From liquid metal dealloying to liquid metal expulsion
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From liquid metal dealloying to liquid metal expulsion Jun-Chao Shao1,* 1
and Hai-Jun Jin1
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, People’s Republic of China
Received: 18 February 2020
ABSTRACT
Accepted: 23 March 2020
In liquid metal dealloying, it is assumed that the corrosion product (dealloyed porous solids) is wetted by the liquid metal; otherwise, the dealloying may be halted due to liquid metal expulsion. Here, we report the first observation of liquid metal expulsion in liquid metal dealloying—liquid Ga rushes out of porous C when the dealloying of Mn–C alloy in liquid Ga is complete. On the contrary, similar to all previous reports, liquid Ga is trapped in porous Pb when In–Pb is dealloyed in liquid Ga. It suggests that liquid metal dealloying can proceed although the corrosion product is repelled by the liquid metal. Our study also reveals that the wettability and solid/liquid interface significantly influence the morphology of dealloyed porous structure, which has been largely unexplored in dealloying.
Published online: 2 April 2020
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Introduction Dealloying is a corrosion process that can generate nanoporous or porous materials [1–3] for many novel applications [4–10]. During dealloying, some elements are selectively dissolved from a precursor alloy, while the rest (un-etchable elements) are reorganized into a skeleton structure. In the conventional sense, dealloying is associated with the electrochemical or chemical corrosion in electrolytes, which involves charge transfer through oxidation and reduction processes. Recently, the concept of dealloying has been extended further largely by adopting the concept of ‘‘selective etching’’ but discarding the requirement of ‘‘charge transfer’’ [11–13], and even extended to peritectic melting [14]. Among them, liquid metal dealloying (LMD) has been most widely explored for generating bi-continuous Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10853-020-04599-2
composites and porous materials, for mechanical and functional applications [11, 15–17]. It is obvious that in LMD, the precursor alloy must be wetted by the liquid metal (for example, through reactive wetting); otherwise, the dealloying would not start. However, it remains unclear whether and how the dealloying is influenced by the wettability between liquid metal and corrosion product (dealloyed porous material). Most previous studies on LMD have been conducted in liquid Mg [18–21], Bi [22, 23], Cu [24–27], or the melt of their alloys (for lowering melting temperature) [28]. In all these cases, after dealloying, liquid metals are trapped in the dealloyed porous materials and solidified in place after cooling to room temperature. Chemical or electrochemical dissolution is thus needed to remove one phase to expose the skeleton of the other for specific applications. This indicates that in all these
8338 cases, the
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