Phase transformation induced plasticity in high-strength hexagonal close packed Co with stacking faults

RZ Su and D Neffati and JH Cho and Q Li and J Ding and HY Wang and Y Kulkarni and XH Zhang, SCRIPTA MATERIALIA, 173, 32-36 (2019).

DOI: 10.1016/j.scriptamat.2019.07.030

Deformation twinning and dislocation glide are two primary deformation mechanisms in hexagonal close packed (HCP) metals. Here we show, via in situ micropillar compression tests, that HCP Co pillars with high- density stacking faults exhibit a high yield strength and significant plasticity. Transmission electron microscopy studies reveal the formation of extensive face-centered cubic (FCC) Co phase after deformation. Molecular dynamics simulations confirm the deformation induced phase transformation, and shed light on the deformation mechanisms in HCP Co with pre-existing stacking faults. This study provides new insights into achieving high strength and plasticity in HCP metals via stacking faults and phase transformation. (C) 2019 Acta Materialia Inc Published by Elsevier Ltd. All rights reserved.

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