Development of the Fabrication Process for SiC Reinforced Gamma-TiAl Intermetallic Composites

The authors have focused on the TiAl-Cr alloy which displays superconductivity at relatively low temperatures and investigate the composite possibilities using foil shaped TiAl-Cr matrix with SiC fibers through use of conventional foil metallurgy technique. Upon reviewing the manufacturing conditions of composite materials, they present their evaluation results from mechanical tests. In conventional manufacturing method it has been normal to use alloys powder as the matrix to produce gamma -TiAl composite with SiC filaments. Among the application examples introduced here are a composite disc for which a photograph of finished product is provided. As the result of diffusion of oxides within TiAl sintered powder's base phase the room temperature ductility is compromised. The coefficient of tensile elongation in Ti-48at.%Al alloy powder at 1250 deg C shows a tensile fracture strain of 0.3%. A photograph shows the cross section of hot pressed (at 1250 deg C) SiC/powder TiAl composite. The addition of Cr to the matrix indeed shows an increased tensile strength at 800-1200 deg C as per graph which also reveals the relationship with the beta dominance region. Such Cr addition increases the volume ratio of beta phase to that of grain boundary.