Ultrasound assisted in situ technique for the synthesis of particulate reinforced aluminum matrix composites

Clusters of particle-reinforcement and high porosity are usually present in the in situ particulate reinforced metal-matrix composites (MMCs) fabricated by conventional stir casting technique. We studied the effect of ultrasonic vibration on the microstructures of in situ particulate reinforced aluminum composites. The process involved the addition of titanium and graphite powders into the molten pure aluminum at 850 degrees C. In the meantime, high intensity ultrasonic vibration was applied into the melt to disperse in situ formed particles into the matrix. Microstructural characterization indicated that in situ formed Al3Ti and TiC particles were distributed uniformly in the matrix and a homogeneous microstructure with a low porosity was gotten due to the effects of ultrasonic stirring and degassing. An effective approach using high intensity ultrasonic vibration to optimize the microstructure of in situ particulate reinforced metal matrix composites was given firstly, and the mechanism of ultrasonic vibration was also discussed. (C) 2011 Elsevier Ltd. All rights reserved.