Abstract
The results inferred from the present work show that Al3Ti phase has a strong affinity to react with silicon (Si) in the molten alloy leading to formation of (Al,Si)3Ti phase instead. This reaction is independent of the grain refiner type. The molten liquid temperature would change its morphology from platelets at 750°C into dendritic structure at 950°C. It has also been observed that (Al,Si)3Ti phase platelets precipitate within theα-aluminum dendrites, whereas TiB2or AlB2particles are released into the surrounding interdendritic regions. Introduction of the grain refiner, regardless its type, would cause change in theα-aluminum dendrite morphology from an elongated to a more rounded form. The results also reveal that addition of 100 ppm B will reduce the initial grain size by ∼85% which is more than the effect of addition of 0.2%Ti in the form of Al-10%Ti (about 65%). Elimination of undercooling is important to obtain the maximum grain refining effect.
Highlights
Many theories have been proposed to explain the mechanism of grain refining
E results inferred from the present work show that Al3Ti phase has a strong affinity to react with silicon (Si) in the molten alloy leading to formation of (Al,Si)3Ti phase instead. is reaction is independent of the grain refiner type. e molten liquid temperature would change its morphology from platelets at 750°C into dendritic structure at 90 min (750°C) min (950°C)
When a master alloy containing Al-Ti-B is added to molten metal such that the amount of Ti is less than 0.15%, often boron particles are found at the centers of the grains, with dendrites enriched in titanium growing outside of the grains
Summary
Effect of Melt Temperature on the Effectiveness of the Grain Refining in Al-Si Castings. Is reaction is independent of the grain refiner type. E molten liquid temperature would change its morphology from platelets at 750°C into dendritic structure at 950°C. It has been observed that (Al,Si)3Ti phase platelets precipitate within the α-aluminum dendrites, whereas TiB2 or AlB2 particles are released into the surrounding interdendritic regions. Introduction of the grain refiner, regardless its type, would cause change in the α-aluminum dendrite morphology from an elongated to a more rounded form. E results reveal that addition of 100 ppm B will reduce the initial grain size by ∼85% which is more than the effect of addition of 0.2%Ti in the form of Al-10%Ti (about 65%). Elimination of undercooling is important to obtain the maximum grain refining effect
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