Approach to obtain laser deposited CoCrFeNi alloy of uniform chemical composition with varying cooling rates on steel substrate and its characterization

In this study, a processing parameter, P/v, is proposed for laser deposition. This parameter is a function of laser power, P, and scan speed, v, and by keeping this process parameter constant, CoCrFeNi high entropy alloy is deposited on a stainless-steel substrate over a wide range of laser power and scan speed. An infrared pyrometer is used to measure the temperature of the molten pool during the depositions. These temperature readings were used to calculate the cooling rates of the molten pool, which were then correlated with the deposition properties. The depositions obtained had varying cooling rates with fairly uniform chemical composition. Phase analysis revealed a single phase across all depositions, with a change in the lattice parameter due to variations in cooling rate. Microstructure analysis shows various features throughout the entire deposition, with refinement of these features at higher cooling rates. Similarly, the hardness of the depositions increased with increasing cooling rate. This parametric approach in laser deposition enabled the study of the sole effect of cooling rate on changes in microstructure and mechanical properties, without any influence from changes in the alloying additives of the deposited material.