The effect of cooling rate on the microstructure and mechanical properties of NiCoFeCrGa high-entropy alloy
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The effect of cooling rate on the microstructure and mechanical properties of equimolar NiCoFeCrGa high-entropy alloy (HEA) was studied by scanning electron microscopy, energy-dispersive X-ray spectroscopy and electron backscatter diffraction (EBSD), as well as by microhardness tests. Experimental results show that the cooling rate has a crucial impact on the developing microstructure which has a mixture of two—FCC and BCC—phases, leading to a self-similarity of the solidified structure formed in the sample. Furthermore, the cooling rate influences both the composition of the two phase-components and the ratio of their volume fractions, determining the mechanical properties of the sample. The present results confirm the grouping of Co, Fe and Cr in the FCC phase and that of Ni and Ga in BCC phase in the NiCoFeCrGa high-entropy alloy system. An empirical rule is suggested to predict how the phase-components can be expected in this complex high-entropy alloy.
Dalarna University, Regional Development Council of Dalarna, Regional Development Council of Gävleborg, County Administrative Board of Gävleborg, Swedish Steel Producers’ Association, Outokumpu Stainless and Sandviken City are thanked for financially supporting the research of DM. This research was partially supported by the Swedish Foundation for Strategic Research (SH), by the Hungarian–Russian Bilateral Research Program (TÉT) No. 2017-2.3.4-TÉT-RU-2017-00005, as well as by the Ministry of Human Capacities of Hungary within the Eötvös University Excellence Program (1783-3/2018/FEKUTSRAT).
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Conflict of interest
The authors declare that they have no conflict of interest.
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