Investigation of the clustering behaviour of titanium diboride particles in aluminium

The clustering of reinforcement particles in cast metal matrix composite (MMC) material has a number of deleterious effects on its mechanical properties and castability. In order to better understand this phenomenon, the clustering behaviour of TiB2 particles in molten commercial purity aluminium was investigated. A novel method of sampling the melt was developed in order to investigate the clustering behaviour as a function of holding time at 700 degrees C. The initially clustered distribution of TiB2 became increasingly dispersed with increased holding time. The maximum observed cluster size decreased from 50 to 10 mu m after a holding period of 73 h. X-ray microtomography (XMT) and SEM micrograph analyses were carried out to quantify the rate of dispersion of the clusters. XMT was shown to be a powerful tool for visualizing and quantifying 3-dimensional features within the MMC microstructure. (c) 2005 Elsevier Ltd. All rights reserved.