Chemical and Materials Engineering Vol. 1(3), pp. 69 - 73
DOI: 10.13189/cme.2013.010301
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The Influence of Ultrasonic Stirring on the Solidification Microstructure and Mechanical Properties of A356 Alloy


S. Jia, L. Nastac*
The University of Alabama, Department of Metallurgical and Materials Engineering, Box 870202, Tuscaloosa, Alabama, 35487, United States

ABSTRACT

Ultrasonic treatment has significant effects on the solidified microstructure, which includes grain structure, distribution of inclusions, refinement of secondary phases, etc. The primary causes are due to ultrasonic cavitation, acoustic streaming and movement of dislocations associated with propagation of ultrasound waves in media. However, the mechanism of how those effects happen are not fully understood and quantified. In this research, molten A356 alloy was treated with high power ultrasound at a frequency of 18 kHz, and then at relatively high superheat, the melt was cast into a permanent metal mold which complies with ASTM B108-02. The relatively high superheat condition is similar to one used in the standard foundry practice. The selected parameters for the ultrasonic stirring technology (UST) were determined by using a UST model that was recently developed and validated. The ultrasonically-stirred A356 alloy shows superior microstructure characteristics with very low micro-porosity levels. The microstructure and mechanical properties of the A356 alloy processed with and without UST were analyzed and compared in detail in this paper.

KEYWORDS
Ultrasonic Processing, Ultrasonic Cavitation and Acoustic Streaming, Aluminum Alloys, Microstructure, Mechanical Properties

Cite this paper
S. Jia , L. Nastac (2013). The Influence of Ultrasonic Stirring on the Solidification Microstructure and Mechanical Properties of A356 Alloy. Chemical and Materials Engineering, 1 , 69 - 73. doi: 10.13189/cme.2013.010301.