Abstract: For superalloys containing a high-volume fraction of precipitates, such as GH4065A alloy, the preferred inertia friction welding (IFW) process inevitably leads to the localized mechanical degradation in the weld zone (WZ) due to the reprecipitation of nanoscale tertiary γ' precipitates (γ'_III) phases, significantly restricting their practical application. In this regard, this study innovatively applied the electric current treatment (ECT) on the heterogeneous IFW joints, achieving targeted microstructural regulation within the WZ and enhancing the creep resistance performance of IFW joints. Results demonstrated that ECT efficiently and precisely regulated γ'_III growth in the WZ, achieving a 243.1 % size increase at 800 °C/0.5 h (compared to 43.4 % with conventional aging treatment at 800 °C/5 h), while also avoiding γ'_II over-coarsening in the base metal. Growth kinetics analysis indicated that ECT lowered the growth activation energy for γ' precipitate by ∼25 % (from 259.89 to 196.53 kJ/mol). Consequently, the creep rupture life of GH4065A IFW joints was extended from 10.8 to 102.9 h (650 °C/970 MPa) due to the optimal γ'_Ⅲ size control (below ∼54 nm), which preserved weakly coupled dislocation shearing as the dominant deformation mechanism. Moreover, finite element modeling calculations attributed this targeted regulation to the synergistic and amplified Joule heating and electron wind effects in the WZ, which promoted the precipitate elemental diffusion. Therefore, ECT provides a promising technical approach to efficiently achieve the targeted regulation of heterogeneous friction welds.

Key words: Highly-alloyed Ni-based superalloys, Heterogeneous friction welded joint, Targeted regulation, γ' strengthening phase;, Creep resistance improvement