Microstructure Of High-entropy Alloy Coatings Research Articles

Laser cladding [Cr–Fe4Co4Ni4]Cr2.6-xAlxMo0.4 high-entropy alloy coating to strong-acid erosion

Agitator blades made of 904 L stainless steel frequently underwent wear and erosion behavior in the phosphoric acid reactor. To improve the erosion resistance of 904 L steel, the composition of [Cr–Fe4Co4Ni4]Cr2.6-xAlxMo0.4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0, at.%) high entropy alloy (HEA) was designed by a cluster-plus-glue-atom model. The HEA coating was fabricated by laser cladding. The experimental results show that the HEA coating has good metallurgical bonding with the substrate. The phase of HEA coatings is mainly composed of FCC solid solution. The microstructure of HEA coatings is a typical dendrite structure. With the addition of Al, the hardness and wear resistance of HEA coatings are improved gradually. When x = 1.0, the microhardness of the coating can reach 332.6 HV0.2, which is 1.75 times than that of 904 L steel substrate. The wear volume (1.48 mm3) of the coating is almost half that of the substrate (2.62 mm3). When x = 0.8, the self-corrosion current density of the coating is about one-third of the substrate, and the impedance is increased by 3 times. Under the condition of solid particle erosion, the erosion mechanism of HEA coatings is the mixing of cutting-plowing and crater. Al0.8 coating has good erosion performance with the lowest erosion rate (0.028 mm3/h).