Densification of potassium-doped tungsten during sintering

•Usage of thermo-optical device for in-situ measurement of shrinkage during sintering.•Experimental data allow calibration of master sintering curve model parameters.•Resulting model predicts density evolution regardless of heating regime.

Tungsten is traditionally sintered at very high temperatures. The master sintering curve (MSC) for densification is a functional model that describes sintering under an arbitrary time–temperature regime of a particular material during heating. The MSC for potassium-doped tungsten (W-K) has been determined by fitting experimental relative density data results versus work of sintering data with a modified sigmoid function. Five independent parameters of the fitting function are identified by minimizing error in terms of mean residual square. For measurement of relative density during sintering, we developed a non-contact high temperature dilatometer experiment using an optical method. Densification was continuously recorded at constant heating rates of 5, 10, 20, 30 and 40 °C/min. The work presented here was carried out to predict and control densification evolution of W-K during free sintering. The results demonstrate, that the MSC model of W-K describes densification independently of selected temperature regime.