SYNTHESIS OF LASER HIGH ENTROPY ALLOYING COATING ON THE SURFACE OF SINGLE-ELEMENT Fe BASE ALLOY

FeCoCrAlCu laser high entropy alloying coating has been synthetized by high power semiconductor laser alloying of equimolar ratio of Co, Cr, Al, Cu four elements mixture powder on the surface of single-element Fe base alloy Q235 steel. The microstructure, constituent phases, composition distribution and mechanical properties of FeCoCrAlCu laser high entropy alloying coating were investigated by SEM, XRD, EDS and microhardness tester. Experimental results show that the principal element of Fe in the single-element base alloy Q235 substrate participates surface alloying process during the laser irradiation, forming FeCoCrAlCu five principal high entropy alloy coating. The alloying coating is composed of simple bcc solid solution and the microstructure is mainly composed of typical dendritic structure. Intermediate phase sigma with tetragonal structure merely appears near the interface between laser alloying coating and substrate. From the surface of high entropy alloying coating to substrate, it presents the gradual distribution of the mixing entropy from high entropy, medium entropy to low entropy. the microhardness of FeCoCrAlCu laser high entropy alloying coating reaches 8.3 GPa, which is three times as much as that of the Q235 substrate.