Investigation of a novel laser powder bed fusion nickel-based superalloy with hf, Y addition: Melt characteristic, microstructure and mechanical properties

Abstract

In order to resolve the inherent strength-ductility trade-off dilemma observed in precipitation-strengthened nickel-based superalloys with high Al and Ti content, a composition modification strategy was devised. This study explored a novel laser powder bed fusion (LPBF) René104 alloy by incorporating Hf and Y (HfY-René104), examining its melt characteristics, microstructures, and mechanical properties. The experimental results demonstrate that the addition of Hf and Y effectively improves the molten pool structure of the as-built, alters grain orientation, diminishes grain aspect ratio, promotes the formation of cellular structures, AlY phases, stacking faults (SFs), and Lomer-Cottrell (L-C) locks at macro, meso, and micro scales, respectively. The primary contributors to yield strength are grain boundary strengthening and dislocation strengthening. Moreover, a dynamic Hall-Petch effect associated with cellular structures, SFs, and L-C locks ultimately results in remarkable strength (yield strength of 823 MPa, ultimate tensile strength of 1158 MPa) and enhanced ductility (elongation of 24.6 %) of HfY-René104 alloy.