Atomistic simulation of the tension/compression response of textured nanocrystalline HCP Zr

Abstract

Molecular dynamics virtual tension/compression tests were performed to study the deformation mechanisms in nanocrystalline (15–38 nm grain size) 50 grains HCP Zr columnar samples with random [1 −1 0 0] prismatic and [0 0 0 1] basal textures. Two different embedded atom potentials were used to model atomic interactions and to describe the relationship between generalized stacking fault energies and mechanical predictions. Both potentials predict higher flow stresses in compression for both textures. Nanocrystalline Zr [0 0 0 1] basal textured samples deform mainly by dislocations emission and glide along 〈1 1 −2 0〉 {1 −1 0 0} and by grain boundary sliding and migration; both potentials show the same deformation mechanisms for this texture. Prism [1 −1 0 0] textured samples deform mainly by twinning. Both in tensile and compression tests {1 1 −2 1} twins nucleate mainly at grain boundaries and sites with high stress concentration. These twins grow by a shuffle mechanism. Emission and sliding of partial dislocations, grain boundary gliding and migration were also observed for this texture with the main dislocations being of the 1/3 〈1 −2 1 0〉 type. These basic deformation mechanisms were the same for both potentials tested. The observed quantitative differences between the predictions of both potentials are discussed in terms of some of their basic properties.