Influence of O and Co on the early stages of sintering of Wc-Co:: A surface study by AES and STM

The influence of oxygen on the sintering behavior of WC-Co has been investigated by Auger electron spectroscopy (AES) and scanning tunneling microscopy (STM). Deposition of Co on the WC(0001) surface and subsequent annealing at 650 degreesC results in a 2x2 reconstructed pre-cursor layer on top of which Co grows in weakly bound islands which can be moved on the surface by the STM rip. Annealing at 850 degreesC removes excess Co and leaves only the 2x2 surface. Oxygen exposure of the 2x2 surface results in a "clustered" cobalt oxide overlayer which on annealing at 750 degreesC breaks up and restores the 2x2 structure as the metallic Co wets the surface. (C) 2000 Acta Metallurgica. Published by Elsevier Science Ltd. All rights reserved.