INTRODUCTION Semi-solid metal (SSM) processing is a unique manufacturing method to produce near-net shape products for variousindustrial applications [1]. The aim is to obtain a semi-solidstructure free of dendrites (which are formed by conventional liquid casting), with the solid present as nearly aspherical form as possible. This semi-solid mixture (like agel, or toothpaste) flows homogeneously, behaving as athixotropic fluid with viscosity depending on shear rate andfraction solid [2]. There are two different SSM processes:thixocasting and rheocasting. With thixocasting, a speciallyprepared billet of solid material with a globular microstructure is reheated into the semi-solid range and formed. Rheocasting involves preparation of a SSM slurry directly fromthe liquid, followed by a forming process such as high pressure die casting (HPDC). The increased costs associated withthixocasting (recycling of thixocast scrap and the necessityof an outside manufacturer for billet production) have resulted in rheocasting becoming the preferred semi-solidprocess