First-principle investigation of 3d transition metal elements in γ′-Co3(Al, W)

The alloying effect of 3d transition metal elements on the lattice constants and their site preferences in gamma'-Co-3(Al, W) are systematically studied based on a supercell model. The lattice constant of the gamma' phase is modified by the addition of 3d transition metal elements, and it increases in the order of Fe < Ni < Mn < Cr < V < Ti. Four types of site preference are identified for these 3d elements in gamma' phase by analyzing the binding energy and the impurity formation energy. Ni, Fe, V, and Ti are recognized to stabilize the gamma' phase. Their distinct alloying effect is further revealed by investigating the impurity-induced charge density difference and the partial density of states. These results are in agreement with the experimental data ever reported. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3319650]