Microstructure and Mechanical Properties of CoCrFeNi Ti-Al High Entropy Alloys

Year 2020, Volume: 7 Issue: 2, 157 - 162, 26.06.2020

Ilkay Kalay

https://doi.org/10.17350/HJSE19030000184

Cited By: 2

Abstract

The structure and mechanical properties of CoCrFeNi and CoCrFeNiTi0.5Al0.5 in molar ratio high entropy alloys were investigated using X-ray diffraction XRD , optical microscope OM , scanning electron microscope SEM , hardness and compression tests. With the addition of Ti and Al, the crystal structure of CoCrFeNi changed from FCC to a mixture of FCC and double BCC structures. The lattice parameter of FCC increases upon addition of Al and Ti. The microstructure analysis shows the morphological transition of dendrites from non-equiaxed to equiaxed during the suction casting of CoCrFeNiTi0.5Al0.5 alloy. The Vickers microhardness testing of CoCr-FeNi alloy reveals significant increase in hardness with the addition of Al and Ti. The hardness values are improved in as-suction cast CoCrFeNi and CoCrFeNiTi0.5Al 0.5 alloys compared to their ascast alloys due to strengthening. The CoCrFeNiTi0.5Al0.5 alloy yields at 1997 MPa and fails at 2344 MPa. The fracture mechanism of CoCrFeNiTi0.5Al 0.5 alloy reveals a cleavage mode.

Keywords

High entropy alloys, Microstructure, Microhardness, Compression test, Metallic alloys

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