Controlling mechanical and physical properties of Al-Si alloys by controlling grain size through grain refinement and electromagnetic stirring

The present study concerns the influence of a travelling magnetic field (TMF) on the hardness, tensile strength and electrical conductivity of directionally solidified grain-refined and non-refined Al-7 wt.% Si alloys. Upwards and downwards travelling fields have been applied to force convection within the solidifying melt. Modifications of the examined physical and mechanical properties depend on the formation of a fine equiaxed structure caused by both the addition of grain refining AlTi5B1-particles and by electromagnetic stirring as well. Electromagnetic stirring without grain refining particles leads to an increase in tensile strength. The addition of grain refiners into the melt leads to the highest reduction of the mean grain size and results in a decrease in electrical conductivity. A melt stirring by a sufficiently high magnetic field provides a homogeneous grain size distribution in the sample volume which impacts the distribution of hardness, tensile strength and electrical conductivity.