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.