First-principles calculations of the elastic constants of Fe–Pt alloys

A first-principles study of the elastic constants of ordered Fe–Pt alloys (cubic Fe3Pt, tetragonal FePt and cubic FePt3) as well as bcc Fe, fcc Pt and fcc Pd as reference materials was carried out. The calculations were performed within the density functional theory in the generalized gradient approximation (GGA) using the projector augmented-wave (PAW) method. Using Reuss–Voigt–Hill (RVH) averages, the isotropic shear modulus (GRVH), Poisson's ratio (ν) and Young's modulus (E) of the corresponding polycrystalline materials were estimated from the calculated single-crystal elastic constants. A non-linear compositional dependence for c′ and c44 as well as GRVH and E is observed as a function of the Pt concentration.