Three-Dimensional Morphological and Chemical Evolution of Nanoporous Stainless Steel by Liquid Metal Dealloying

Abstract

Nanoporous materials, especially those fabricated by liquid metal dealloying processes, possess great potential in a wide range of applications due to their high surface area, bicontinuous structure with both open pores for transport and solid phase for conductivity or support, and low material cost. Here, we used X-ray nanotomography and X-ray fluorescence microscopy to reveal the three-dimensional (3D) morphology and elemental distribution within materials. Focusing on nanoporous stainless steel, we evaluated the 3D morphology of the dealloying front and established a quantitative processing-structure-property relationship at a later stage of dealloying. The morphological differences of samples created by liquid metal dealloying and aqueous dealloying methods were also discussed. We concluded that it is particularly important to consider the dealloying, coarsening, and densification mechanisms in influencing the performance-determining, critical 3D parameters, such as tortuosity, pore size, porosity, curvature, and interfacial shape.

A Review of Experimentally Informed Micromechanical Modeling of Nanoporous Metals: From Structural Descriptors to Predictive Structure–Property Relationships

“…Thereby, they concluded that one of the parameters is sufficient to characterize the structural size. As another material system, nanoporous stainless steel was analyzed by Zhao et al through liquid metal dealloying (LMD) using X-ray nano-tomography [77]. The authors report that the ISD plots are qualitatively similar to the ISDs of np-Au.…”

Versatile compact heater design forin situnano-tomography by transmission X-ray microscopy

“…This structure continues to corrode and forms a bicontinuous 3D network of pores by 33 min [Fig. 3(c)], analogous to the dealloying process which forms nanoand meso-porous structures for functional applications (Erlebacher et al, 2001;Zhao et al, 2017Zhao et al, , 2019Chen-Wiegart et al, 2013). The corrosion process slows in 33-185 min [Figs.…”

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography

“…One solution to this is to dealloy parent alloys in a metallic melt, as studied in pioneering work by Harrison et al in the context of preferential leaching 26 . This liquid metal dealloying (LMD) has been more recently applied to form a range of porous structures including creating porous Ti out of Ti–Cu alloy 27 , 28 , porous Fe/Fe-alloys 29 – 31 using molten Mg, Ta, and Nb from their Ti-alloys using molten Cu 7 , 32 , and TiVNbMoTa nanoporous high entropy alloys 33 . With this method, the enthalpy of mixing is used to choose a system where the sacrificial metal (B) in a parent alloy (A–B) is miscible with the LMD agent (C), while the remaining metal is immiscible with the dealloying agent.…”