Additive manufacturing of CoCrFeNiMo eutectic high entropy alloy: Microstructure and mechanical properties

The CoCrFeNiMo eutectic high entropy alloy (EHEA) was fabricated successfully by directed energy deposition (DED). The microstructure and mechanical properties of the CoCrFeNiMo EHEA samples were investigated in this work. Interestingly, the different microstructure morphology and phase composition were shown from bottom to top along the building direction. The seaweed eutectic structure, herringbone like hierarchical eutectic structure and irregular lamellar structure were observed at the top, middle and bottom parts, respectively, which was due to changes in temperature gradients caused by increasing deposition height. The dominant phases in the CoCrFeNiMo EHEA samples were FCC, Sigma and mu phases. The FCC phase alternated with the Sigma phase, and mu phase particles were precipitated from the fringes of the Sigma phase. Moreover, the CoCrFeNiMo EHEA samples by DED achieved high hardness (658.44 HV) and high wear resistance (the friction coefficient (COF) is 0.586), which were guaranteed by the intermetallic compounds and fine eutectic lamellar structure.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The CoCrFeNiMo eutectic high entropy alloy (EHEA) was successfully fabricated using directed energy deposition (DED). The microstructure and mechanical properties of the CoCrFeNiMo EHEA samples were investigated, revealing different structure morphologies and phase compositions along the building direction. The dominant phases in the samples were FCC, Sigma, and mu phases, with FCC and Sigma phases alternating and mu phase particles precipitating from the fringes of the Sigma phase. The DED-produced CoCrFeNiMo EHEA samples exhibited high hardness and wear resistance due to the intermetallic compounds and fine eutectic lamellar structure.