Grain boundary grooving at the singular surfaces

Abstract The unusual topographies of the grain boundary thermal grooves in Ni-rich NiAl were observed after annealing at 1400°C. One of the surfaces forming the grain boundary groove exhibited no curvature measurable in the atomic force microscope, thus indicating its singular character. The theory of grain boundary grooving at singular surfaces was developed in the small-slope approximation and under assumption of negligible diffusivity on these surfaces. The calculated groove shapes are in good agreement with the experimental data and differ considerably from the shapes predicted by the classical Mullins grooving theory for isotropic surfaces.