Abstract: Additive manufacturing of GH3536 nickel-based superalloys offers significant potential for producing geometrically complex or customized aero-engine components. However, the inherent strength-ductility trade-off, leading to low ductility and inferior elevated temperature mechanical properties, has posed substantial challenges for additively-manufactured GH3536 superalloys, thereby restricting their potential applications in the aero-engine components. To this end, we proposed precisely engineered dual-heterostructures via conventional solution treatment to enhance the mechanical properties of GH3536 superalloys fabricated via laser powder bed fusion (LPBF) technology at both room and elevated temperatures. By meticulously controlling the solution treatment temperature, a well-designed dual-heterostructure has been introduced into LPBFed GH3536 alloys. Such customized dual-heterostructures are not only distinguished by the alternating arrangement of coarse grains (CGs) and fine grains (FGs) regions but also by the homogeneous dispersion of nanoscale carbides and high-density tangled dislocations within the FGs regions, as well as the presence of annealing twins within the CGs regions. The tailored dual-heterostructures facilitate heterogeneous deformation-induced strain hardening, leading to an outstanding strength-ductility synergy in LPBFed GH3536 alloys at various temperatures. Compared to the acid pickling (AP) specimen, the tensile strength and ductility of the designed alloys are significantly enhanced by approximately 2 % (825 MPa) and 163 % (71.6 %) at room temperature, respectively, and by about 27 % (772 MPa) and 225 % (35.1 %) at 650 °C. According to theoretical calculations based on strengthening models, it is evident that dislocation and solid-solution strengthening primarily govern the yield strength of the AP specimen, while solid-solution strengthening predominates in the ST1160 specimen. This study offers an insightful paradigm for designing alloys with exceptional strength-ductility synergy via introducing dual-heterostructures.

Key words: Additive manufacturing, Nickel-based superalloys, Solid solution treatment, Dual-heterostructures, Mechanical properties, Strength-ductility synergy