Effect of cerium addition on microstructure, thermal and rheological properties of hypoeutectic Al-Ni alloy

The microstructure, mechanical properties, electrical/thermal conductivity, and rheological behavior of Al-5Ni alloy with different Ce contents were systematically investigated. The experimental results demonstrate that an appropriate addition of Ce reduces the recalescence and growth temperatures of the Al-Ni eutectic structure, resulting in a reduction in precipitation phase size and the formation of a spherical Al3Ni eutectic structure. It leads to improvement in electrical conductivity and mechanical properties. But excessive addition of Ce leads to the formation of slatted Al23Ce4Ni6 on the Al-Ni eutectic boundary, causing the samples with higher Ce content to exhibit lower strength and thermal conductivity. Additionally, the investigation of alloy viscosity indicates significant shear thinning behavior of Al-Ni alloys, which contributes to obtaining uniformly filled and good quality cast products. The variation of melt viscosity suggested that Ce elements could improve the morphology and distribution of & alpha;-Al precipitates in the alloy, leading to an increase in viscosity in a specific temperature range.