Electrocapillary-Driven Metal Expulsion in Post-Transition Metal-Based Liquid Alloys

Alloying is a spontaneous process governed by the intrinsic miscibility of metal atoms. The reverse process of dealloying miscible metals through direct physical means is challenging to achieve. Here, a novel physical process is reported for the direct separation of solute metals from liquid alloys. The findings show that electrocapillary in Ga─Sn─Bi─Pb liquid alloy can lead to the selective expulsion of Bi, Sn, or Pb from the alloy surface as pure metals. The metals are expelled sequentially from the alloy with Bi first, followed by Sn, and then Pb. Theoretical calculations suggest that the sequence of expulsion is primarily determined by the surface energy of solute metals. A metallurgical process based on this phenomenon is proposed and evaluated as a viable approach for refining post-transition metals. This study presents innovative insights that lay the foundation for developing reliable low-energy metallurgical techniques to separate metals based on differences in their surface energy.