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 °C. The initially clustered distribution of TiB2 became increasingly dispersed with increased holding time. The maximum observed cluster size decreased from 50 to 10 μm 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.