Microstructure and mechanical properties of spark plasma diffusion-bonded 5A06Al joints with Al–20Cu–5Si–2Ni interlayer

Spark plasma diffusion welding (SPDW) is a powerful technique for joining materials at a remarkably short time with excellent quality. In this paper, SPDW of 5A06Al alloy to itself was conducted with Al–20Cu–5Si–2Ni brazing filler alloy added as the interlayer. In the bonding temperature ranging from 520 to 550°C, pressure from 0.3 to 6 MPa, and holding time from 10 to 20 min, the optimal joint was obtained at bonding temperature of 540°C and pressure of 6 MPa for 10 min. Results showed that the void-free 5A06Al/5A06Al-bonded joint was obtained at the optimized parameters with the aiding of electric current and Al–20Cu–5Si–2Ni interlayer. Increasing the bonding pressure produced more refined grains in the bonding joint and was therefore beneficial to the bonding quality. The formation of refined eutectic phases, the accelerated atomic diffusion, the sufficiently removal of oxide film, and the evidently more narrowed bonding interface areas were helpful to strengthen the SPDW joint. The most efficient bonding joint had a tensile strength of as high as 220 MPa and exhibited typical fine ductile dimple fractography. Comparatively, the poorest joint quality was obtained at lower bonding temperature and pressure, i.e., bonding temperature of 530°C, pressure of 0.3 MPa, and holding time of 10 min.