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

The use of an electric field to activate the combustion synthesis of chromi um silicides was investigated. Despite their relatively low adiabatic tempe ratures, all fi,ur silicides were synthesized by field-activated combustion synthesis. However, although self-propagating synthesis reactions were ini tiated, the products were not pure but contained other silicides and reacta nt phases. The purity of the samples increased with increasing field streng th, and under the highest field, the products contained the desired silicid e as the major phase with minor amounts of other stoichiometries. Observati on of microstructural evolution in quenched reactions revealed the key role played by the liquid phases in the propagation of the combustion front, Th e phase Cr5Si3 was the first product of the interaction between the reactan ts when either solid-solid or solid-liquid processes were involved. These r esults were confirmed by isothermal solid-solid and solid-liquid diffusion couple experiments.