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Open AccessArticle

In Situ Development and High Temperature Features of CoCrFeNi-M6Cp High Entropy-Alloy Based Hardmetal

by Huizhong Li 1,2,3, He Lin 1, Xiaopeng Liang 1,2,3,*, Weiwei He 4, Bin Liu 2, Yong Liu 2 and Li Wang 2,5,*
1
School of Materials Science and Engineering, Central South University, Changsha 410083, China
2
State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
3
Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China
4
Xi’an Sailong Metal Materials Co., Ltd., Xi’an 710016, China
5
Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Strasse 1, D-21502 Geesthacht, Germany
*
Authors to whom correspondence should be addressed.
Metals 2020, 10(3), 408; https://doi.org/10.3390/met10030408
Received: 24 February 2020 / Revised: 17 March 2020 / Accepted: 17 March 2020 / Published: 23 March 2020
In this work, an in-situ CoCrFeNi-M6Cp high entropy-alloy (HEA) based hardmetal with a composition of Co25Cr21Fe18Ni23Mo7Nb3WC2 was fabricated by the powder metallurgy (PM) method. Microstructures and mechanical properties of this HEA were characterized and analyzed. The results exhibit that this HEA possesses a two-phase microstructure consisting of the face-centered cubic (FCC) matrix phase and the carbide M6C phase. This HEA has an average grain size of 2.2 μm, and the mean size and volume fraction of carbide particles are 1.2 μm and 20%. The tensile tests show that the alloy has a yield strength of 573 MPa, ultimate tensile strength of 895 MPa and elongation of 5.5% at room temperature. The contributions from different strengthening mechanisms in this HEA were calculated. The grain boundary strengthening is the dominant strengthening mechanism, and the carbide particles are significant for the further enhancement of yield strength by the dislocation strengthening and Orowan strengthening. In addition, with increasing temperatures from 600 °C to 900 °C, the HEA shows a reduced yield strength (YS) from 473 MPa to 142 MPa, a decreased ultimate tensile strength (UTS) from 741 MPa to 165 MPa and an enhanced elongation from 10.5% to 31%. View Full-Text
Keywords: high entropy alloy; hardmetals; microstructure; tensile properties; strengthening mechanisms high entropy alloy; hardmetals; microstructure; tensile properties; strengthening mechanisms
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Li, H.; Lin, H.; Liang, X.; He, W.; Liu, B.; Liu, Y.; Wang, L. In Situ Development and High Temperature Features of CoCrFeNi-M6Cp High Entropy-Alloy Based Hardmetal. Metals 2020, 10, 408.

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