The electronic mechanism of the γ/γ′ interface strength of Ir-based alloys

The electronic structures of the gamma/gamma' interface for two-phase Ir-based alloys (Ir/Ir3Ta and Ir/Ir3Ti) have been investigated by performing first-principles quantum mechanics DMol3 (a type of density functional theory for molecules) calculations. The Mayer bond order (MBO) is used to represent the shear and cohesion strengths of the interface by a local sum of the horizontal and vertical MBOs. By comparison with those for single-crystal Ir, the results show that both the cohesive and shear strengths of the gamma/gamma' interface for the Ir/Ir3Ta alloy increase. The cohesive strength of the interface for the Ir/Ir3Ti alloy increases, whereas the shear strength of the interface for Ir/Ir3Ti decreases. The electron charge density, the Hirshfeld charge, and orbital charge transfers are also calculated and analysed. An electronic mechanism for the gamma/gamma' interface strength of Ir-based alloys is then suggested.