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It remains challenging to develop low-cost body-centered cubic (BCC) high-entropy alloys (HEAs) with superior mechanical properties. In this work, we investigated the microstructure and mechanical properties of BCC FexCrNiAl0.5Ti0.5 HEAs containing L21 nanocrystals. With increasing the Fe content from Fe2 to Fe4 and Fe6, the formation of a big blocky L21 phase and a σ phase can be fully suppressed, and the size and fraction of the L21 crystals also decrease. Fe4 and Fe6 HEAs exhibit an optimized dual-phase microstructure with high-density L21 nanocrystals homogeneously distributed in the BCC matrix. Fe4 and Fe6 HEAs show high strength and do not fracture even at a large compressive strain of 70%, exhibiting the best combination of strength and fracture strain among all the reported BCC HEAs with nanocrystals. The superior mechanical properties of Fe4 and Fe6 HEAs are attributed to the optimized microstructure. These findings promote the development of low-cost HEAs with superior mechanical properties. [ABSTRACT FROM AUTHOR]

A high-entropy alloy Fe10Co10Ni10Cr10Mn60 ribbon catalyst with a face-centered cubic structure was designed by using Co and Ni as the main catalytic elements and combining various co-catalytic elements, such as Fe, Mn, and Cr. Substantial element selective corrosion occurs during the acid solution corrosion process, which induces the exposure of many Co and Ni atoms, increases the specific surface area, and further results in the formation of many vacancies and dislocations. This unique structure generates a positive electron effect, that is the peaks of Ni2p3/2 and Co2p3/2 shift to lower binding energies, namely, approximately 1 eV for Ni and 0.8 eV for Co, indicating the Co and Ni enrich electrons. The catalyst shows an excellent catalytic performance for the hydrolysis of NaBH4 after corrosion for 90 s, whose hydrogen production rate approaches 18.46 l/(m2·min). This work opens up a direction for the application of the macroscopic scale high-entropy alloy in the catalytic hydrogen field. [ABSTRACT FROM AUTHOR]

We studied the thermodynamics and kinetics of a non-equiatomic Ti 32.8 Zr 30.2 Ni 5.3 Cu 9 Be 22.7 high entropy metallic glass (HEMG, ΔS config. ∼1.44R) with a critical size for glass formation over 50 mm. The characteristic transition temperature, enthalpy of transition and specific heat capacity along with the relaxation time at different heating rate were determined using differential scanning calorimeter (DSC) measurements. It reveals that the present HEMG supercooled liquid shows the lowest thermodynamic driving force against the nucleation and growth of crystalline phases with comparing to other typical MG formers. Meanwhile, it exhibits the ultrastrong behavior near glass transition in terms of the Angell's fragility concept. The alloy has a fragility index of D* = 45.2, higher than all the typical MG formers reported so far. Both thermodynamic and kinetic factors are responsible for the ultrahigh glass-forming ability of the HEMG alloys. [ABSTRACT FROM AUTHOR]

The influence of casting temperatures on microstructures and mechanical properties of rapidly solidified Cu50Zr45.5Ti2.5Y2 alloy was investigated. With increasing casting temperatures, the amount of the crystalline phase decreases. At a high casting temperature, i.e., 1723 K, glass-forming ability (GFA) of the present alloy is enhanced. The results imply that adjusting the casting temperature could be used for designing the microstructures of bulk metallic glass matrix composite. Nanoindentation tests indicated that CuZr phases are slightly softer and can accommodate more plastic deformation than the amorphous matrix. Compression tests confirmed that this kind of second phase (CuZr) precipitated under lower casting temperatures helps to initiate multiple shear bands, resulting in a great improvement in mechanical properties of the samples. Our work indicates that casting temperatures have a great influence on GFA, microstructures, and mechanical properties of the rapidly solidified alloy, therefore controlling the casting temperature is crucial to the production of BMGs. [ABSTRACT FROM AUTHOR]

