Parametric study of spark plasma sintering of Al₂₀Cr₂₀Fe₂₅Ni₂₅Mn₁₀ high entropy alloy with improved microhardness and corrosion

Multicomponent Al₂₀Cr₂₀Fe₂₅Ni₂₅Mn₁₀ alloys were synthesized using spark plasma sintering at different temperatures (800, 900, and 1000°C) and holding times (4, 8, and 12 min) to develop a high entropy alloy (HEA). The characteristics of spark plasma-synthesized (SPSed) alloys were experimentally explored through investigation of microstructures, microhardness, and corrosion using scanning electron microscopy coupled with energy dispersive spectroscopy (EDS), Vickers microhardness tester, and potentiodynamic polarization, respectively. X-ray diffraction (XRD) characterization was employed to identify the phases formed on the developed alloys. The EDS results revealed that the alloys consisted of elements selected in this work irrespective of varying sintering parameters. The XRD, EDS, and scanning electron microscopy collectively provided evidence that the fabricated alloys were characterized by globular microstructures exhibiting face-centered cubic phase, which was formed on a basis of solid solution mechanism. This finding implies that the SPSed alloy showed the features of HEAs. The alloy produced at 1000°C and holding time of 12 min portrayed an optimal microhardness of HV 447.97, but the value decreased to HV 329.47 after heat treatment. The same alloy showed an outstanding corrosion resistance performance. The increase in temperature resulted in an Al₂₀Cr₂₀Fe₂₅Ni₂₅Mn₁₀ alloy with superior density, microhardness, and corrosion resistance over the other alloys developed at different parameters.