Site preference of ternary alloying elements in Ni3Al:: A first-principles study

First-principles supercell calculations were performed to predict the site preference of Pt, Hf, Cr and Ir in L1(2) Ni3Al. Our calculations showed that, at T = 0 K Pt always prefers Ni sites, while Cr and Hf always prefer Al sites in Ni3Al. The site preference of Ir was found to be strongly composition-dependent: Ir prefers Ni sites in Al-rich and Al sites in Ni-rich Ni3Al, and shows no site preference in stoichiometric Ni3Al. The effects of temperature on site preference of ternary alloying elements were further studied using a statistical-mechanical Wagner-Schottky model in combination with our first-principles calculated point defect formation enthalpies. Our Calculations showed that the site preference of Ir is also strongly affected by temperature. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.