Tensile properties and fracture mechanism of the Ti2AlC(0001)/TiAl(111) interface: Insights from a first-principles study

Abstract

A combination of three methods, Griffith theory, work of interface separation, and first-principles tensile simulations, has been applied to uncover the Ti2AlC/TiAl interface's tensile properties and fracture mechanisms. The results show that the three methods give consistent fracture locations when considering the interface elastic energy for work of interface separation, i.e., C-hcp-hollow-BCA fractures inside the TiAl bulk, while Al-fcc-hollow-ACB, Ti(C)-hcp-hollow-ABC, and Ti(Al)-hcp-hollow-BAC all fracture at the interface; Ti(C)-hcp-hollow-ABC has a maximum critical strain (20 %) and the strongest ideal tensile strength (29.32 GPa), because it has a greater deformation energy at the inflection point and it doesn't fracture when Ti(Al)-hcp-hollow-BAC is fully fractured, and the PDOS shape of the interface's Ti atoms exhibits a higher degree of consistency during the tensile process, and the C atoms of the Ti2AlC-2 layer in the Ti(C)-hcp-hollow-ABC exert a strong influence on the Ti atoms at the interface; the fracture mechanism of the Ti2AlC/TiAl interface structure includes the formation of electron holes, the holes increasing, the formation of microcracks, microcracks increasing, the formation of electron depletion region due to a sharp increase in the bond length and the interlayer spacing, followed by a complete fracture.