Molecular dynamics simulations of the tensile responses and fracture mechanisms of Ti2AlN/TiAl composite
XL Han and P Liu and DL Sun and Q Wang, THEORETICAL AND APPLIED FRACTURE MECHANICS, 101, 217-223 (2019).
In the present work, molecular dynamics simulations are carried out to investigate the tensile responses and fracture mechanisms of Ti2AlN/TiAl composite. It is found that the Ti2AlN/TiAl composite with different interface atomic structure shows significantly different tensile responses and fracture mechanisms. When the tensile loading is applied normal to the Ti2AlN(0 0 1)/TiAl(1 1 1) coherent interface, the micro- void would nucleate from the interface, rapidly propagate along the interface and evolve into the complete-crack, leading to the brittle fracture behavior of Ti2AlN/TiAl composite. The formation of stress concentration and Lomer-Cottrell lock in the misfit dislocations at the coherent interface is the major mechanism for the nucleation of micro- void. When the tensile loading is applied normal to the Ti2AlN(1 0 (1) over bar 3)/TiAl(1 1 1) incoherent interface, micro-voids can nucleate from the weak interactive regions at the incoherent interface, but they cannot propagate rapidly along the incoherent interface, which indicates that the Ti2AlN(1 0 (1) over bar 3)/TiAl(1 1 1) incoherent interface system shows ductile fracture behavior. The ductile fracture mechanism is twofold: firstly, the dislocations in Ti2AlN and TiAl slab can nucleate at the tip of micro-crack and effectively blunt the propagation of micro-crack along the incoherent interface; secondly, the strong N-Ti and N-Al bonds at the incoherent interface can give a contribution to the overall stability of Ti2AlN(1 0 (1) over bar 3)/TiAl(1 1 1) incoherent interface.
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