Effect of annealing-induced precipitation on the mechanical and wear properties of FeCoNiAl0.25Mn0.75Ti0.5 high-entropy alloy

This study investigates the effect of annealing on the microstructure, mechanical properties, and wear behavior of the FeCoNiAl0.25Mn0.75Ti0.5 high-entropy alloy. The as-cast alloy exhibits a dual-phase dendritic microstructure composed of FCC and BCC solid solutions. Annealing induces significant phase transformations. At 800 °C, nanoscale L1₂ precipitates form together with BCC precipitation within the FCC matrix, while fine FCC precipitates also appear in the BCC matrix. The L12 and BCC precipitates remain stable up to 1000 °C, whereas the FCC precipitates dissolve at this temperature. This precipitation–dissolution behavior strongly affects the mechanical and wear performance. Annealing significantly increases hardness and improves wear resistance, with a friction coefficient of 0.51, wear depth of 28.9 × 10-3 mm, and wear rate of 2.53 × 10-6 mm3/N·m. These improvements are attributed to precipitation strengthening and phase stability.