Microstructure and strengthening mechanism of diffusion bonding joints of 6063 aluminum alloy under the monomolecular surface protection of α-terpineol

6063 aluminum alloy is often used in the manufacture of microchannel heat exchangers, which are formed by diffusion bonding to connect laminates, and diffusion bonding is a key technology that determines the production quality. However, the Al₂O₃ oxide film with a stable surface and high melting point obstructs the close contact and atomic diffusion of the surface to be bonded, causing problems in diffusion bonding. In order to solve this problem, we propose a novel eco-friendly strategy using α-terpineol for monomolecular surface protection. Its terminal hydroxyl groups form a self-assembled film, suppressing secondary oxidation and fracturing the stable Al₂O₃ layer. The temperature of the diffusion bonding process is 570 °C, the pressure is 4 M Pa, and the time is 30∼120 min. The enrichment of Mg and Si enriched Mg₂Si and O elements was observed at the joint interface. When the bonding temperature was 570 °C and the bonding time was 90 min, the joint tensile strength reached 128.3 M Pa and the elongation was 28.8 %. This work establishes α-terpineol as a sustainable, and provides theoretical basis and technical support for the diffusion bonding process of AA6063 aluminum alloy.