Superalloy components are joined by mating a recess formed in one component with a corresponding projection formed in another component along a contact surface. The components are compressed along the contact surface and resistance heat welded to each other. Current is passed between the components at a selected flow rate and application time until localized melting occurs along the contact surface, and they are mutually affixed to each other. When repairing a damaged surface portion of a superalloy material component, the damaged portion is removed to form an excavated recess. A repair splice is formed, preferably of a same material with similar mechanical structural properties, having a mating projection with profile conforming to the corresponding recess profile. The splice and substrate are resistance heat welded under compression pressure until localized melting occurs along the contact surface, so that they are mutually affixed.