Laser metal deposition of CoCrFeNi(SiC)x high-entropy alloys: microstructure and mechanical properties

This study explores the use of silicon carbide to strengthen CoCrFeNi high-entropy alloys (HEAs) with face-centered cubic structure. CoCrFeNi(SiC)x (x = 0, 0.1, 0.2, and 0.3) HEAs were prepared through laser metal deposition. The effects of different contents of SiC particles on the microstructure and mechanical properties of CoCrFeNi HEA were investigated. The results indicate that the addition of SiC particles led to the formation of the Cr7C3 phase, which refined the grain size and shifted the grain orientation from <001> to <101>. With the further addition of SiC, the amount of Cr7C3 phase increased, and β-SiC particles appeared. The Cr7C3 phase increased the average hardness of specimens from 191.71 HV to 403.86 HV. Tensile tests showed that the 10 at.% SiC specimens exhibited a yield strength of 534.00 MPa, an ultimate tensile strength of 799.67 MPa, and an elongation of 8.17%, hence optimizing the combination of ultimate tensile strength and elongation. The improvement in mechanical properties is mainly attributed to the refinement of grain boundaries and enhancement of dislocation density.