Understanding dual-frequency ultrasonic melt treatment on grain refinement and mechanical properties improvement of AZ80 magnesium alloy: experiment and simulation

Abstract

This work investigated the acoustic pressure distribution and relevant cavitation area of the dual-frequency ultrasonic field (DUF) in magnesium melt using numerical simulation. Associated experiments were also implemented to understand the grain refinement of DUF. DUF weakens the acoustic attenuation and then enlarges the potential cavitation area than the single-frequency ultrasonic field (SUF). Such improvement promotes its grain refinement efficiency, which is 17.7% and 24% higher than 15 kHz and 20 kHz SUF, respectively. Both yield strength and ultimate tensile strength are improved by DUF melt treatment. The improvement of mechanical properties for ultrasonic melt treated alloy is attributed to the grain refinement and the texture evolution. To optimize the grain refinement of DUF melt treatment, choosing the appropriate input acoustic pressure ratio is important. Under the premise of relevant symmetrical distribution of the cavitation area, increasing the acoustic pressure input for 15 kHz ultrasonic is beneficial to improve the grain refinement efficiency.

Keywords

• Ultrasonic melt treatment
• Magnesium alloy
• Numerical Simulation
• Grain refinement
• Cavitation