Ultrasonic processing of lightweight alloys: A critical review

Abstract

Ultrasonic processing in the liquid state has been identified as an effective method to improve the mechanical properties of Al and Mg alloys. Ultrasonic melt processing is capable of enhancing material properties through the application of high-frequency, high-power vibrations that form cavitation bubbles which pulsate and collapse throughout the melt volume. Thus, this technology has excellent potential in engineering high performance lightweight materials. With global trends converging toward greener energy, reduced greenhouse gas (GHG) emissions and increasingly stringent efficiency standards, lightweight and high-strength alloys such as aluminum (Al) and magnesium (Mg) are becoming an area of high interest. The aim of this review is to analyze the literature on ultrasonic processing of Al and Mg alloys in the last 15 years. This review discusses ultrasonic processing equipment, experimental set-ups, mechanisms of ultrasonic cavitation and acoustic streaming. As well, the effects of processing time, vibrational amplitude, and temperature on microstructure and properties are elucidated. Furthermore, it aims to investigate how a combination of sonication and particle reinforcement can affect the properties of Al and Mg alloys. The challenges of ultrasonic processing have been identified and expanded on in this review. This includes energy consumption, equipment complexity, temperature control, process optimization and limited industrial adoption.