Titanium carbide based composites for high temperature applications

Titanium carbide based composites with nickel alloys and iron alloys ave currently used in high performance applications where wear and corrosion are the main sources of material failure. For high temperature critical applications, however, the metallic binders nickel and iron limit the use of TiC-based composites. Hence, new binder systems which have good high temperature properties need to be developed in order to extend the use of TiC-based composites. Silicides and aluminides are potential binder systems with their good high temperature corrosion and mechanical properties. In this study, two binder systems, Fe-25 at% Si and Fe-40 at% Al have been selected, and were processed with reaction sintering of elemental lie and Si, or Fe and Al powders, with 65 wt% TiC and 80 wt% TiC powders at temperatures at around 1410-1430 degrees C under vacuum. X-ray diffraction analysis show TiC and Fe3Si phases in the TiC-iron silicide composites, whereas TiC, Fe3Al2 and Fe3AlC0.5 phases were observed in TiC-iron aluminide composites. Differential thermal analysis of the samples shows that liquidus temperatures of the iron-silicide and iron-aluminide binders weve around 1265 and 1425 degrees C, respectively. Vickers microhardness values of 1100-1470 kg mm(-2) and 3-point bending strengths of 600-775 MPa were obtained in these high density reaction sintered TiC-iron silicide and TiC-iron aluminide composites. (C) 1999 Elsevier Science Ltd. All rights reserved.