High-performance direct diffusion-bonded SiCp/Al composites joints via pulsed current: Strategy and mechanism for overcoming interfacial barriers

: Precision-bonding of the SiCp/Al structure plays a decisive role in HPIM production. However, the oxide film and ∼5-fold melting temperature difference of SiC and Al matrix hinder the bonding process at a temperature below the melting point of Al alloy. This study aimed to overcome the above challenges, realize high-strength precision bonding of SiCp/Al under fully solid-state conditions, and thus support the iterative upgrading of HPIM. Herein, a practical strategy was proposed for the precision fabrication of SiCp/Al integrated structure: Pulsed current assisted diffusion bonding (PCDB) without filler materials. Elemental diffusion and deoxygenation reaction were synergistically stimulated at the interface domain by the interface-concentrated Joule heating. Therefore, a directly tight bond of Al/SiC sub-interface was formed at such a low temperature below the melting point of Al alloy. Simultaneously, the electroplastic effect enhanced dislocation motion within the Al matrix, thereby reducing the deformation resistance. Rapid closure of the bonding interface was thus achieved. Ultimately, PCDB yielded a direct bonding joint with a shear strength of 85.04 MPa and a deformation rate of merely 0.62% at 500 °C / 60 min / 10 MPa. Finally, the high-strength and micro-deformation bonding of SiCp/Al has been achieved, as a breakthrough that advances HPIM fabrication technology.