Thermal stability of an SCS-6/Ti-22Al-23Nb composite

Titanium aluminide matrix composites were subjected to isothermal exposure treatments in an inert atmosphere at temperatures up to 800 °C and for times up to 1000 h. Specimens were examined by transmission and scanning electron microscopy to investigate the effect of these treatments on the fiber-matrix interfacial reaction. The reaction layer increases a little in thickness with increasing exposure times and temperatures. The products of these reactions were identified and, at shorter times and lower temperatures, are primarily carbides and silicides based on TiC and Ti5Si3. After isothermal treatments at the longest times and highest temperatures, a new phase based on Ti3Si appears. The thermal stability characteristics of this composite appear to be superior to those of comparable systems.