Tohoku University · Materials Science
Professor Soo-Hyun Joo's research lab specializes in the design and synthesis of advanced nanostructured metallic materials, with a focus on liquid metal dealloying (LMD) and high-entropy alloys (HEAs). The lab explores innovative strategies to control nanoscale morphology, phase stability, and mechanical properties in three-dimensional interconnected porous and cellular materials for applications in catalysis, energy systems, and structural components. Key research directions include the development of crack-free nanocellular graphene, strengthening of low-melting-point metal phases via eutectic alloying, and engineering deformation mechanisms in bulk metallic glasses through severe plastic deformation.
Figures are computed from collected data and may differ slightly.
Controlling the feature sizes of 3D bicontinuous nanoporous (3DNP) materials is essential for their advanced applications in catalysis, sensing, energy systems, etc., requiring high specific surface area. However, the intrinsic coarsening of nanoporous materials naturally reduces their surface energy leading to the deterioration of physical properties over time, even at ambient temperatures. A novel 3DNP material beating the universal relationship of thermal coarsening is reported via high-entro
The mechanical properties of engineering materials are key for ensuring safety and reliability. However, the plastic deformation of BMGs is confined to narrow regions in shear bands, which usually result in limited ductilities and catastrophic failures at low homologous temperatures. The quasi-brittle failure and lack of tensile ductility undercut the potential applications of BMGs. In this report, we present clear tensile ductility in a Zr-based BMG via a high-pressure torsion (HPT) process. En
Liquid metal dealloying is a promising technique for synthesizing non-noble porous materials by preventing oxidation in a metallic melt. This method considers the heats of mixing between precursor elements and a melt element to design miscible and immiscible elements for a precursor. In this study, Ni and Co were selected as the miscible elements in an Mg melt as constituents of (FeCo)100−xNix precursor alloys to understand the complex mechanisms of their dissolution behavior. Dissolution of the
Liquid metal dealloying (LMD) is a promising technique that can be used to synthesize non-noble porous materials by preventing oxidation through using a metallic melt. However, the phase transformation behavior between a parent grain and synthesized ligaments surrounded by penetrating liquid metal channels remains unknown, despite its importance on the final physical properties. In this study, the temperature effect on the transformation mechanisms during the LMD process is investigated. At a lo
Crack-free nanocellular graphenes are attractive materials with extraordinary mechanical and electrochemical properties, but their homogeneous synthesis on the centimeter scale is challenging. Here, a strong nanocellular graphene film achieved by the self-organization of carbon atoms using liquid metal dealloying and employing a defect-free amorphous precursor is reported. This study demonstrates that a Bi melt strongly catalyzes the self-structuring of graphene layers at low processing temperat
Liquid metal dealloying (LMD) has recently attracted significant attention. Because the LMD process enables the production of three-dimensional (3D) interconnected non-noble metallic materials. In addition, the metallic melt medium is useful for the development of heterostructure (HS) metal–metal composites. However, the solidified liquid metal phase (low melting point metals such as Mg, Bi, Sn, or Cu) has a much lower strength than the developed ligament phase (e.g., Fe, FeCr, Ti, etc.). In thi
In this study, 3D interconnected nanoporous (3DNP) TiVNbMoTa HEAs were synthesized from the (TiVNbMoTa)25Ni75 as-cast precursor alloy using the liquid metal dealloying (LMD). The as-cast precursor demonstrated the initial dendritic microstructure consisting of fcc and hcp phases. At 600 °C after 1 h, tiny ligaments about 10 nm thickness were homogeneously synthesized. At 900 °C, the bulk transformation intensively took place at the original precursor alloy. Specifically, the dendritic morphology
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