Enhanced mechanical properties of dispersed carbide-strengthened CrFeNi-based medium entropy alloys prepared via powder metallurgy

Abstract

In this study, a set of CrFeNi -based medium-entropy alloys (MEAs) with varying carbon contents were prepared by spark plasm sintering (SPS) using atomized alloy powders as raw material. The microstructures of powders and as-sintered alloys were characterized using ECCI and EBSD. The mechanical properties of as-sintered alloys were tested and the strengthening mechanical were discussed. The results showed that the microstructures of the CrFeNi gas atomized powder and sintered alloy were both single FCC phase in an equiaxed state. However, the matrix grains of powder with carbon addition were mostly dendritic, and few eutectic carbides could be observed between matrix grains. Compared with the CrFeNi MEA, the addition of 8 at. % C led to an increase in the yield strength and tensile strength from 395 MPa to 630 MPa–590 MPa and 990 MPa, respectively. Orowan strengthening and grain refinement resulting micro/nano carbides are responsible for the improvement in mechanical properties.

Keywords

• Second phase strengthening
• Atomized alloy powders
• Medium-entropy alloys
• Carbides