Al3BC/6061 Al composite with an exceptional combination of strength and plasticity fabricated via melt casting

Al 3 BC, as a promising reinforcement for Al composites, has attracted extensive attention in recent years. However, there are no reports on the preparation of Al 3 BC/Al composites by the casting method. This study proposes a new method of introducing Al-B-C composite precursors into the Al melt to overcome the poor wettability and low solubility of boron and carbon precursors. Combined with mechanical stirring and ultrasonic treatment, this method achieves the in-situ synthesis and dispersion of Al 3 BC in the Al melt. Through this method, Al 3 BC/6061Al composites with 1 wt.% Al 3 BC have been successfully prepared. The in-situ synthesized nano and sub-micron Al 3 BC particles are distributed in the form of small clusters along the grain boundaries. After the rolling deformation and further T6 heat treatment, the composite shows an exceptional combination of strength and plasticity, with a tensile strength of 341.3 MPa and elongation of 14.9%. Compared with the 6061 Al alloy, the introduction of Al 3 BC not only increases the strength but also maintains or even improves the elongation of the matrix alloy, confirming its excellent strengthening and plasticity effect. Microstructure studies show that the excellent strength of the Al 3 BC/6061Al composites is attributed to the fine grain strengthening, high density dislocation strengthening and load transfer strengthening provided by Al 3 BC, and its excellent plasticity is attributed to the grain refinement and the excellent deformation coordination of the Al 3 BC clusters as strengthening units.