Precipitate strengthening in nanocrystalline Ti/Ta composites

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.