Microstructure and dislocation density of AlCoCrFeNiSix high entropy alloy coatings by laser cladding

•AlCoCrFeNiSix high-entropy alloy coatings on AISI 304 stainless steel were synthesized by laser cladding.•Nano-sized precipitates with spherical shape are found in the coatings.•The influence of Si element on dislocation densities is explored in detail.•Dislocation strengthening is confirmed as the primary strengthening mechanism of the coatings. AlCoCrFeNiSix high-entropy alloy coatings were synthesized by laser cladding. The effect of Si element on the phase constitution, microstructure, and microhardness of the coating was investigated. The results show that the main phase in the coatings are disordered solid solution with a body-center cubic (BCC) structure. A small quantity of nano-sized precipitates of ordered BCC AlNi phase are distributed in the grain. The dislocation density and the microhardness increase linearly with the increase of the Si content. The improvement of the microhardness is due to the solid-solution strengthening, precipitation strengthening, and dislocation strengthening, and the quantitative analysis reveals that dislocation strengthening plays a dominant role.