High-temperature synthesis in activated powder mixtures under conditions of linear heating: Ni–Al system

In the present paper, a mathematical modeling of high-temperature synthesis process in powder system Ni + Al under linear heating conditions was carried out. A comparative analysis of numerical modeling results and experimental data which were obtained for mechanically activated powder mixtures is pre- sented. The criterion for determining the characteristic ignition temperature in the case of forced ignition was proposed. This criterion makes it possible to establish a relationship between the thermokinetic pa- rameters at the ignition limit. With the use of the model, the dependencies of the ignition temperature, the induction time, and the conversion degree on the effective activation energy were established. It was found that these dependencies are close to linear that allows making the predictive estimates. It was shown that the ignition temperature depends most significantly on the activation energy of the synthesis while its dependence on other kinetic parameters is of secondary importance. Based on the criterion pro- posed, an alternative method for determining the effective activation energy of synthesis was considered