Experimental and theoretical study of diffusion bonding in fabricating Ti matrix composite

Ti6Al4V/TA1 diffusion couples were fabricated and then heat-treated in vacuum under different conditions. The metallographic structure, morphologies and the composition distribution in diffusion bonding zone were investigated by means of OPM, SEM and EDS. The results indicate that the diffusion couples are bonded well; the alloying elements Al and V diffuse from Ti6Al4V to TA1, and Ti atoms diffuse in the opposite direction. The transition zone of the alloying elements obeys a rule of parabolic rate. At the same time, based on Koher's ternary solution model and Miedema's model for calculating the thermodynamical interaction coefficients, the theoretical diffusion profiles of Ti and alloying elements are obtained according to the inter-diffusion coefficients of the alloying elements and the numerical solution of the phenomenological equation. Moreover, the calculated values are well fitted to the experimental data. So the distribution of the diffusion atoms can be predicted at the diffusion bonding interface.