Microstructure Modification for Cu–TiB2 Composites by Ultrasonic Power-Assisted in Situ Casting

Abstract

Ultrasonic vibration treatment (UVT) at varying power was successfully applied to the Cu–TiB₂ composite melt using a SiAlON ceramic sonotrode. The results indicate that TiB₂ particles are more evenly dispersed in the Cu matrix with increasing ultrasonic power, leading to improved mechanical properties of as-cast composites (≤ 1000 W). With 1000 W UVT, the distribution of TiB₂ particles becomes the remarkably uniform and well dispersed, with the size of TiB₂ particle aggregates decreasing from ~ 50 μm without UVT to ~ 5 μm. The ultimate tensile strength, yield strength, and elongation of the as-cast composite are 201 MPa, 85 MPa, and 28.6%, respectively, representing increases of 21.1%, 27.3%, and 43%, respectively, compared to the as-cast composite without UVT. However, when the power is increased to 1500 W, thermal effects are likely to emerge, and the ultrasonic attenuation effect is enhanced, resulting in the re-agglomeration of TiB₂ particles and a deterioration in performance. By quantitatively analyzing the relationships between sound pressure (P_k), sound energy density (I), sound pulse velocity (V), and ultrasonic power, the influence mechanism of ultrasonic power on the composite microstructure has been further elucidated and characterized. This study provides crucial guidance for the industrial application of UVT in the fabrication of Cu matrix composites.