can be formed with a low activation energy when the one-step lock is involved as an intermediate step. In this case, the overall activation energy is about 1 eV, in reasonable agreement with the range of 0.5–0.9 eV expected from experimental observation of the flow stress anomaly in Ni 3 Al. High Escaig stresses are required to stabilize the one-step lock, and the absence of such high stresses in the micro-strain regime is thought to be the underlying reason for the absence of the flow stress anomaly in micro-strain conditions.