Superior strength-ductility synergy of an oxide-dispersion strengthened CoCrNi-based multi-principal element alloy

Abstract

CoCrNi-based multi-principal element alloys (MPEAs) often lack strength at elevated temperatures. Here, to overcome this deficiency, a novel oxide-dispersion strengthening (ODS) CoCrNi-based MPEA was designed by incorporating nano-scale yttria via LPBF. The ODS MPEA possesses superior strength-ductility synergy at both ambient and elevated temperatures to most reported CoCrNi-based MPEAs and state-of-the-art superalloys. TEM investigations revealed dislocation forest and slip traces in the interior of solidification dislocation cell structure, along with extended stacking faults and nano-twins. These features contributed to the excellent strength-ductility of the MPEA. Lastly, quantitative analyses uncovered the contributions of operating strengthening mechanisms to its high strength.

Keywords

• Multi-principal element alloy (MPEA)
• Oxide-dispersion strengthening (ODS)
• Transmission electron microscopy (TEM)
• Dislocation
• Laser powder bed fusion (LPBF)