Dealloying of an amorphous TiCuRu alloy results in a nanostructured electrocatalyst for hydrogen evolution reaction

Development of an electrocatalyst that is cheap and has good properties to replace conventional noble metals is important for H_(2) applications.In this study,dealloying of an amorphous Ti_(37)Cu_(60)Ru_(3) alloy was performed to prepare a freestanding nanostructured hydrogen evolution reaction(HER)catalyst.The effect of dealloying and addition of Ru to TiCu alloys on the microstructure and HER properties under alkaline conditions was investigated.3 at.%Ru addition in Ti_(40)Cu_(60) decreases the overpotential to reach a current density of 10mA cm^(-2) and Tafel slope of the dealloyed samples to 35 and 34mV dec−1.The improvement of electrocatalytic properties was attributed to the formation of a nanostructure and the modification of the electronic structure of the catalyst.First-principles calculations based on density function theory indicate that Ru decreases the Gibbs free energy of water dissociation.This work presents a method to prepare an efficient electrocatalyst via dealloying of amorphous alloys.

块体金属玻璃

块体金属玻璃是一种典型的工程材料，它拥有比钢还要高的强度，同时能够像塑料一样模压和成形。

Multiscale patterning of a metallic glass using sacrificial imprint lithography

Bulk metallic glasses(BMGs)have been developed as a means to achieve durable multiscale,nanotextured surfaces with desirable properties dictated by topography for a multitude of applications.One barrier to this achievement is the lack of a bridging technique between macroscale thermoplastic forming and nanoimprint lithography,which arises from the difficulty and cost of generating controlled nanostructures on complex geometries using conventional top-down approaches.This difficulty is compounded by the necessary destruction of any resulting reentrant structures during rigid demolding.We have developed a generalized method to overcome this limitation by sacrificial template imprinting using zinc oxide(ZnO)nanostructures.It is established that such structures can be grown inexpensively and quickly with tunable morphologies on a wide variety of substrates out of solution,which we exploit to generate the nanoscale portion of the multiscale pattern through this bottom-up approach.In this way,we achieve metallic structures that simultaneously demonstrate features from the macroscale down to the nanoscale,requiring only the top-down fabrication of macro/microstructured molds.Upon detachment of the formed part from the multiscale molds,the ZnO remains embedded in the surface and can be removed by etching in mild conditions to both regenerate the mold and render the surface of the BMGs nanoporous.The ability to pattern metallic surfaces in a single step on length scales from centimeters down to nanometers is a critical step toward fabricating devices with complex shapes that rely on multiscale topography for their intended functions,such as biomedical and electrochemical applications.

Revealing the relationships between alloy structure,composition and plastic deformation in a ternary alloy system by a combinatorial approach

A high-throughput approach based on magnetron co-sputtering of alloy libraries is employed to investigate mechanical properties of crystalline and amorphous alloys in a ternary palladium(Pd)-tungsten(W)-silicon(Si)system with the aim to reveal the difference in plastic deformation response and extract the relevant structure-property relationships of the alloys in the system.It was found that in contrast to crystalline alloys,the amorphous ones,i.e.,metallic glasses,exhibited a much smaller fluctuation range in the plasticity parameters(Er2/H and Wp/Wt),indicating a significant difference in the plastic deformation mechanism controlling the mechanical properties for the respective alloys.We propose that the inhomogeneous deformation of amorphous alloys localized in thin shear bands is responsible for the weaker compositional dependence of both plasticity parameters,while dislocation gliding in crystalline materials is significantly more dependent on the exact structure,thus resulting in a larger scattering range.Based on the representative efficient cluster packing model,a set of composition-dependent atomic structural models is proposed to figure out the structure-property relationships of amorphous alloys in Pd-W-Si alloy system.

Theoretical prediction of high melting temperature for a Mo–Ru–Ta–W HCP multiprincipal element alloy

While rhenium is an ideal material for rapid thermal cycling applications under high temperatures,such as rocket engine nozzles,its high cost limits its widespread use and prompts an exploration of viable cost-effective substitutes.In prior work,we identified a promising pool of candidate substitute alloys consisting of Mo,Ru,Ta,and W.In this work we demonstrate,based on density functional theory melting temperature calculations,that one of the candidates,Mo_(0.292)Ru_(0.555)Ta_(0.031)W_(0.122),exhibits a high melting temperature(around 2626 K),thus supporting its use in high-temperature applications.