Effect of a NiO Additive on Interaction in a Ni–Al–W System in Self-Propagating High-Temperature Synthesis

Resumo

An effect of a NiO additive on the combustion and structure formation in a Ni–Al–W system in self-propagating high-temperature synthesis (SHS) is under study. The stages of the combustion of compositions containing a NiO high-energy additive are shown. The interaction of W particles with Ni–Al melts during SHS results in the formation of globular decoration of particles on the basis of solid solutions of tungsten on the particle surface. This effect is observed only in compositions with an equimolar mixture of Ni–Al. With an NiO additive content in the initial sample more than 1 at.%, the globular decoration on the unreacted W particle surface does not occur. This effect can be associated with changes in the combustion temperature, deviation of the NiAl phase in the direction of a larger content of Ni, and the influence of oxide phases on diffusion processes.