<p>Diffusion depths and diffusion paths were systematically analyzed in iso-concentration couples in <i>β</i>-(Ni,Pt)Al system. The iso-Al couples exhibited the lowest effective penetration depths of all studied diffusion couples, highlighting minimal interdiffusion. In iso-Pt diffusion couples, the one containing about 10-at. pct Pt showed the lowest diffusion depths for the same differences of Al concentrations in terminal alloys. Based on the defect energetics reported in the literature and their consistency with the observed diffusion depths and interdiffusion coefficients in the present study, Al triple defect appears to be the dominant mechanism for diffusion of Al, which also contributes to the diffusion of Ni in opposite direction. Ni diffusion, in turn, seems to be influenced by both the Al triple defect and the ASB mechanism. The linearity observed in diffusion paths of the iso-Pt and iso-Al diffusion couples was correlated to effective interdiffusion coefficients revealing a key finding that a linear diffusion path does not always imply absence of diffusional interactions among elements. Furthermore, utilizing effective interdiffusion coefficients, solute diffusivity of Pt in binary Ni–Al alloy was determined and it was found to decrease with increase in Al concentration. These observations are crucial in designing bond coat systems to effectively control interdiffusion and related microstructural degradation during service.</p> Graphical Abstract <p></p>