METHOD FOR PRODUCING AN ALUMINUM-TITANIUM-BORON PREALLOY FOR USE AS A GRAIN REFINER

摘要

The invention relates to a method for producing a grain refiner on the basis of an aluminum-titanium-boron prealloy. According to the inventive method, starting materials that contain Ti and B are introduced into an aluminum melt while TiB2 particles are formed, and the prealloy melt produced is allowed to solidify. The prealloy is set in motion at a temperature between the liquidus temperature (TLAl3Ti) of the Al3Ti phase and the solidus temperature (TSV) of the prealloy for a period (Δtd) sufficient to disperse the TiB2 particles in the melt. The melt is simultaneously cooled off at a first rate of cooling (v1) so that the TiB2 particles function as the nuclei for the Al3Ti phase that is formed below the liquidus temperature (TLAl3Ti) and the surface of the TiB2 particles is at least partially covered by an Al3Ti coating. The prealloy is then cooled off to a temperature below the solidus temperature (TSV) of the prealloy at a second rate of cooling (v2) that is higher than the first rate of cooling (v1). The inventive method is especially useful in the production of grain refiners for the grain refinement of aluminum and aluminum alloys.