A comparative study of iron, cobalt or cerium micro-alloying on microstructure and apparent viscosity of Al-5Ni alloy

The micro-alloying is promising in improving the mechanical properties, thermal conductivity, and castability of the near-eutectic Al-Ni alloys, enabling them to be formed via the special casting or additive manufacturing technique. But the rheological behavior of the molten near-eutectic Al-Ni alloys is not clear. The present work investigates the effect of three kinds of micro-alloying agents (iron, cobalt, and cerium) at 0.3 wt% on the solidification and rheological behaviors of the Al-5Ni alloy. Results indicate that the addition of the micro-alloying element can significantly refine the <<-Al grains in the Al-5Ni alloy, leading to the improvement of the thermal conductivity and mechanical properties. The cooling curves thermal analysis suggests that the incorporated micro-alloying element can notably change the cooling rate of the melts during the solidification course. Phase-field simulations illustrate that the different cooling rates cause the change of the shape factor and the fraction of <<-Al grains during the solidification course of the alloy, leading to the remarkable difference of the viscosities at different temperatures and shear rates of the Al5Ni melts. This work provides an in-depth understanding of the correlation between the solidification route and rheological behavior of the Al-5Ni melts with micro-alloying treatment. (c) 2023 Elsevier B.V. All rights reserved.