Effect of element distribution on the microstructure of FeCoCrNi high entropy alloy coating

Laser cladding of FeCoCrNi high entropy alloy coating on the surface of 6 mm thick TC4 titanium plate was studied by focusing on the surface strengthening technology of laser cladding high entropy alloy. Firstly, the phase analysis of the FeCoCrNi high entropy alloy cladding layer was carried out by X-ray diffraction to explore its phase composition. Then, the microstructure and phase distribution of the cladding layer and its interface with TC4 substrate were investigated by metallographical microscope and field emission scanning electron microscope. The results show that Ti and Ni, Ti and Co have the most significant negative mixing enthalpy (∆H_mix), so it is easy to cause the enrichment of (Ti, Ni, Co) in some phases, and the enrichment of (Fe, Cr) in the surrounding phases. The upper and lower part of the bonding interface is mainly composed of gray columnar grains, and the middle part is mainly composed of white reticulum structure and gray shrinkage cavity.