CoCrFeNiMo_0.2 high entropy alloy by laser melting deposition: Prospective material for low temperature and corrosion resistant applications

In this paper, a Laser Metal Deposition (LMD) technique has been applied to fabricate CoCrFeNiMo_0.2 high-entropy alloys (HEAs). The microstructure, corrosion behavior and mechanical properties of LMD CoCrFeNiMo_0.2 HEAs prepared under different laser power have been investigated. It was observed that the laser power had significant effects on the columnar crystal morphology in LMD CoCrFeNiMo_0.2 HEAs. When increasing the laser power, the temperature gradient would decrease, leading to larger crystal size of columnar grains. The tensile properties at 293 K of the LMD CoCrFeNiMo_0.2 HEAs could be adjusted by changing the laser power, which was corresponded to the changes of microstructure. With a decrease in temperature from 293 K to 77 K, the tensile strength and tensile ductility of the LMD 1400 W CoCrFeNiMo_0.2 HEAs remarkably improved by ~70% and ~28%, to 928 MPa and 60%, respectively. In both 3.5 wt% NaCl solution and 1 mol/L H₂SO₄ solution, the CoCrFeNiMo_0.2 exhibited higher corrosion resistance than 304 stainless steel substrate, CoCrFeNi and even lower corrosion current density than 316L stainless steel.