Achieving exceptional strength by multi-dimensional in-situ Al3Ti, TiN, AlN reinforcements in Al matrix composites

Abstract

Despite the high demand for strong, lightweight, and tough Aluminum Matrix Composites (AMCs) across various applications, achieving desired property compatibility remains challenging due to limited control over the reinforcement processes. A novel AMC has been developed and synergistically reinforced with transgranular microscale Al3Ti, sub-microscale TiN, and intergranular nanoscale AlN, through Ti2AlN and Al in situ reaction. The in-situ multiphase-and-scale structure, resulting from the intricate reaction mechanisms and N interstitial solution, was analyzed using experimental investigations, thermodynamics and kinetics calculations, while the robust interfacial properties were studied by first-principles calculations. Both endowed the composite with exceptional strength (776 MPa and 635 MPa for compressive and flexural strength). Strengthen mechanisms were composed of fine-grain, solid-solution, and dislocation strengthening. This work succeeds in refining Al3Ti particles and creatively breaks through the bottleneck of synthesizing multi-dimensional and tunable in-situ reinforcements, expected to open new avenues for developing and applying a new generation of advanced AMCs.