Microstructure Control of Ceramic-Intermetallic Composites by Heat-Treatment before Combustion Synthesis

Abstract

When mixtures of Fe, Al, Ti and B powders were heated, the combustion synthesis, or SHS, reaction occurred and produced a TiB2 particle dispersed FeAl-based composite. The TiB2 particle size increased with increasing TiB2 volume fraction from 0.3 to 0.8, which was considered to be due to the fact that the adiabatic temperature of the reaction increases with the increase in TiB2 concentration in the composite due to the large formation enthalpy of TiB2. The TiB2 particle size decreased with increasing preheating time, temperature and pressure before the SHS reaction. It was suggested that partial reaction between elemental powders before the SHS reaction reduced the adiabatic temperature and hence the TiB2 particle size. The Vickers hardness of the composite varied from 500 to 2000 depending on the microstructure. This method was applied to the production of TiC-FeAl, TiC-Fe, TiB2-Fe composites.