Development of an interatomic potential for the Ni-Al system

Abstract

We construct an interatomic potential for the Ni-Al system within the embedded-atom method formalism. The potential is based on previously developed accurate potentials for pure Ni and Al. The cross-interactions are fitted to experimental cohesive energy, lattice parameter and elastic constants of B2-NiAl, as well as to ab initio formation energies of several real or imaginary intermetallic compounds with different crystal structures and chemical compositions. The potential accurately reproduces a variety of physical properties of the NiAl and Ni₃Al phases, and shows reasonable agreement with experimental and ab initio data for phase stability across the Ni-Al phase diagram. Most of the properties reproduced by the new potential were not involved in the fitting process, which demonstrates its excellent transferability. Advantages and certain weaknesses of the new potential in comparison with other existing potentials are discussed in detail. The potential is expected to be especially suitable for simulations of heterophase interfaces and mechanical behavior of Ni-Al alloys.

Keywords:

• atomistic simulations
• interatomic potential
• Ni-Al system
• phase stability
• interfaces
• point defects

Acknowledgements

This work was supported by the National Aeronautics and Space Administration through the Langley Research Center (NRA # NNX08AC07A).

Notes

Note

1. B2-NiAl melts congruently. Experimental data for the melting point of Ni₃Al vary from 1645 to 1668 K 63. There is even a controversy about whether this compound melts congruently or via a γ − γ′ eutectic. We use the lower bound of 1645 K.