2007 Volume 47 Issue 1 Pages 172-177
The in situ Ti5Si3 intermetallic particulate locally reinforced steel matrix composites are successfully fabricated by the self-propagating high-temperature synthesis (SHS) reaction of Fe–Ti–Si system during casting, and the microstructures of the composites reveal a relatively uniform distribution of mango-like Ti5Si3 particulates in the local reinforcing regions. XRD results reveal that in addition to α-Fe and Ti5Si3 phases, the transient Fe2Ti is also present in the local reinforcing region of the composites. Furthermore, some Ti3SiC2 particulates are formed and distribute in the limited region nearby the interface between the local reinforcing region and steel matrix. With Fe content increasing from 10 to 30 wt% in the preforms, the Ti5Si3 particulate size is decreased obviously in the local reinforcing region; furthermore, the presence of significant porosity can be detected in the composite synthesized by the 10 wt% Fe–Ti–Si system; on the contrary, only a minimal porosity can be found in that synthesized by 30 wt% Fe in Fe–Ti–Si system. The macro- and micro-hardness as well as the wear resistance of the local reinforcing region are obviously higher than those of the unreinforced medium steel. Improvements in hardness and wear resistance of the composite are mainly attributed to the presence of high volume fraction of hard intermetallic Ti5Si3 particulates.
