Stability of intermetallic aluminides in liquid aluminium and implications for grain refinement

Abstract

The behaviour of intermetallic aluminide particles in liquid aluminium is of importance in view of their postulated role in mechanisms of grain refinement by melt inoculation. The dissolution rates of Al₃Ti, Al₃Zr, and Al₃Nb have been investigatedfor a range of conditions. It is concluded that thermodynamic equilibrium is quickly established in the case of titanium, but takes much longer for niobium, with zirconium apparently exhibiting behaviour intermediate between these two extremes. This result is correlated with observations on grain refinement and the probable mechanisms responsible for these effects are discussed.