Engineering a More Efficient Zirconium Grain Refiner For Magnesium
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Zirconium is currently used as a grain refiner for high temperature magnesium alloys. However, currently around 1 wt% is used for grain refinement, and much of this is wasted as sludge due to settling, as zirconium has a density almost four times that of magnesium. Since a recent study suggested that only faceted particles were activated as nucleation sites during casting solidification, ECAE processing of a magnesium-15wt% zirconium grain refiner master alloy was attempted to try to increase the number of faceted particles. ECAE processing of the master alloy only resulted in a modest decrease in grain size, even though the percentage of faceted particles doubled as a result of ECAE processing, since only 1.6% of zirconium particles in the as-received master alloy were faceted and deemed to be likely nucleation sites. The results from this work provide insights for the future development of more efficient grain refiners.
author list (cited authors)
Viswanathan, S., Saha, P., Foley, D., & Hartwig, K. T.
Magnesium Technology 2011