First principles study of effect of lattice misfit on the bonding strength of Ni/Ni3Al interface

摘要

By using a discrete variational Xα (DV-Xα) method, the electronic structures and bonding strengths of Ni/Ni3Al (or γ/γ′) interface with different lattice misfits (δ) were calculated in the framework of the nonrelativistic first-principles theory. In order to describe the effect of δ on the interfacial binding strength and the structural stability of coherent γ/γ′ interface, we calculated the interfacial binding covalent bond density (CBD) and the local environmental total bond overlap population (LTBOP). Very obvious effects of lattice misfits on the electronic structures of coherent γ/γ′ interface were found. On one hand, less than −0.6% negative lattice misfit can increase the binding strength of the γ/γ' interface. On the other hand, the local environmental total bonding strength of the γ/γ' interface decreases with increasing magnitude of δ. Therefore, the magnitude and sign of lattice misfit must be carefully controlled to balance the high-temperature creep strength of Ni-base single crystal superalloy and the structural stability of the γ/γ' interface when one designs new alloys.