Molecular dynamics simulations of the melting curves and nucleation of nickel under pressure

WJ Zhang and ZL Liu and YF Peng, PHYSICA B-CONDENSED MATTER, 449, 144-149 (2014).

DOI: 10.1016/j.physb.2014.05.025

Three embedded atom method potentials have been applied to investigate the melting properties of nickel under compression. In these three potentials, Mendelev's potential can reproduce a satisfying melting curve, which accords well with the experiments and first-principles calculations. Thus, we recommend that the Mendelev's potential should be a reliable potential for simulating melting properties of nickel. Using Mendelev's potential, we calculated the melting of Ni with two approaches, i.e., hysteresis approach and two-phase method. Both approaches produce results in very close proximity, with the disagreement less than 4.35% at the applied pressures. Fitting the well- known Simon equation to our melting data yields the melting curves for Ni: 1651(1 + P/35.172)(0.607) (hysteresis approach) and 1725(1 + P/39.812)(0.617) (two-phase approach). Based on the hysteresis method, we investigated in detail the melting nucleation of nickel at high pressure. and found that with pressure increasing, the critical nucleus size r* increases fast first and then decreases, and again rises. When taking account of the Gibbs free energy barrier Delta G*, if found that the Delta G* increase monotonically with pressure up to 300 GPa, and can be described as a third-order polynomial relation. (C) 2014 Elsevier B.V. All rights reserved.

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