The role of ultrasonic cavitation in refining the microstructure of aluminum based nanocomposites during the solidification process

Yang Xuan; Laurentiu Nastac

doi:10.1016/j.ultras.2017.06.023

The role of ultrasonic cavitation in refining the microstructure of aluminum based nanocomposites during the solidification process

Ultrasonics. 2018 Feb:83:94-102. doi: 10.1016/j.ultras.2017.06.023. Epub 2017 Jul 1.

Authors

Yang Xuan¹, Laurentiu Nastac²

Affiliations

¹ The University of Alabama, Department of Metallurgical and Materials Engineering, Box 870202, Tuscaloosa, AL 35487, USA.
² The University of Alabama, Department of Metallurgical and Materials Engineering, Box 870202, Tuscaloosa, AL 35487, USA. Electronic address: lnastac@eng.ua.edu.

PMID: 28693864
DOI: 10.1016/j.ultras.2017.06.023

Abstract

Recent studies showed that the microstructure and mechanical properties of aluminum based nanocomposites can be significantly improved when ultrasonic cavitation and solidification processing is used. This is because ultrasonic cavitation processing plays an important role not only in degassing and dispersion of the nanoparticles, but also in breaking up the dendritic grains and refining the as-cast microstructure. In the present study, A356 alloy and Al₂O₃ nanoparticles are used as the matrix alloy and the reinforcement, respectively. Nanoparticles were added into the molten A356 alloy and dispersed via ultrasonic cavitation processing. Ultrasonic cavitation was applied over various temperature ranges during molten alloy cooling and solidification to investigate the grain structure formation and the nanoparticle dispersion behavior. Optical Microscopy and Scanning Electron Microscopy were used to investigate in detail the differences in the microstructure characteristics and the nanoparticle distribution. Experimental results indicated that the ultrasonic cavitation processing and Al₂O₃ nanoparticles play an important role for microstructure refinement. In addition, it was shown in this study that the Al₂O₃ nanoparticles modified the eutectic phase.

Keywords: A356-matrix-nanocomposites; Al(2)O(3) nanoparticles; Eutectic modification; Grain refinement; Microstructure; Solidification processing; Ultrasonic cavitation processing.