Investigation of Mechanical Properties and Wear Resistance of A2/B2 Type Medium-Entropy Alloy Matrix Reinforced with Tungsten Particles by In-Situ Reaction

Microstructure, mechanical properties, wear resistance, corrosion and corrosive wear resistance of AlCrFeNiWx (x = 0, 0.1, 0.2, 0.3 and 0.4) medium-entropy alloys (MEAs) prepared by vacuum arc melting process were investigated. Results of the study show that the microstructure of as-cast AlCrFeNiWx alloys is composed of one disordered Fe-Cr rich BCC phase (A2) and one ordered NiAl-rich (B2) phase when x = 0 and 0.1; W particles appear when x >= 0.2. Hardness and strength of AlCrFeNi alloy are markedly increased by the W addition. The strengthening mechanisms include solid-solution strengthening, nano-sized precipitation strengthening and second phase strengthening. The excellent ductility of AlCrFeNi is retained with minor W addition (x <= 0.2) but it considerably declines as more W is added, resulting from the precipitation of excessive large-sized W particles. W addition improves the pitting resistance and passivation property of AlCrFeNi HEA in 3.5 wt. % NaCl solution. It is shown that AlCrFeNiW0.3 possesses the highest corrosion resistance, as reflected by the highest E-corr and the lowest I-corr. Tungsten notably enhances the resistance of this HEA to wear and corrosive wear. AlCrFeNiW0.4 with the highest strength and hardness exhibits the lowest wear volume loss under both dry and corrosive wear conditions.