Effects of transition elements on the site preference, elastic properties and phase stability of L12 γ′-Co3(Al, W) from first-principles calculations

Abstract

We performed a systematic study of alloying effects on the site preference, elastic properties and phase stability of L12 γ′-Co3(Al, W) in terms of the first-principles calculations. Up to twenty-one transition metal elements (Sc, Ti, V, Cr, Mn, Fe, Ni, Y, Zr, Nb, Mo, Tc, Ru. Rh, Pd, Hf, Ta, Re, Os, Ir and Pt) were considered in this work. We find that Sc, Ti, V, Cr, Mn, Y, Zr, Nb, Mo, Tc, Hf, Ta, Re and Os favor to occupy the Al site, and Fe, Ni, Ru. Rh, Pd, Ir and Pt favor to occupy the Co site, except for Y, Fe and Ru, other transition metal elements can stabilize the L12 γ′-Co3(Al, W) at 0 K. By using stress-strain method, the elastic properties including bulk modulus, shear modulus and Young’s modulus were evaluated. It is verified that the elastic properties of L12 γ′-Co3(Al, W) depend on not only volume change but also electron density as well as electronic configurations. The thermodynamic results of phase stability of L12 γ′-Co3(Al, W) reveal that Hf, Ti and Ta are the promising alloying elements to improve the stability of L12 γ′-Co3(Al, W).