Laser cladding of IN625 on Rene125 superalloy: Effect of tailored post- heat treatments on interfacial properties

This study systematically investigates the laser deposition of IN625 alloy onto the cast superalloy Rene125, with a focus on optimizing a tailored multi-stage heat treatment cycle to control microstructure, eliminate brittle phases, and mitigate residual stresses at the Interface. Post-deposition, samples underwent a heat treatment protocol comprising solutionizing at 1220 °C for 2 h, air-cooling to 590 °C, and subsequent controlled furnace cooling. This targeted thermal cycle fully suppressed Nb and Mo segregation within the IN625 cladding, transforming the initial dendritic microstructure into a homogeneous structure. At 1220 °C, metastable M₂₃C₆/M₆C carbides dissolved, while stable MC carbides (1–3 μm) precipitated at grain boundaries during furnace cooling. Residual stresses at the Interface were reduced from 253 MPa to 4 MPa (98 % reduction), demonstrating the efficacy of the proposed approach. The findings underscore that appropriately designed post-deposition heat-treatment cycles can yield substantial improvements in metallurgical bond quality and potentially extend fatigue life by up to 3.96 times in superalloy systems, thereby providing a strategic pathway for optimizing additive manufacturing processes in high-temperature applications.