A novel nickel-based superalloy with excellent high temperature performance designed for laser additive manufacturing

Abstract

The nickel-based superalloys prepared by additive manufacturing (AM) commonly exhibit inferior mechanical properties at high temperatures, particularly in terms of ductility and creep resistance, compared to the corresponding conventional manufactured (CM)alloys, and this significantly hinders the widespread application of AM nickel-based superalloys in the aerospace industry. To address this problem, a novel nickel-based superalloy for additive manufacturing, Hastelloy X-AM (HX-AM), using the yttrium (Y) alloying strategy has been developed in this work. The results show that the Y element is present in the matrix as Ni5Y phase and yttrium oxide nanoparticles after laser additive manufacturing, exerting a significant inhibitory effect on the precipitation and coarsening of detrimental second phases at grain boundaries (GBs) during subsequent heat treatment or service processes. The HX-AM alloy exhibits an exceptional matching relationship between strength (ultimate tensile strength = 315 ± 3 MPa) and ductility (total elongation = 56 ± 1.7 %) at 900 °C. What's more, the creep performance of HX-AM alloy is significantly improved simultaneously compared with CM Ni-based alloys at 900 °C, overcoming the longstanding challenge of inferior creep performance in AM nickel-based superalloys at high temperature. The fatigue lifetime of HX-AM alloy reaches 295.6 h at 900 °C/40 MPa, showing over fifteenfold enhancement compared to that of CM Hastelloy X alloy.