Quantities of grains of aluminum and those of TiB2 and Al3Ti particles added in the grain-refining processes

Al-Ti-B alloys are the most commonly used grain-refiners in the casting of aluminum alloys: however, the grain-refining mechanisms are still not conclusive. Quantities of the two kinds of phase particles. TiB2 and Al3Ti, introduced into the molten aluminum by the addition of Al-Ti-B grain refiners are determined experimentally. It is found that the quantities of Al3Ti particles introduced are much lower than those of grains in the as-cast aluminum alloys, while those of introduced TiB2 are higher. Thus it is concluded the Al3Ti particles in the Al-Ti-B grain-refiners cannot be the primary nucleation sites during solidification of aluminum. (C) 2002 Elsevier Science B.V. All rights reserved.