Phase formation and mechanical analysis of sintered Ni25Al25Co15Fe15Mn8Ti7Cr5 high entropy alloy

Abstract

In recent years, the pursuit of cutting-edge materials has intensified, with a focus on affordability, lightweight characteristics, and exceptional performance under high-temperature conditions, to serve as alternatives to Ni-base superalloys and other conventional alloys. Potential materials suitable for high-temperature structural applications with lightweight characteristics are intermetallics such as NiAl, and TiAl, but pose numerous fabrication challenges and poor ductility behaviour at room temperature. In view of this, a novel Ni₂₅Al₂₅Co₁₅Fe₁₅ Mn₈Ti₇Cr₅ high entropy alloy (HEA) was fabricated using spark plasma sintering (SPS). The alloy was developed at a sintering temperature of 850 °C, a heating rate of 90 °C/min, a pressure of 50 MPa, and a dwelling time of 5 min. X-ray diffraction, scanning electron microscopy, and Vickers hardness tester were used to investigate the phase formation, microstructure, and mechanical properties of the HEA, respectively. The microstructure of the sintered HEA shows a homogenous dispersion of the alloying metals. The sintered microstructures showed a mixture of simple and complex phases. The grain size analysis shows that the sintered HEA exhibited a lower grain size of 2.28 µm and a refined crystallite size of 3.159 µm. The microhardness value and relative density of the sintered HEA are 135.8 HV and 99.56 %, respectively.