An improved practice to manufacture Al–Ti–B master alloys by reacting halide salts with molten aluminium

The well-established “halide salt” route was employed in the present work to produce Al–Ti–B grain refiner alloys with consistent, good properties. The holding step in the production cycle was revised, however, to avoid oxidation of the molten alloy which is believed to be responsible for the relatively low Ti recoveries and thus for the inadequate and inconsistent grain refining efficiency. Stirring during holding was found to degrade the grain refining properties when molten potassium aluminium fluride salt was left on the molten alloy to avoid excessive oxidation. Likewise, holding temperatures higher than 800 °C and holding times longer than 30 min both had an undesirable effect on the grain refining performance. The experimental Al–5Ti–1B grain refiner alloy produced according to the present method provided consistent and better overall grain refining performance.