Remnant grooves on alumina surfaces

Thermal grooving of grain boundaries in alumina has been studied using a combination of visible-light microscopy (VLM) and atomic-force microscopy (AFM). The partial angles of grooves that develop during heat treatments at 1650 °C were estimated by AFM. The observation of remnant grooves is key to determining the magnitude of the movement of a grain boundary. Imaging using VLM and AFM enabled the smoothing of remnant grooves to be observed through a progression of heat treatments, which enables the anisotropic nature of the surface diffusivity of alumina to be monitored.