Interfaces Between Al₂O₃ and β-Ni_1-xAl_x Alloys: Complex Structures and Ab Initio Thermodynamics

A methodology to study the structural stability of binary alloy/Al₂O₃ interfaces is developed by expanding the conventional ab initio thermodynamics to include the dependence on alloy composition. Results on β-Ni_1-xAl_x/Al₂O₃ interfaces predict the existence of two types of stable interfaces. The stable interface at equilibrium with Al-rich or strictly 1∶1 alloy contains an Al₂-terminated Al₂O₃ surface and continues with NiAl layers, and the interface at equilibrium with Ni-rich alloy has Al accumulation but continues with a Ni-rich and then NiAl layers. Works of separation for the two interfaces are close to each other.