Role of tungsten on the microstructure and mechanical properties of novel NiMnCrMoWx high entropy alloys

Abstract

In this investigation, NiMnCrMoWx (x = 0.2, 0.4, 0.6, 0.8, and 1.0 at. fraction) high entropy alloys were prepared by the vacuum arc melting technique. The thermodynamic predictions were carried out to confirm the solid solubility and formation of various phases in these alloys. To understand the phase evolution and microstructure of the alloys, annealing at different temperatures was carried out. The X-ray diffraction results confirmed that the major phase formed was BCC along with minor FCC and some intermetallics in both the as-cast and annealed samples. The different microstructures were seen in the as-cast and annealed alloys consisting of dendritic, and equiaxed zones having bright, grey, and dark regions; annealing effectively altered the appearance of the phases in these regions. The hardness of the alloys increased up to NiMnCrMoW0.6 which contains a higher percentage of BCC1 along with intermetallics phases such as MnNi, MoNi3, and σ-phase. The compression and wear results were in good agreement with the hardness results. © 2024 Elsevier Ltd