Regularities of heat release in tungsten siliconizing in a gasless combustion wave

An electrothermographic method was used to study the regularities of heat release and formation of the microstructure of tungsten disilicide with wide variation in the temperature regime of sample heating, including conditions modeling combustion-wave propagation in mixtures of tungsten and silicon powders. Emphasis is on the heat-release stage due to the crystallization of the disilicide phase from a supersaturated melt of WSi$_2$–Si. At this stage of the process, self-acceleration of the heat release is observed even when the sample temperature decreases. Growth of tungsten disilicide crystals occurs only at the heat-release stage. When the system is kept at the maximum temperature of the thermogram, further crystal growth is not observed over a period of time exceeding the duration of heat release by a factor of 10–20.