It is not easy to fabricate materials that exhibit their theoretical 'ideal' strength. Most methods of producing stronger materials are based on controlling defects to impede the motion of dislocations, but such methods have their limitations. For example, industrial single-phase nanocrystalline alloys and single-phase metallic glasses can be very strong, but they typically soften at relatively low strains (less than two per cent) because of, respectively, the reverse Hall-Petch effect and shear-band formation. Here we describe an approach that combines the strengthening benefits of nanocrystallinity with those of amorphization to produce a dual-phase material that exhibits near-ideal strength at room temperature and without sample size effects. Our magnesium-alloy system consists of nanocrystalline cores embedded in amorphous glassy shells, and the strength of the resulting dual-phase material is a near-ideal 3.3 gigapascals-making this the strongest magnesium-alloy thin film yet achieved. We propose a mechanism, supported by constitutive modelling, in which the crystalline phase (consisting of almost-dislocation-free grains of around six nanometres in diameter) blocks the propagation of localized shear bands when under strain; moreover, within any shear bands that do appear, embedded crystalline grains divide and rotate, contributing to hardening and countering the softening effect of the shear band.
as a particularly promising and appealing technology because it has the potential to be both environmentally friendly and low cost. [2] This application creates demand for non-noble-metal-based electrocatalysts to substitute for the currently used highcost Pt catalysts; however, the development remains extremely challenging.High-entropy materials (HEMs) with unique microstructures and unprecedented physicochemical and mechanical properties have attracted a great deal of research interest in many different applied research fields. [3,4] High-entropy alloys (HEAs), as a prominent and already wellestablished group of HEMs, are generally defined as containing five or more principal components alloyed into a crystalline solid-solution phase with unexpected stability and chemical complexity. Many HEAs have demonstrated superior properties relative to traditional alloys, including unprecedented fracture toughness at cryogenic temperatures, [5] ultra-high mechanical performance overcoming the trade-off between strength and ductility, [6] and excellent catalytic selectivity and activities. [7] Largely because of their proximal arrangement of Electrochemical water splitting offers an attractive approach for hydrogen production. However, the lack of high-performance cost-effective electrocatalyst severely hinders its applications. Here, a multinary highentropy intermetallic (HEI) that possesses an unusual periodically ordered structure containing multiple non-noble elements is reported, which can serve as a highly efficient electrocatalyst for hydrogen evolution. This HEI exhibits excellent activities in alkalinity with an overpotential of 88.2 mV at a current density of 10 mA cm −2 and a Tafel slope of 40.1 mV dec −1 , which are comparable to those of noble catalysts. Theoretical calculations reveal that the chemical complexity and surprising atomic configurations provide a strong synergistic function to alter the electronic structure. Furthermore, the unique L1 2 -type ordered structure enables a specific site-isolation effect to further stabilize the H 2 O/H* adsorption/desorption, which dramatically optimizes the energy barrier of hydrogen evolution. Such an HEI strategy uncovers a new paradigm to develop novel electrocatalyst with superior reaction activities.As society seeks to drastically reduce the future usage of fossil fuels, molecular hydrogen is widely recognized as one of the most sustainable and regenerative alternative energy resources. [1] When considering the wide range of hydrogen production methods, electrochemical water splitting has been identifiedThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.
Developing highly efficient and durable electrocatalysts for hydrogen evolution reaction (HER) under both alkaline and acidic media is crucial for the future development of a hydrogen economy. However, state-of-the-art high-performance electrocatalysts recently developed are based on carbon carriers mediated by binding noble elements and their complicated processing methods are a major impediment to commercialization. Here, inspired by the high-entropy alloy concept with its inherent multinary nature and using a glassy alloy design with its chemical homogeneity and tunability, we present a scalable strategy to alloy five equiatomic elements, PdPtCuNiP, into a high-entropy metallic glass (HEMG) for HER in both alkaline and acidic conditions. Surface dealloying of the HEMG creates a nanosponge-like architecture with nanopores and embedded nanocrystals that provides abundant active sites to achieve outstanding HER activity. The obtained overpotentials at a current density of 10 mA cm −2 are 32 and 62 mV in 1.0 m KOH and 0.5 m H 2 SO 4 solutions, respectively, outperforming most currently available electrocatalysts. Density functional theory reveals that a lattice distortion and the chemical complexity of the nanocrystals lead to a strong synergistic effect on the electronic structure that further stabilizes hydrogen proton adsorption/desorption. This HEMG strategy establishes a new paradigm for designing compositionally complex alloys for electrochemical reactions.
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