Development of SiC/TiAl composites: processing and interfacial phenomena

The needs of the aerospace industry for materials with low density and suitable mechanical properties at elevated temperature have oriented research to TiAl/SiC intermetallic matrix composites. A fabrication method specific for such composites was developed in this study. Two types of long fibers that have been used are the BP SM 1240 and Textron SCS-6 silicon carbide monofilaments. To fabricate these composites, firstly, the arc spraying conditions have been optimized by preparing sprayed Ti–48Al–2V material on a steel substrate and both types of Ti–48Al–2V/SCS-6 and Ti–48Al–2V/SM 1240 monotapes. Secondly, we have investigated the conditions under which a Ti–48Al–2V alloy powder could be consolidated and the kinetics of fiber damage by chemical reaction with the TiAl base matrix observed during consolidation. Then composite samples have been fabricated by uniaxial hot pressing of monotapes. In both composites, an interaction occurs between the fiber and the matrix and the reaction zone thickness follows approximately a parabolic growth law. It was determined that the plasma spray process is well adapted to produce titanium aluminide matrix composites. However, efforts are in progress to solve some of the problems inherent in the choice of the fiber, matrix and interfacial characteristics.