Methods for atom probe study of near surface zones in cemented carbides

Methods to prepare atom probe specimens from near-surface regions of cemented carbide cutting tool inserts have been developed. The preparation technique involves dimple grinding and electropolishing. The specimens are prepared parallel to the surface to allow pulse electropolishing without changing the depth from the surface. The material studied is a gradient sintered WC–Ti(C,N)–Co based cutting tool insert with a gradient thickness of 35 μm. We have so far been able to produce a tip within 5±2 μm from the zone border. Furthermore, the method makes it possible to prepare tips from as close as 10 μm from the surface. An atom probe analysis of a region near the zone border is presented.