Kirkendall porosity in joints of pure Ni/Ni-base superalloy CMSX-4 annealed at high temperature

Interdiffusion occurs when materials with different compositions are exposed to high temperatures for extended periods of time. In a diffusion couple of pure Ni and Ni-base superalloy CMSX-4 joined by diffusion welding, there's a flux of elements and vacancies. While CMSX-4's alloying elements diffuse into pure Ni, a reverse flux of Ni and vacancies occurs. This leads to Kirkendall-induced porosity near the joint interface, potentially causing joint failure. The porosity evolution depends on material composition, crystallography, temperature, and stress duration. The study aims to investigate similar conditions as a previous study (ME 1513) but with a Ni/CMSX-4 joint with different crystallographic orientations and annealing times. Combining the experimental µ-tomography data with the phase-field and continuum simulations should provide information into the complicated mechanisms of void formation, evolution and kinetics of the kirkendall-porosity.