Dual-solution-precipitation mechanism of combustion synthesis of TiC-Fe cermet with fine Ti powder

A Ti-C-Fe powder mixture with a finer Ti powder was used for a combustion f ront quenching test to investigate the effect of titanium particle size on the mechanism of the combustion reaction, and the microstructural evolution in the quenched specimen was then observed with scanning electron microsco py, and the combustion temperature was also measured. The results showed th at the nature of the combustion reaction could be described with a dual-sol ution-precipitation mechanism and a correspondent model. The melting of the finer Ti particle prior to its reaction was attributed to a combined effec t of two factors: a decrease of its size-controlled melting point, and a de crease of its composition-controlled melting point. The use of the finer Ti powder led to a more complete combustion reaction and hence a higher combu stion temperature. As a result, the combustion-synthesized TiC-Fe cermet ha d a greater average size of TiC particles and layer-shaped pores that was c onfirmed to be a consequence of gathering of the evolved gases into the com bustion wavefront. (C) 2001 Kluwer Academic Publishers.