Unraveling nano-scale interfacial structure and strengthening mechanism of Al-TiB2/Mg laminate through quasi-in-situ observation

Controlling the interfacial evolution mechanisms in Al-TiB 2 /Mg laminated composites is critical for optimizing their mechanical performances. This study employed multiscale characterizations integrating quasi-in-situ analysis, to systematically investigate the grain structure, elemental diffusion, interface nanostructure and interface mechanical properties. The results indicate that the interfacial solid solutions are transformed into β and γ intermetallic compounds (IMCs) layers during annealing process, and IMCs thickness exhibits temperature- and time-dependent growth kinetics. The introduction of TiB 2 particles in the Al layer effectively suppress the growth of β layer. High-temperature annealing triggers abnormal grain growth concurrent with Al 12 Mg 17 dissolution in Al layer. The stacking faults (SFs), Lomer-Cottrell (L-C) locks, and twin boundaries are identified in β layer after annealing at 250 °C for 2 h, and they collectively exert impeding effects on dislocation motion. These obstruction effects and defect density substantially diminishes after annealing at 400 °C for 1 h. Al/β interface is transformed from an ordered-disordered 3D transition region to an ordered transition zone by low-temperature annealing, evolving from an incoherent interface to a semi-coherent interface. Conversely, high-temperature annealed Al/β interfaces displays incoherent characteristics with disordered mixing zone. The bonding strength exhibits a marked sensitivity to the IMCs thickness. After annealing at 250 °C for 2 h, the Al-TiB 2 /Mg laminate exhibits an optimal balance with the bonding strength of 35.0 MPa and IMCs thickness of 4 µm. These findings establish fundamental insights for regulating the interfacial structure and lattice mismatch in Al-TiB 2 /Mg laminated composites.