Effect of ultrasonic processing duration on the microstructure evolution and applied performance of ternary Cu-Sn-Bi immiscible alloy

Three-dimensional (3D) orthogonal ultrasounds were introduced into ternary Cu-33%Sn-15%Bi immiscible alloy to control its liquid-phase separation. Compared to the layered structure formed under static condition, homogeneous dispersion of Bi-rich particles within the Cu₃Sn matrix was facilitated by employing short-time ultrasounds during the final stage of liquid-phase separation. Conversely, long-time ultrasounds application throughout liquid-phase separation generated limited macro-segregation suppression effect. Numerical simulations indicated that although long-time ultrasounds enhanced droplet nucleation, it also induced significant acoustic shielding from cavitation bubbles, causing severe attenuation of acoustic energy and consequent reduction in droplet fragmentation and migration. This phenomenon weakened the fragmentation and the migration of Bi droplets. The homogeneous and refined microstructure produced by short-time 3D ultrasounds possessed superior electrochemical corrosion and wear-resisting properties. This work demonstrates that employing an appropriate ultrasonic processing time can inhibit cavitation-induced acoustic shielding and maximize energy utilization efficiency.