Radiation-enhanced high-temperature cobalt diffusion at grain boundaries of nanostructured hardmetal

In situ annealing a FIB lamella obtained from nanostructured WC-Co hardmetal in a transmission electron microscope at 950 °C leads to the dissolution of some Co interlayers and small Co pools. The surface of the WC grains adjacent to the dissolved Co pools contains significant amounts of cobalt diffused to the surface of these WC grains from the Co pools. The observed new phenomenon of the abnormally fast Co diffusion at WC/Co grain boundaries is presumably caused by the combined effect of the high temperature and electron irradiation by an electron beam in the transmission electron microscope.