Effects of Joining Conditions on Microstructure and Mechanical Properties of Cf/Al Composites and TiAl Alloy Combustion Synthesis Joints

Abstract

Cf/Al composites and TiAl alloy were joined by combustion synthesis in different joining conditions. Effects of additive Cu, joining temperature and holding time on joint microstructure and shear strength were characterized by employing DTA, SEM, EDS, XRD and shear test. Results show that the additive Cu in the Ti–Al–C interlayer could significantly decrease the reaction temperature owing to the emergence of Al–Cu eutectic liquid. Reaction degree of the interlayer was influenced by joining temperature and holding time. Due to the barrier action of formed TiAl3 layer, reaction rate of Ti and Al was determined by the atoms diffusion. The reaction between Ti and Al was more sensitive to the joining temperature rather the holding time. The joints shear strength was influenced by joining condition directly. The maximum shear strength of CS joints was 25.89 MPa at 600 °C for 30 min under 5 MPa. Interface evolution mechanism of the CS joint was analyzed based on the experimental results and phase diagram.