Title

Excellent combination of compressive strength and ductility of (CoCrFeNi)x(Co0.26Cr0.07Fe0.16Ni0.31Hf0.4) high-entropy alloys

Publication Name

Materials and Design

Abstract

Instead of conventional CoCrFeNiHf high-entropy alloys (HEAs), we investigated the evolution of microstructure and compressive mechanical properties of (CoCrFeNi) (Co Cr Fe Ni Hf ) HEAs with varying x. Increasing x from 0.5 to 1.0, the microstructure changes from hyper-eutectic ones consisting of primary Laves phase and eutectic structure (x < 0.7), firstly to eutectic ones consisting of alternative FCC and Laves phase (x = 0.7 and 0.8), and finally to hypo-eutectic ones consisting of primary FCC phase and eutectic structure (x > 0.8). Interestingly, two different morphologies of eutectic microstructures are observed when x = 0.7 and 0.8 probably due to different fusion entropies of each phase. Increasing x from 0.5 to 1.0 reduces the yield strength from 1661 ± 64 to 688 ± 17 MPa but enhances the compressive ductility due to an increased fraction of soft FCC phase from ~0.39 to ~0.74. The second phase strengthening is the main strengthening mechanism. Importantly, when x = 0.9 and 1.0, these two alloys are not fractured when the strain reaches 0.5, one of which shows a large yield strength of 1028 ± 45 MPa (x = 0.9). Compared with conventional CoCrFeNiHf , the studied HEAs exhibit a much better combination of compressive strength and ductility. x x 0.26 0.07 0.16 0.31 0.4 x

Open Access Status

This publication may be available as open access

Volume

202

Article Number

109569

Funding Sponsor

Beijing Institute of Technology Research Fund Program for Young Scholars

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Link to publisher version (DOI)

http://dx.doi.org/10.1016/j.matdes.2021.109569