Time-resolved diffraction studies of fast solid combustion reactions at high temperature

Abstract

Real time synchrotron diffraction has been used to monitor the phase transformatins of highly exothermic, fast self‐propagating solid combustion reactions on a subsecond time scale down to 50 milliseconds. A specially designed reaction chamber was constructed to enable simultaneous in situ diffraction and IR thermal imaging to be measured. A position‐sensitive photodiode array detector capable of a full scan of 1024 pixels in 4 ms was used to record the time‐resolved diffraction patterns from a fixed location of the specimen during passage of the combustion wave front. The detector was triggered by an inframetric camera or a thermocouple placed upstream from the area illuminated by the x‐rays. The phase transformations and chemical changes in a number of simple binary systems of the type A+B→AB are reported here. These include Ti+C→TiC, Ni+Al→NiAl, Ta+C→TaC, and 2Ta+C→Ta2C. This new experimental approach can be used to study the chemical dynamics of high‐temperature solid‐state phenomena and to provide the needed database to test various models for solid combustion process.