The powder size characteristics of tungsten carbide (WC) powders directly influence key properties (e.g. hardness, toughness) of hard metal based products (e.g. high-temperature- and wear-resistant tools). Tungsten carbide is prepared by reaction of tungsten and carbon. During this carburization process structural changes and grain coarsening appear. Moreover, WC grain size is directly influenced by the Grain Size Distribution (GSD) of the employed tungsten powder; which are commonly produced by hydrogen reduction of tungsten oxides (WOx). In the course of the process, water vapour is produced and reacts with the existing oxides forming volatile compounds. Volatiles are transported and deposited via Chemical Vapour Transport (CVT). This mechanism is believed to be responsible for the W grain growth, including abnormally large grains.The ultimate goal of this project is to elucidate and accurately capture into a numerical model the localised phenomena influencing, firstly, the tungsten grain nucleation and growth by CVT during the H2 reduction of WOx and, secondly, the further crystal structure evolution of WC during its synthesis from tungsten powders. For this purpose, the project will employ cutting edge technology, e.g. synchrotron phase-contrast, to investigate and quantify the underlying physics occurring in the course of such heterogeneous processes.The numerical representation of tungsten nucleation and grain growth as well as the WC synthesis will be implemented into a state-of-the-art multiscale and multiphysics platform in order to predict the thermo-chemical transformation processes occurring in the powder particles. Predictions for bulk formation will be completed by coupling the numerical platform to a phase-field software to provide microstructure information. This numerical representation is of pivotal interest for day-to-day carbides production research because the hostile environment is a barrier for direct measurements. Consequently, the assessment of different industrial set-points to help optimize the final tungsten carbide crystal structure will be enabled.