Improved microstructure and mechanical properties of ODS-CoCrFeNiMn high entropy alloys by different Ti, Zr and Y2O3 addition

Four ODS-CoCrFeNiMn high entropy alloys (HEAs) with different Ti/Zr/Y2O3 addition were produced by powder metallurgy. The role of Ti, Zr, Y2O3 on improving microstructure and mechanical properties of ODS-CoCrFeNiMn HEAs was studied. The type of nanoscale oxides is effectively changed from Y2O3 (1Y alloy), Y2TiO5, YTiO3 and Y2Ti2O7 (1YT), Y4Zr3O12 and Y2Zr2O7 (1YZ) to YTiO3, Y2TiO5, Y2Ti2O7, Ti2O3 (1YTZ) by introducing different addition. The joint addition of Ti, Zr and Y2O3 in 1YTZ has the most significant refinement on grain size and increases number density of nanoscale oxides, which reach 130 nm and 2.01 × 1021/m3, respectively. The well refined grains and high density of nanoscale oxides in 1YTZ alloy lead to the highest hardness and compressive yield strength, which are 449 HV and 1309 MPa, respectively. The different formation mechanisms of nanoscale oxides due to different addition and its influence on mechanical properties in ODS-CoCrFeNiMn HEAs are disclosed.