Effect of Al Addition on the Microstructural Evolution of Equiatomic CoCrFeMnNi Alloy
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The present investigation reports the effect of aluminum addition on the microstructural evolution in the equiatomic CoCrFeMnNi high-entropy alloy. Aluminum was added to the alloy in varying quantity (0 ≤ Al ≤ 10 at.%) using the vacuum arc melting technique, and phase formation was probed using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results indicate that the FCC phase in the alloy remains unaltered up to Al of 5 at.%. The higher amount of Al addition leads to the precipitation of B2 Al(Ni, Cr, Fe, Co, Mn) in the FCC matrix. For Al ≥ 7%, typical phase-separated microstructure consisting of FCC, and B2 phases have been observed. The microstructural changes lead to hardness variation from 1.3 to 2.2 GPa, mainly due to precipitation and solute solution hardening of FCC phase. For FCC phase, Al atoms being larger in size can lead to lattice distortion and improve yield strength. The results have been explained by detailed thermodynamic analysis using HEA3 database.
KeywordsHigh-entropy alloy Cantor alloy Microstructure TEM
The authors would like to thank Mr. Niraj Nayan from VSSC, Indian Space Research Organization (ISRO) for technical assistance. The authors would like to acknowledge the funding received from ISRO under Respond scheme and Science and Engineering Research Board (SERB) of Department of Science and Technology (DST).
Funding provided by Science and Engineering Research Board and Indian Space Research Organization is duly acknowledged.
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