Precipitate strengthening in nanocrystalline Ti/Ta composites

J Li and SH Xu and FS Tan and Y Liu and QH Fang, PHILOSOPHICAL MAGAZINE LETTERS, 101, 115-122 (2021).

DOI: 10.1080/09500839.2020.1866220

Introducing precipitates significantly improves the strength of metallic materials. In the present study, we elucidate the role of a precipitated Ti phase on the deformation mechanism in nanocrystalline Ta through atomistic simulations and transmission electron microscopy characterisation. In particular, the Ti/Ta composites have a high yielding strength and flow stress compared to precipitation-free Ta. Especially, the forward stress in the hard Ti precipitate drives lattice rotation, which then increases further the strength and plasticity of the Ta/Ti composites. Furthermore, a large number of dislocations generated from the Ti precipitate result in a strong back stress in the soft Ta phase, which is consistent with our HRTEM observations.

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