Fabrication of a strong and ductile FeCoCrNiMo0.3 high-entropy alloy with a micro-nano precipitate framework via laser powder bed fusion

Practical engineering applications of high-entropy alloys (HEAs) are limited owing to the trade-off between their strength and plasticity. To address this limitation, herein, a FeCoCrNiMo0.3 HEA with a novel micro-nano rod-shaped σ-phase framework was fabricated via laser powder bed fusion (LPBF). The high cooling rate during the LPBF process, combined with the synergistic effects of large aspect ratios and high growth rates of subgrains, create favorable conditions for the formation of micro-nano precipitation frameworks. This micro-nano precipitate framework introduced a directional constraint mechanism on deformation, thereby simultaneously increasing the strength and plasticity. The fabricated HEA exhibited considerably higher strength and plasticity than the most widely studied LPBF-FeCoCrNi HEA with common columnar grains, with a 30.9% increase in strength and 58.4% increase in ductility achieved. Furthermore, the strength-ductility trade-off has been overcome, and the strength-ductility synergy of the fabricated sample were better than those of other existing LPBF-HEAs. Our results can serve as reference guidelines for the preparation of HEAs with high strength and plasticity, which broaden the application prospects of LPBF-HEAs. •FeCoCrNiMo0.3 HEA with a novel micro-nano precipitate framework was fabricated via LPBF.•Strength and ductility increased significantly after Mo addition.•The strength-ductility synergy were considerably better than those of other LPBF-HEAs.•A directionally constrained deformation mechanism contributed to the improvement in mechanical properties.