Ladle Metallurgy of Aluminium-Silicon Alloy with Hybrid Modifiers

Aluminium-Silicon (Al-Si) alloy has been regarded as an alloy system that prefers brittle mode of fracture. The brittleness of the alloy can be attributed to the sharp needle-like eutectic Si and hard brittle β-Fe phase that deteriorates the mechanical properties of the alloy. In an attempt to impro...

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Bibliographic Details
Main Author: Kong, Hao Jie
Format: Thesis
Published: 2015
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Summary:Aluminium-Silicon (Al-Si) alloy has been regarded as an alloy system that prefers brittle mode of fracture. The brittleness of the alloy can be attributed to the sharp needle-like eutectic Si and hard brittle β-Fe phase that deteriorates the mechanical properties of the alloy. In an attempt to improve the microstructure of the Al-Si alloy, in this study, six combinations of hybrid modifiers (at 0.02wt.%), namely, Sodium-Boron (Na-B), Sodium-Titanium (Na-Ti), Strontium-Boron (Sr-B), Sodium-Strontium (Na-Sr), Strontium-Titanium (Sr-Ti), and Titanium-Boron (Ti-B) were added to the base Al-Si alloy (unmodified LM6). The addition of hybrid modifiers was performed outside the furnace, through ladle metallurgy. A systematic study was performed to study the density, microstructure, hardness, and tensile properties of the unmodified and hybrid modified LM6. In the density test conducted through Achimedes’ principle, Na-based hybrid modified LM6, such as Na-B and Na-Ti achieved the highest density at 2.747g/cm3. The result tallies with the greatest hardness measured in these alloys among the rest.