Role of thermal expansion and redistribution of components on the temperature dependence of the lattice misfit in γ/γ′ superalloys

The relative role of thermal expansion and redistribution of alloy components in the temperature dependence of the lattice misfit in γ/γ′ alloys is investigated on the basis of ab initio calculations. We show that in a wide temperature region up to approximately 0.6-T_melt, the lattice misfit is determined by the difference in thermal expansion of γ and γ′ phases and shows only a slight variation. For higher temperatures the redistribution of the major alloy components between the phases becomes a leading contribution to the lattice misfit.