Microstructural evolution and mechanical properties of in situ TiB₂/Al composites under high-intensity ultrasound

Microstructural evolution and mechanical properties of in situ TiB₂/Al composites fabricated with exothermic reaction process under high-intensity ultrasound produced by the magnetostrictive transducer were investigated. In this method, the microstructure and grain refining performance of the TiB₂/Al composites were characterized by optical morphology (OM), scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), and X-ray diffraction (XRD) analysis. Microstructural observations show a decreasing trend in the grain size of the composites due to the ultrasound and the content of TiB₂ particles in the composites. Compared with the process without ultrasound, the morphology and agglomeration of TiB₂ particles are improved by high-intensity ultrasound. Meanwhile, it is proposed that the formation of TiB₂ particles occurs via the transformation from TiAl₃, and at the optimal amount of the reactants, the conversion efficiency of TiAl₃ into TiB₂ almost reaches up to 100 %. Finally, the effects of high-intensity ultrasound and TiB₂ particles on the mechanical properties of the TiB₂/Al composites were also discussed.