High-yttrium-content Hastelloy X fabricated by additive manufacturing: overcoming TCP phase-introduced embrittlement for enhanced creep resistance

Contrary to conventional approach that enhanced high-temperature creep performance by adding low levels of yttrium, in this work, we innovatively added a high content of Y (0.76 wt.%) to Hastelloy X and utilized laser powder bed fusion to form uniformly dispersed nano-sized Ni5Y phases at the cell boundaries. The Y-HX alloy exhibits sixfold longer creep rupture lifetime and lower minimum creep rate compared to the HX alloy at 750°C. The Ni5Y phase promotes Cr23C6 nucleation, forming chain-like Ni5Y-Cr23C6-σ precipitates, and mitigating embrittlement at medium temperature. Dense hexagonal dislocation networks at Ni5Y/matrix interfaces facilitate stress relaxation via cross-slip, preventing interfacial cracking.