Effects of hot isostatic pressing treatment on the microstructure and tensile properties of a novel high‐γ′ Ni‐based superalloy manufactured by laser directed energy deposition

Abstract A novel high‐γ′ Ni‐based superalloy designed for additive manufacturing (AM) was processed via laser directed energy deposition (L‐DED) to investigate hot isostatic pressing (HIP)‐induced microstructural evolution and mechanical enhancement. The as‐built condition exhibited cellular dislocation networks with 0.062% residual porosity, achieving an exceptional yield strength (YS) of 1005 MPa and elongation of 20.2%. Post‐HIP treatments at 1150 and 1190 °C effectively eliminated porosity (defect density reduced to ~ 0.02%), homogenized the microstructure, and promoted γ′‐phase precipitation (342 nm at 1150 °C and 320 nm at 1190 °C) and recrystallization. These microstructural modifications enable retention of excellent strengths (UTS: 1462–1491 MPa, YS: 932–944 MPa) while enhancing ductility by 33%–40% (26.9%–28.3% elongation), outperforming conventional AM counterparts. The 1190°C HIP condition particularly demonstrated superior crack resistance through γ′ refinement and increased high‐angle grain boundary (HAGB) density. Based on multi‐scale characterization, quantitative models were developed for yield strength predictions, revealing a transition from dislocation‐dominated hardening (as‐built) to γ′‐precipitation hardening (HIP‐treated). This work establishes HIP as an essential post‐processing protocol to circumvent the intrinsic strength–ductility conflict in additively manufactured superalloys for advanced aerospace applications.