Challenges and Opportunities for Integrating Dealloying Methods into Additive Manufacturing

Abstract

The physical architecture of materials plays an integral role in determining material properties and functionality. While many processing techniques now exist for fabricating parts of any shape or size, a couple of techniques have emerged as facile and effective methods for creating unique structures: dealloying and additive manufacturing. This review discusses progress and challenges in the integration of dealloying techniques with the additive manufacturing (AM) platform to take advantage of the material processing capabilities established by each field. These methods are uniquely complementary: not only can we use AM to make nanoporous metals of complex, customized shapes—for instance, with applications in biomedical implants and microfluidics—but dealloying can occur simultaneously during AM to produce unique composite materials with nanoscale features of two interpenetrating phases. We discuss the experimental challenges of implementing these processing methods and how future efforts could be directed to address these difficulties. Our premise is that combining these synergistic techniques offers both new avenues for creating 3D functional materials and new functional materials that cannot be synthesized any other way. Dealloying and AM will continue to grow both independently and together as the materials community realizes the potential of this compelling combination.

How Can We Efficiently Fabricate Nanostructured Materials with Unprecedented Properties?

“…For structural materials, one particularly high-impact fabrication area is powder metallurgy (e.g., hot isostatic pressing, thermal spray, or additive manufacturing). 24 These processes are all near net-shape fabrication, which has challenges in achieving the traditional degree of microstructural control offered by forging. Liquid metal dealloying can address this shortcoming by providing a means to tailor the microstructure at the nanoscale with seamless integration.…”

“…Three key research areas to realize true nanoscale control via self-organization processes: (bottom) extension of these tools to any material class; , (left) manipulating kinetic and thermodynamic factors during self-organization to control the resulting nanoscale morphology; , (right) sequential self-organization and post processing protocols to develop multiscale nanocomposites. , Images adapted with permission from refs (Copyright 2014 American Chemical Society), (Copyright 2021 Elsevier), (Copyright 2021 The American Association for the Advancement of Science), (Copyright 2016 John Wiley and Sons), and (Copyright 2021 John Wiley and Sons).…”

Electroless Dealloying of Thin-Film Nanocrystalline Au–Ag Alloys: Mechanisms of Ligament Nucleation and Sources of Its Synthesis Variability

“…While, in electrolysis, both external bias and current density can provide in situ process monitoring to standardize its synthesis, it is the electroless method of dealloying that is most popular in academia and industry due to its facile implementation (i.e., does not require electronic hardware) and easy integration with nonconductive substrates in nanofabrication processes. It is also the only compatible method for dealloying of powder precursors which are most suitable for and have applications in additive manufacturing . However, electroless methods not only lack standardization, but also yield large variability whose sources have not been understood and, thus, it hinders knowledge transfer across research groups and commercialization efforts.…”

“…26 Therefore, the control of its morphology with high degree of accuracy and repeatability is desired for establishing robust process−structure relationships. While, in electrolysis, both external bias and current density can provide in situ process monitoring to standardize its synthesis, 27 it is the electroless method of dealloying that is most popular in academia 28 and industry due to its facile implementation (i.e., does not require electronic hardware) and easy integration with nonconductive substrates in nanofabrication processes. It is also the only compatible method for dealloying of powder precursors which are most suitable for and have applications in additive manufacturing.…”

Recent Advancements in the Fabrication of Functional Nanoporous Materials and Their Biomedical Applications

“…These strategies have been used to fabricate ordered, disordered, and hierarchical nanoporous materials with tunable pore sizes, shapes, and relative orientation of pores at different length scales. In recent years, several reviews published on nanoporous materials have primarily focused on selective modification of nanoporous materials, synthesis, and characterization of specific types of nanoporous materials and their applications [ 8 , 17 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. Indeed, the field of nanoporous materials is progressing at a rapid pace with more emphasis on developing new fabrication strategies.…”