Fibre/matrix reactions in plasma sprayed composite monotapes (SiC-Ti6Al4V) at high temperatures

Titanium-based alloys have found increased use in high temperature applications due to their excellent strength-to-weight ratio. In many cases, noticeable increases in specific strength and stiffness can be achieved through continuous fibre reinforcements. Of primary interest in many applications are the SiC-Ti6Al4V composites. One of the major problems faced with this composite system is the degradation of composite properties by the reaction of the titanium matrix with silicon carbide fibres at high temperature. Interfacial reactions can be due to fabrication methods and to the long term use at high temperatures. Typical fabrication conditions result in the formation of a reaction zone consisting of TiC near the fibre surface, and various amounts of brittle titanium silicides, including Ti5Si3, TiSi or TiSi2 [1– 8]. To reduce the thickness of the reaction zone it is possible to fabricate monotapes by inert plasma spraying [9], because this technology reduces liquid metal=ceramic fibre contact time (about 100 ms) due to the high solidification rate of sprayed metal droplets