Abstract: In this work, we coated a layer of Y₂O₃ particles in Hastelloy X (HX) nickel-based superalloy powder by in situ chemical method and combined with laser powder bed fusion (LPBF) technology to develop a high-performance Y₂O₃-doping alloy, designated as Y-HX. The results show that the doping of Y₂O₃ particles prevents crack formation during the printing process and reduces solute segregation at cell and grain boundaries by increasing the viscosity of the molten pool. The doping of Y₂O₃ particles to the printed Y-HX alloy enhances grain boundary characteristics, transforming coarse sheet-like carbides into finely dispersed granular carbides at the boundaries during subsequent heat treatment. Additionally, doping with Y₂O₃ particles increases the recrystallization activation energy of the Y-HX alloy from 149.4 to 278.8 kJ mol^-1. At 750 °C, the Y-HX alloy exhibits an ultimate tensile strength of 619 ± 2 MPa and an elongation of 52 % ± 2 %, along with an ultimate tensile strength of 325 ± 3 MPa and an elongation of 47 % ± 2 % at 900 °C. Our work provides a promising way to develop additive-manufactured superalloys with exceptional thermal stability and remarkable high-temperature mechanical properties.

Key words: Laser powder bed fusion, Nickel-based superalloy, Y₂ O₃ coating carbides, High temperature mechanical properties