Investigation of high-strength and high-precision pulse-current-assisted diffusion bonding of Ti-6Al-4V alloy

In this study, a new strategy for the fabrication of high-strength and high-precision diffusion bonding joints is proposed by combining high-pressure pulsed-current-assisted diffusion bonding (PCADB) at a low temperature for a short time and post-bonding heat treatment (PBHT). High-quality bonding joints were obtained by this technique. When the bonding temperature was 550 degrees C and 600 degrees C, the tensile strength reached 768.2 MPa and 862.1 MPa respectively after PBHT, which was equal to 84.0 % and 94.6 % of that of the base material. Meanwhile, the deformation rate at the bonding temperatures of 550 degrees C and 600 degrees C was controlled at 1.08 % and 1.12 %, respectively. The microstructure characterization of needle-like grains and sub-grains demonstrates the role of the high pressure and the in-situ heating induced by pulsed current. Furthermore, the numerical calculations were performed and the relevant microstructure evolution models were established.