Process of refining the grain size of hypereutectic aluminium silicon alloys

摘要

Hypereutectic aluminium-silicon alloys are grain refined by introducing phosphorus aluminide and a halogen in the melt. Both components may be generated in the melt, the compound by adding a mixture of powdered aluminium and a phosphorus compound and the halogen by thermal decomposition of hexachloroethane in the melt. If an elemental halogen is added it is preferably chlorine gas. The phosphorus-containing mixtures can be added as briquettes or in aluminium tubes. The halogen can be added at any time subsequent to the addition of the phosphorus aluminide and melts that stand for a time can be reactivated when needed by the addition of more halogen. The following alloy is treated as above set forth:-Si 23 per cent, Cu 1 per cent, Mg 1 per cent, Ni 1 per cent, Fe 0.4 per cent, Mn 0.2 per cent, Ti 0.2 per cent, Al balance.