Theoretical investigation of the Pt3Al ground state
H.R. Chauke, B. Minisini, R. Drautz, D. Nguyen-Manh, P.E. Ngoepe, D. G. Pettifor.
Intermetallics, 18, 417-421, (2010)
The deleterious low-temperature tetragonal phases in prototypical Pt-based superalloys have variously been reported as taking the tI16-U3Si (DOc), tI16-Ir3Si (DOc′) and tP16-Pt3Ga structure-types in contrast to the high-temperature cubic cP4-Cu3Au (L12) phase. We have investigated the relative stability of these four structure-types at absolute zero by using density functional theory. We find that the ground state of stoichiometric Pt3Al is tP16-Pt3Ga and that the other three lattices are mechanically unstable at absolute zero. Experiments are needed to measure the internal displacement parameters of these three competing tetragonal phases.
Keyword(s): Intermetallics; miscellanenous; alloy design; phase stability; predictions