Synthesis of Cr-Si intermetallic compounds by field-activated combustion synthesis

The use of an electric field to activate the combustion synthesis of chromium silicides was investigated. Despite their relatively low adiabatic temperatures, all fi,ur silicides were synthesized by field-activated combustion synthesis. However, although self-propagating synthesis reactions were initiated, the products were not pure but contained other silicides and reactant phases. The purity of the samples increased with increasing field strength, and under the highest field, the products contained the desired silicide as the major phase with minor amounts of other stoichiometries. Observation of microstructural evolution in quenched reactions revealed the key role played by the liquid phases in the propagation of the combustion front, The phase Cr5Si3 was the first product of the interaction between the reactants when either solid-solid or solid-liquid processes were involved. These results were confirmed by isothermal solid-solid and solid-liquid diffusion couple experiments.