In Situ Laser Irradiation of WC--Co Hard Metals Inside a Scanning Electron Microscope. II. Behaviour of the Cobalt Binder

Cemented carbides with higher binder contents (WC--20 wt.% Co) were irradiated with a CO sub 2 -pulse laser within a SEM to investigate the structural development in more detail. The decisive medium is the melting binder which dissolves the refractory carbide phase. In this way, a superficial layer of an oversaturated solids solution with highly dispersed secondary carbides is produced. At higher pulse numbers, a periodic structure is engraved in the surface by local evaporation as a result of a self-amplifying resonance phenomenon. Graphs, Photomicrographs, Phase diagrams. 16 ref.--AA