Effect of grain refinement on the fluidity of some binary Al—Cu and Al—Mg alloys

The effect of grain refining, by AlTi5B1 master alloy additions, on the fluidity of two binary Al—Cu and Al—Mg alloys has been assessed using a vacuum fluidity test apparatus. Five levels of grain refinement were investigated in each alloy: AlMg1, AlMg5, AlCu2 and AlCu4. In AlCu4 and AlMg5, fluidity initially decreased with increasing grain refinement, reaching a minimum at 0.03 wt% Ti. Increasing the grain refinement above this level did not give any significant increase in fluidity. In AlMg1, the minimum was displaced to 0.05 wt% Ti. Fluidity decreased continuously with increasing grain refinement in the AlCu2 alloy. However, for all alloys, the fluidity was lower at the highest grain refiner content than in the unrefined alloy. Increasing the content of the major alloy element decreased the fluidity.