Escape of carbon element in surface ablation of cobalt cemented tungsten carbide with pulsed UV laser

Surface ablation of cobalt cemented tungsten carbide hardmetal has been carried out in this work using a 308 nm, 30 ns XeCl excimer laser. The surface phase transformation on different pulse number of laser shots has been investigated by means of XRD and microphotography as well as AES at laser ¯uence of 2.5 J/cm2. The experimental results showed that the phase structure of irradiated area has partly transformed from original WC to b-WC1ÿx, then to a-W2C and CW3, and ®nally to W crystal. It is suggested that the formation of non-stoichiometric tungsten carbide should result from the escaping of carbon element due to accumulated heating of surface by pulsed laser irradiation. # 2001 Elsevier Science B.V. All rights reserved.