Dynamic recrystallization in face-centered cubic particles during high- velocity impacts

DF Rojas and M Isiet and M Ponga, MECHANICS OF MATERIALS, 168, 104268 (2022).

DOI: 10.1016/j.mechmat.2022.104268

In this work, dynamic recrystallization of nano-and micro-particles is investigated with high-velocity impact simulations. Molecular dynamics simulations reveal that upon a critical velocity, face-centered cubic particles recrystallize due to a synchronous emission of Shockley partial dislocations. Dislocations interaction generates a complex network, ultimately leading to recrystallization of high misorientation angle grains. Since pressure wave decays with the distance from the impacted surface, so does the grain size, generating a new microstructure with spatial gradients within the particles. We show that this behavior is universal for a set of six representative face-centered cubic materials. Below the critical velocity, twinning dominates the deformation mechanisms. The atomistic results are then extrapolated to microscopic size particles relevant in the context of some additive manufacturing techniques using a continuum dislocation density model. The severe plastic deformation experienced by the microparticles results in large dislocation densities and recrystallized grains of varying sizes. These findings are then compared with experimental observations of previous reported microparticles impacts, finding good agreements between experiments and simulations. Our work provides a quantitative analysis of the dynamic recrystallization of particles during high- impact velocities. It also suggests the possibility of tailoring their microstructure by controlling their size, orientation, and impact velocity.

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