Effect of Annealing Temperature on Microstructure and Properties of Al_xTi_xNi_xCoCrCu_0.5FeMo High Entropy Alloy Coating

Al_xTi_xNi_xCoCrCu_0.5FeMo (x=4, 5, 6, 7, 8, 9, molar ratio) high-entropy alloy coating was laser cladded on the surface of 40Cr steel and annealed at 300-900℃. The effect of annealing temperature on the microstructure and properties of the coating was studied. The results show that both unannealed and 300℃ annealed high-entropy alloy coatings had a single body-centered cubic (BCC) phase structure, and Al₂Ti₃-like intermetallic compound phase was formed in the alloy coatings after annealing at 500-900℃. When the annealing temperature increased to 500℃, the intragranular corrosion resistance became poor, and the corrosion resistance of the coating decreased with increasing annealing temperature. With increasing annealing temperature, the hardness of the high-entropy alloy coating first decreased, then increased and then decreased. The Al₄Ti₄Ni₄CoCrCu_0.5FeMo alloy annealed at 700℃ had the highest hardness, which was 1 019 HV.