Abstract. Grain refinement plays a crucial role in improving characteristics and properties of cast and
wrought aluminium alloys. Generally Al–Ti and Al–Ti–B master alloys are added to the aluminium alloys to
grain refine the solidified product. The mechanism of grain refinement is of considerable controversy in the
scientific literature. The nucleant effects i.e. which particle and its characteristics nucleate a-Al, has been the
subject of intensive research. Lately the solute effect i.e. the effect of dissolved titanium on grain refinement,
has come into forefront of grain refinement research. The present paper attempts to review the literature on the
nucleant effects and solute effects on grain refinement and addresses the importance of dissolved titanium in
promoting nucleation of a-Al on nucleant particles.