Mitigating elevated-temperature ductility loss in a LPBF-fabricated René77 superalloy via super-solvus heat-treatment

Laser-powder bed fusion (LPBF) fabricated high-performance superalloys (e.g. René 77) suffered from severe elevated-temperature ductility loss, which largely restricts their wide applications. This study showcases a super-solvus heat-treatment could mitigate the elevated-temperature embrittlement of LPBF René 77 at 850 °C. The LPBF alloy exhibits a 3.64-fold increase in fracture strain at 850 °C, achieving strength-ductility synergy superior to most reported superalloys. The enhanced ductility is found to stem from the synergistic effects of the super-solvus heat-treatment and unique microscale deformation features inherent to the superalloy. This study provides a simple yet effective strategy for overcoming elevated-temperature brittleness for high-performance LPBF superalloys.