Grain refinement of Al-3.5FeNb-1.5C master alloy on pure Al and Al-9.8Si-3.4Cu alloy

Abstract

The refinement potential of Al-3.5FeNb-1.5C master alloy on pure aluminium and Al-9.8Si-3.4Cu alloy has been investigated. Different amounts of Al-3.5FeNb-1.5C master alloy were added to estimate the optimal addition level. It was found that the addition of Al-3.5FeNb-1.5C grain refiner can promote significantly the refinement of grains in the pure aluminium, particularly at 0.1wt.%, with the mean primary aluminium α-grain size reducing to 187±3 μm from about 1–3 mm. Similarly, the microstructural study of the Al-9.8Si-3.4Cu alloy die casting at different weight percentages (viz. 0.0wt.%, 0.1wt.% and 1.0wt.%) of Al-3.5FeNb-1.5C master alloy shows that the Al-3.5FeNb-1.5C master alloy as a grain refiner is also acceptable for Al-Si cast alloys when the silicon content is more than 4wt.%. As a result of inoculation with Al-3.5FeNb-1.5C master alloy, the average grain size of α-Al is reduced to 22±3 μm from about 71±3 μm and grain refining efficiency is not characterized by any visible poisoning effect, which is the major limitation in the grain refinement of Al-Si cast alloys by applying Al-Ti-B ternary master alloys. Mechanical properties such as ultimate tensile strength and yield strength are significantly improved by 9.6% and 9.7%, respectively.