First-principles calculations of Ni-Al-Cr alloys using cluster-plus-glue-atom model

Abstract

The short range order and physical properties of Ni-Al-Cr alloys are studied by using the cluster-plus-glue-atom model. In the formula [Al-Ni₁₂]Al_<i>x</i>Cr_3–<i>x</i>, <i>x</i> = 0, 0.5, 1.0, 1.5, 2.0, 2.5, Al atom is selected as the center of cluster, then twelve Ni atoms which are arranged at the nearest neighboring sites constructe a cluster, and Al atoms and Cr atoms which are located at second neighboring sites are glue atoms. The results of formation energy show that the configurations of cluster-plus-glue-atoms model are more stable than the other configurations with all compositions. The results of difference charge density show that the charge density transfer of Ni-Al-Cr system is mainly accumulated between Ni and Al atoms or between Ni and Cr atoms. It means that Ni-Al and Ni-Cr are more easily bonded than Ni-Ni and Al-Cr. The electronic band structures indicate that Ni-Al-Cr alloy has conductor properties. The hybrid effects between Ni-3d and Al-3p or Ni-3d and Cr-3d are obvious, which verifies that there are strong interactions between Ni and Al atoms or between Ni and Cr atoms.