Non-destructive analysis of the tungsten carbide grain size by means of two-dimensional X-ray diffraction

The mechanical properties of cemented carbides like hardness, strength and ductility are strongly affected by the tungsten carbide grain size. In order to achieve microstructural characteristics suitable for a particular application, continuous monitoring of the grain size during the complete manufacturing process is essential. However, currently available test methods give only rough estimates of the grain size or require impractically long sample preparation and measurement times. Two-dimensional X-ray diffraction offers new possibilities for fast non-destructive grain size analysis under laboratory conditions. This work investigates the applicability of the X-ray diffraction method to quantify the tungsten carbide grain size in a polycrystalline material. In a first step, highly pure tungsten carbide powder samples with various degrees of agglomeration are used to demonstrate the potential of two-dimensional X-ray diffraction for grain size determination. In a second step, the applied approach is tested for a set of cemented carbides with a mean cobalt weight content of 10% and grain sizes varying from the ultrafine to the extra coarse range. Though the obtained results refer solely to tungsten carbide, the methodical concept of grain size analysis by means of two-dimensional X-ray diffraction is generally practicable for polycrystalline materials.