Effect of Annealing Temperature on Microstructure and Corrosion Resistance of NiCoCrMn High-Entropy Alloy Laser Cladding Coating

NiCoCrMn high-entropy alloy coating was prepared on the surface of 45 steel by laser cladding technique, and then annealed at different temperatures (700, 800, 900, 1000 ℃). The effect of annealing temperature on the microstructure and corrosion resistance of the laser cladding coating was studied. The results show that the as-deposited and annealed NiCoCrMn high-entropy alloy coatings had a single phase face centered cubic solid solution structure. The as-deposited, 700 ℃ annealed, and 800 ℃ annealed NiCoCrMn high-entropy alloy laser cladding coatings consisted of columnar grains, and inside grains a high population of cell substructures along with solidification segregation phenomenon existed. When the annealing temperature exceeded 900 ℃, solidification segregation phenomenon started to disappear. When the annealing temperature reached 1000 ℃, solidification segregation disappeared, and structive recovery and recrystallization occurred, resulting in formation of equiaxed microstructures. The annealing treatment improved the corrosion resistance of the cladding coating, and the corrosion resistance of cladding coating increased with increasing annealing temperature.