Effect of Y2 O3 nanoparticles on powder plasma arc additive manufacturing of CoCrFeNiMn high-entropy alloys: Microstructure evolution and mechanical properties

This study focuses on the fabrication of an oxide dispersion strengthened CoCrFeNiMn high-entropy alloy (HEA) through powder plasma arc additive manufacturing. The impact of varying concentrations of Y2O3 (0 at%, 0.5 at %, and 1.0 at%) on the tensile properties of the CoCrFeNiMn HEA at 300 degrees C was analyzed, and the microstructure and post-tensile fracture morphology was observed. The tensile results showed that the ultimate tensile strength of the specimens containing 0.5 at% Y2O3 increased by 19.07% from 323.33 MPa to 385.00 MPa as compared to the specimens without Y2O3. The elongation rate increased from 17.97% to 26.63%. This strengthening effect is due to smaller grain size and increased dislocation density. The microstructure shows that the grain size of the specimen with 0.5 at% Y2O3 is reduced to 107.69 mu m compared to 119.79 mu m for the specimen without Y2O3. Additionally, the specimen with 0.5 at% Y2O3 exhibits a more pronounced <101> orientation in comparison to the specimen lacking Y2O3. The <101> orientation results in a greater density of geometrically necessary dislocations, thereby enhancing the strength of the specimens relative to the <001> orientation typically observed in face-centered cubic HEAs. This study demonstrates the potential for ODS HEA additive manufacturing through the blending of micron and nanoscale powders.