Hardmaterial – from microstructure to applications.

2023-11-16 Lecture by prof. Susanne Norgren. Abstract: Hardmetals, or Cemented carbides, are a composite material consisting of hard tungsten carbide grains embedded in a metal matrix usually cobalt. The grain size of the tungsten carbide grains vary from 200nm in submicron cemented carbides to 15 micron in very coarse grain cemented carbides. The grain size is carefully controlled during manufacturing and the selection of final grain size is determined by the needs of the application. In this system the grains are facetted and to understand the mechanisms of grain growth and how to control it during sintering is of vital importance. In this presentation controlling and modelling of grain growth will be discussed, as well as still open questions. Another important parameter in the microstructure, are the phase-interphases and the tungsten carbide/tungsten carbide grain boundaries. Studies of grain and phase boundaries, using atom probe tomography and creation of interfacial phase diagrams to understand grain growth and grain boundary chemistry and in the end impact on material properties will be discussed.