Acoustic-Cavitation-Based Production of Foamed Metallic Material

概要

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Two trial experiments on the ultrasonic solidification of a metal have been carried out to develop an innovative technique to produce foamed metallic materials by trapping acoustic cavitation multibubble in a solidified metal. Wood's alloy that is a bismuth-based quaternary eutectic alloy having a low melting point is employed in the experiments. The first experiment is devoted to the continuous casting of Wood's alloy under an indirect irradiation of ultrasound at a frequency of 20 kHz. Continuously refined microstructures of Wood's alloy are observed by scanning electron microscopy (SEM). The second experiment is carried out for casting Wood's alloy under a direct irradiation of ultrasound at a frequency of 20 kHz. It is confirmed by SEM and energy-dispersive X-ray spectroscopy (EDS) that acoustic cavitation multibubble can be trapped as uniformly distributed nanoscale voids only in Cd-rich eutectic microstructures. This result is attributed to the finding that the Cd-rich microstructure is the primary crystal and Cd is the element having the highest vapor pressure in the quaternary system. All results suggest that the production of foamed materials by the trapping of acoustic cavitation multibubble is possible with irradiating ultrasound at the appropriate frequency and power.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2006-05-30