Stabilized sub-grain and nano carbides-driven 1.2GPa grade ultra-strong CrMnFeCoNi high-entropy alloy additively manufactured by laser powder bed fusion

High-entropy alloys (HEAs) with interstitial atoms that are produced by additive manufacturing have gained intensive interest in the materials science community because of their suitability for constructing high-strength net-shape components. Here, a strategy to additionally enhance the strength of selective laser melted carbon-containing HEAs was investigated. The as-built carbon-containing HEAs (C-x(Cr20Mn20Fe20Co20Ni20)(100-x) (x = 0.5 at.%, 1.0 at.%, and 1.5 at.%)) contain supersaturated carbon, and the extent of supersaturation increases as the carbon content increases. When subjected to aging treatment at 650 degrees C for 1 h, the microstructure of the three alloys did not change at the grain scale. However, the microstructure at the sub-grain scale changed markedly, and these changes influenced the tensile properties and deformation mechanism. In particular, the tensile strength of aged 1.5C-HEA at 650 degrees C was similar to 1.2 GPa at room temperature, which is higher than those reported for CrMnFeCoNi HEAs. Furthermore, the main deformation mechanism changed from deformation twinning to dislocation-mediated slip, resulting in much higher strain hardening capacity after the aging treatment. This work led to the development of an alternative promising method that involves tailoring the microstructure, to enhance the mechanical properties of additively manufactured metallic materials that contain interstitial atoms. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

This study investigated a strategy to enhance the strength of selective laser melted carbon-containing high-entropy alloys through microstructure control. After aging treatment, the tensile strength and deformation mechanism of the alloys changed significantly, showing higher strain hardening capacity.