Preparation, microstructures and mechanical properties of in-situ TiB₂/Al composites by mechanical stirring and subsequent ultrasonic treatment

In this work, in situ TiB₂/2024Al composites were successfully fabricated by mechanical stirring and subsequent ultrasonic treatment. The effects of reaction temperature and enhanced phase mass fraction on the microstructure and mechanical properties of TiB₂/2024Al composites were studied. The results show that the reaction temperature affects the degree of reaction of the Al-Ti phase. When the reaction temperature is too low, a sheet-like Al-Ti intermediate phase still exists inside the melt. However, when the reaction temperature reaches 850 °C, the Al-Ti phase is dissolved sufficiently and evolves into TiB₂ particles. The ability of TiB₂ particles to refine matrix structure was also discussed. As the mass fraction of TiB₂ particles increases, the matrix structure is continuously refined. When compared to the base alloy, the yield strength, tensile strength and elongation are significantly improved. (paper)