Threshold displacement energy in Ni, Al and B2 NiAl

Abstract

For simulation of radiation effects and defects in the Ni-Al system, a new many body potential was developed by joining the equilibrium part of the Mishin's EAM potential with the universal function of Ziegler, Biersack and Littmark at a suitable interatomic spacing and the corresponding pairwise energy from the DFT calculations. To assess the qualities of this potential, we performed molecular dynamics simulations to calculate the threshold displacement energy of pure metals Ni, Al and their NiAl B2 phase superalloy at ambient temperature. It was found that the threshold energy of displacement of nickel in nickel is higher than that in the B2 long-range ordered alloy NiAl in contrast to aluminium, which has lower threshold energy than B2 NiAl. The threshold displacement energy ranges between 14±2 eV and 189±2 eV depending on the crystallographic direction. The lowest threshold energy of two fcc metals (14±2 eV for Al and 28±2 eV for Ni) was found in the direction <101>, these values correspond to the mean value in the easiest directions of atomic displacements and they are in good agreement with many reports from the literature.