MODIFICATION OF ALUMINUM ALLOYS USING MASTER ALLOYS WITH DISPERSE INTERMETALLIDES

摘要

Numerous works by USSR and foreign researchers have established that the greatest modifying effect is possessed by master alloys with disperse intermetallide-modifiers, which are introduced in the form of rods under continuous casting of metal to ingots. According.to data in [1], it is believed that for TiB_2 particles larger than 20 ÷15 mu m, the effect of grain grinding is sharply reduced when using AI-Ti and Al-Ti-B master alloys. Research by the Kawecki-Billiton company indicated that TiB_2 particles, > 10 mum in size, are not crystallization centers. According to [2] the greatest modifying effect occurs when using material with refractory inclusions having a dispersion <5 mum. It follows from an earlier study [3] that in an ideal case, each TiB_2 particle should be spherical with a diameter of 1 mum. However, the literature contains no experimental data on modification with master alloys AI-Ti and AI-Ti-B - having disperse intermetallides (<1 mum).