Interfacial segregation and fracture in Mg-based binary alloys: Experimental and first-principles perspective

We investigated the effect of solute elements on interfacial segregation and fracture in Mg alloys by first-principles density functional theory calculations in conjunction with both experiment and interfacial fracture mechanics. Based on the assumption of brittle fracture in Mg alloys, the interfacial separation caused by segregated solutes in Mg can be efficiently described by the energy-based criterion of fracture, which is in good agreement with the fracture toughness obtained by experimental tests of Mg-M binary alloys. The electronic interaction-that is, the change in the electronic state between the interface and surface-mainly influences the ideal work of separation regardless of the type of interface. We found that IIIB (d(1)) and IVB (d(2)) solutes, such as Zr, show distinctive hybridization between the p band of Mg and the d band of the solute, which characterizes the strong fracture toughness of Zr-doped Mg alloys in both the calculations and experiments. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.