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.

Machine learning atomic dynamics to unfold the origin of plasticity in metallic glasses:From thermo-to acousto-plastic flow

Metallic glasses(MGs)have an amorphous atomic arrangement,but their structure and dynamics in the nanoscale are not homogeneous.Numerous studies have confirmed that the static and dynamic heterogeneities of MGs are vital for their deformation mechanism.The“defects”in MGs are envisaged to be structurally loosely packed and dynamically active to external stimuli.To date,no definite structure-property relationship has been established to identify liquid-like“defects”in MGs.In this paper,we proposed a machine-learned“defects”from atomic trajectories rather than static structural signatures.We analyzed the atomic motion behavior at different temperatures via a k-nearest neighbors machine learning model,and quantified the dynamics of individual atoms as the machine-learned temperature.Applying this new temperature-like parameter to MGs under stress-induced flow,we can recognize which atoms respond like“liquids”to the applied loads.The evolution of liquid-like regions reveals the dynamic origin of plasticity(thermo-and acousto-plasticity)of MGs and the correlation between stress-induced heterogeneity and local environment around atoms,providing new insights into thermo-and acousto-plastic forming.

Metallic glasses and metallic glass nanostructures for functional electrocatalytic applications

This brief review reports the recent advancement of metallic glasses and metallic glass nanostructures for functional electrocatalytic applications. Metallic glasses(MGs) or amorphous metals result from quenching the melts at a high cooling rate(e.g.,10^(6)K/s), bypassing crystallization. Metallic glasses are devoid of long-range translational order, no defects like grain boundaries, and multiple elements included. Due to these unique structural features, MG s show distinct and valuable mechanical, physical and chemical properties and therefore were widely studied as a structural material for decades. Even though MGs were proposed for catalytic applications earlier, a comprehensive study or attempt to apply these materials successfully in electrocatalytic applications are few since the intrinsic surface area is comparably lesser. A rejuvenated interest among the research community for applying various novel strategies in catalytic applications of MGs is highlighted in the present review. Theoretical approaches using density functional theory(DFT) and high-throughput screening assisted with machine learning paradigm advances the discovery of new MGs, which demonstrated high potential for catalytic applications. We focus on the basic features and recent advances in the MGs for catalytic applications like electrocatalytic water splitting reactions like HER, OER, fuel cell reactions like ORR, alcohol oxidation reactions like MOR, EOR,and degradation of harmful organic dyes from the industrial effluents. The presently advancing strategies for enhancing the performance of these metallic glass electrocatalysts through nanostructuring and high-throughput screening are discussed. The unique atomic-scale structural mechanism of the metallic glasses, which can favor the development of high-performance electrocatalysts even comparable to currently available precious-metal-based catalysts, will be discussed. Finally, we also give future directions on designing novel and superior metallic glass-based advanced catalysts.

Orientation Dependence of the Micro-Pillar Compression Strength in an Electron Beam Melted Ti-6Al-4V Alloy

An α/β two-phase Ti-6Al-4V alloy was fabricated by electron beam melting to obtain a basketweave structure.The orientation dependence of the mechanical properties of Ti-6Al-4 V alloy was studied by micro-pillar compression and post-mortem transmission electron microscopy analysis.The results indicate that different grains have different mechanical responses,and the possible attributions were discussed.Besides the orientation effect,due to the limited volumes of micropillars,the size of the a phases,dispersion of the β phases,and the presence of the free dislocation path also affect the mechanical properties of the micropillars to a large extent.Although no direct link was discovered between the mechanical properties and the parent β orientations,this work provided a promising method to further study the anisotropic mechanical behavior in Ti-6Al-4V alloy.