Microstructure control and corrosion properties of AlCoCrFeNiTi _0.5 high-entropy alloy

The microstructures, hardness and electrochemical properties of AlCoCrFeNiTi _0.5 high-entropy alloys fabricated by cold crucible levitation melting (CCLM) with as-cast structure and tempering treated structures were investigated. The results show that in contrast to suction casting using copper molds, CCLM causes the growth of dendrite phase and separation of ω phase. As the increase of temperature, the dendrite grains grow up, the amount of eutectic structures increases, and the intensity of BCC peak shows a rising trend after the first drop. At the temperature of 800°C, the dendrite grains become refined. And then, as the temperature increases, the element segregation of interdendrite is weakened. The alloy exhibits a superior resistance to tempering and softening property. Furthermore, pitting corrosions are mainly concentrated in the place between dendrite phase and eutectic α phase. The tempering treatment improves corrosion properties in a 3.5% NaCl solution, and the alloy tempered at 700 exhibits the best corrosion property among the experimental alloys. Copyright