Tailoring precipitation through magnetic field-assisted heat treatment for strength-ductility synergy in IN718 superalloy

The high-temperature strength of IN718 superalloy mainly depends on precipitates. However, conventional thermal aging often causes precipitate coarsening, which limits the simultaneous improvement of strength and ductility. In this study, magnetic field-assisted heat treatment is employed to regulate precipitation kinetics and microstructural evolution in IN718 superalloy. The application of a strong magnetic field during aging increases the precipitate volume fraction by reducing the effective kinetic barrier for nucleation. Consequently, nucleation is preferentially promoted over precipitate growth, leading to a microstructure with a high density of fine precipitates. In addition, magnetically enhanced elemental diffusion promotes a more homogeneous precipitate distribution within the matrix and accelerates the precipitation process. The resulting homogeneous precipitates enhance precipitation strengthening while preserving a high work-hardening rate during deformation. As a result, the magnetic field-assisted heat treatment achieves higher strength together with improved elongation, offering an effective pathway to overcome the strength-ductility trade-off in IN718 superalloy.