Three orthogonal ultrasounds fabricate uniform ternary Al-Sn-Cu immiscible alloy

Abstract

The production of Al based monotectic alloys with uniform microstructure is usually difficult due to the large density difference between the two immiscible liquid phases, which limits the application of such alloys. Here, we apply three orthogonal ultrasounds during the liquid phase separation process of ternary Al71.9Sn20.4Cu7.7 immiscible alloy. A uniform microstructure consisting of fine secondary (Sn) phase dispersed on Al-rich matrix is fabricated in the whole alloy sample with a large size of 30 × 30 × 100 mm. The numerical calculation results indicate that the coupled effect of three ultrasounds promotes the sound pressure level and consequently enlarges the cavitation zone within the alloy melt. The strong shockwaves produced by cavitation prevent the (Sn) droplets from coalescence, and keep them suspended in the parent Al-rich liquid phase. This accounts for the formation of homogeneous composite structures. Thus the introduction of three orthogonal ultrasounds is an effective way to suppress the macrosegregation caused by liquid phase separation and produce bulk immiscible alloys with uniform structures.

High-Frequency Vibration and Ultrasonic Processing

“…It was also observed that the monotectic cells nucleate on cavitation-affected substrates. An innovative scheme of ultrasonic processing with three orthogonal sources was developed and applied to the solidification of a similar immiscible alloy [127]. In this case the homogeneous monotectic structure was obtained in the entire 30×30×100 mm volume, due to the uniform cavitation field created in the melt.…”