Evolution of Nanoporous Surface Layers on Gas-Atomized Ti60Cu39Au1 Powders during Dealloying

Abstract

Nanoporous golf ball-shaped powders with a surface porous layer consisting of fcc Cu and Cu3Au phases have been fabricated by selectively dissolving gas-atomized Ti60Cu39Au1 powders in 0.13 M HF solution. The distribution profiles of the Ti2Cu and TiCu intermetallic phases and powder size play an important role of the propagation of the selective corrosion frontiers. The final nanoporous structure has a bimodal characteristic with a finer nanoporous structure at the ridges, and rougher structure at the shallow pits. The powders with a size of 18–75 m dealloy faster due to their high crystallinity and larger powder size, and these with a powder size of smaller than 18 m tend to deepen uniformly. The formation of the Cu3Au intermetallic phases and the finer nanoporous structure at the ridges proves that minor Au addition inhibits the fast diffusion of Cu adatoms and decreases surface diffusion by more than two orders. The evolution of the surface nanoporous structure with negative tree-like structures is considered to be controlled by a percolation dissolution mechanism.

Dealloying-Induced Zeolite-like Metal Framework of AB2 Laves Phase Intermetallic Electrocatalysts

“…The selective leaching for Sc in M Co 2 and M Ru 0.25 Co 1.75 ( M = Sc and Zr) series may induce a new type of open tunnel framework that is similar to the zeolite structure but with a metallic property (Figure S1). Unlike the random atomic arrangement in the alloy, the atomic distribution in an intermetallic compound is relatively ordered to a certain degree and removal of a specific element may produce a novel material with a unique crystal structure . For instance, MXene (e.g., Ti 3 C 2 ) is probably the most well-known case in recent years, which is a two-dimensional layered structure made from the dealloying of Al in the Max phase (e.g., Ti 3 AlC 2 ) .…”

“…Unlike the random atomic arrangement in the alloy, the atomic distribution in an intermetallic compound is relatively ordered to a certain degree and removal of a specific element may produce a novel material with a unique crystal structure. 47 For instance, MXene (e.g., Ti 3 C 2 ) is probably the most well-known case in recent years, which is a two-dimensional layered structure made from the dealloying of Al in the Max phase (e.g., Ti 3 AlC 2 ). 48 It was realized from powder XRD (Figure S7) that no other phase was observed besides the MCo 2 and MRu 0.25 Co 1.75 (M = Sc and Zr) series after CA measurement (over 12 h in 6.0 M KOH at a current density close to 100 mA/cm 2 ).…”

Nanoporous Quasi-High-Entropy Alloy Microspheres

“…Nanoporous materials usually possess a high specific surface area [9,10]. However, traditional methods for preparing porous metals cannot be mechanically duplicated to acquire nanoporous HEAs.…”