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

• Published in: Acta materialia Vol. 54; no. 4; pp. 1147 - 1154
• Main Authors: JIANG, C, SORDELET, D. J, GLEESON, B
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Science 01-02-2006
• Subjects: Applied sciences; Exact sciences and technology; Metals. Metallurgy; Nickel base alloys; Point defects; Intermetallic compound; Point defect; Site preference; Nickel Aluminides; Aluminium alloy; Alloying element; First-principle electron theory
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2005.10.039

First-principles supercell calculations were performed to predict the site preference of Pt, Hf, Cr and Ir in L12 Ni3Al. Our calculations showed that, at T = 0 K, Pt always prefers Ni sites, while Cr and Hf always prefer Al sites in Ni3A1. 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.