AGGLOMERATION AND SETTLEMENT OF TiB2 PARTICLES IN MOLTEN ALUMINIUM.

Agglomeration of TiB//2 particles, if they are present in the melt, can lead to contamination of the furnace; in the casting, they impair the surface. The investigation is intended, therefore, to clarify definitely the formation and behavior of TiB//2 particles during grain refining ith Al-Ti-B. Thus it has been shown that TiB//2 agglomerates increasingly with advancing holding time and that the particles settle donwards; in this way the grain refining effect is reduced. The process increases in speed as more grain refiner is added. The type of grain refiner has a considerable influence on the grain refining effect. Al-5%Ti-1%B, for which the size of the TiB//2 particles is largely unaffected by holding time, gave the best effect.