Transient Liquid Phase Bonding Process in SiC Fiber Reinforced Ti-6Al-4V Composites.

Abstract

Continuous SiC fiber reinforced Ti-6Al-4V composites were joined to a Ti-6Al-4V plate by transient liquid phase (TLP) bonding process using Ti-Cu-Zr filler metal. Three processes, which were the dissolution of base metal, the isothermal solidification and the homogenization processes, were observed. The saturated dissolution width increased as the fiber volume fraction increased. Namely, the dissolution width was inversely proportional to the fiber volume fraction. Although the time for completion of the dissolution of bases metal and the isothermal solidification would be long with increasing fiber volume fraction, these two processes could be completed for a short time and so marked difference could not be observed. Homogenization process is important to obtain high strength joint. It was cleared that the process could approximate to one dimensional diffusion model.Since the filler metal was melted during the bonding process, the liquid phase reacted with the SiC fiber. As a result, the brittle products such as TiC, ZrC and Ti5Si3 were formed at the interface between the fibers and the filler metal. However, these products did not affect the joint strength because they were formed only at the end of fibers in very small amounts.