This study focuses on the preparation of Mo0.5VNbTiCr0.25 refractory high-entropy alloy (RHEA) coatings on the surface of Zr-4 alloy using laser cladding technology. The coated samples underwent 24-h aging heat treatment at temperatures of 600 °C, 800 °C, and 1000 °C, as well as laser remelting. The crystal structure, microstructure, microhardness, and wear resistance of each RHEA coating sample were comprehensively analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscattering diffraction (EBSD), Vickers hardness test, and general-purpose friction and wear test. The different effects of aging heat treatment and laser remelting treatment on the microstructure and properties of Mo0.5VNbTiCr0.25 RHEA coatings were investigated. The results showed that each group of RHEA coating samples had good metallurgical bonding with the substrate without obvious defects such as pores and cracks. The coated samples were mainly composed of body-centered cubic (BCC) phases and a small amount of hexagonal close-packed (HCP) phases. The mechanical properties of the laser remelted samples were the best, with a microhardness value of 526 HV0.2, and the best wear resistance. The wear mechanisms included adhesive wear, oxidative wear, and creep wear. [ABSTRACT FROM AUTHOR]

The amorphous catalysts can be electrochemically activated to expose active sites during the short-range order structure, greatly increasing the number of active sites and thus significantly improving the water oxidation activity. Herein, we developed disordered sandwich-like multi-layer structure with abundant oxygen vacancies as a highly excellent electrocatalyst for the oxygen evolution reaction (OER), which was derived from amorphous Ni 40 Fe 40 B 20 ribbons precursors through in situ hydroxylation and electro-oxidation in alkaline solution. The as-fabricated product shows the low overpotential of 249 mV and 338 mV at a current of 10 mA·cm−2 and 250 mA·cm−2 with a Tafel slope of 43 mV·dec−1, respectively. This excellent catalytic performance is attributed to the synergistic effect resulted from the hybrid composition of disordered α-Ni(OH) 2 and γ-FeOOH, excellent electron/mass transfer due to the presence of abundant oxygen vacancies and expandable actual surface area. Moreover, the catalysts after structural reconstruction still maintain good flexibility, which is good for industrial applications. This work may provide insight into the combination of disordered structure and oxygen vacancies through in situ grown on amorphous alloys and make them as promising industrial OER electrocatalysts. Unlabelled Image [ABSTRACT FROM AUTHOR]

• Cu-based MGs as electrodes for dye degradation exhibit high catalytic performance. • The degradation efficiency is 96% within 40 min using Cu 55 Zr 45 MG electrodes. • The Cu 55 Zr 45 MG electrodes can degrade the dye solution with different pH values. • Electrochemical action tends to the generation of the active substances. Metallic glasses have received a lot of attention on wastewater treatment due to their unique atomic structure, and the use of metallic glasses as electrodes has produced unexpected electrocatalytic degradation effects for many pollutants through combining with electrochemical technology. However, it still is a formidable challenge to find a metallic glass electrode material with both efficient and clean for the catalytic degradation of pollutants. In this work, the Cu 55 Zr 45 metallic glassy ribbons are used as an electrode to degrade azo dyes and show the excellent degradation effect, which can reach 95.6% within 40 min. In the degradation process, almost no additives are produced and Cu 55 Zr 45 metallic glassy ribbons have excellent effects under different pH conditions. Meanwhile, it exhibits good stability for degradation efficiency during the 8 cycle degradation tests of the amorphous alloy electrode. When the copper nanoparticles are exposed on the surface of the ribbons, the oxidized copper obtained synergistically produce activated radicals is the primary degradation mechanism, where the auxiliary degradation mechanisms include electron transfer and the promotion of active chlorine. This research develops a new type of electrode material for wastewater treatment, and the economy and high efficiency of Cu 55 Zr 45 metallic glass endow it the expandable functional applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Discovering new catalytic applications of Fe-based metallic glasses (MGs) besides the decolorization of azo dyes is an active topic. In this article, two types of coke wastewater before anaerobic treatment (I) and after aerobic treatment (II) are applied to investigate the catalytic performance of Fe 78 Si 8 B 14 and Fe 73.5 Nb 3 Cu 1 Si 13.5 B 9 MGs in Fenton-like system. The experimental parameters, including hydrogen peroxide concentration, temperature and solution pH are detailed studied. The Fe 78 Si 8 B 14 MGs exhibit a superior catalytic capability in wastewater treatment compared with the Fe 73.5 Nb 3 Cu 1 Si 13.5 B 9 MGs. The Fe 73.5 Nb 3 Cu 1 Si 13.5 B 9 MGs provide less reactive sites and lower Fe content in the coke wastewater due to the inclusion of Nb, restricting the generation of hydroxyl radicals and hindering the degradation reaction. The chemical oxygen demand removal efficiency of the wastewater I and II treated with Fe 78 Si 8 B 14 MGs could achieve 71% within 30 min and 89% within 60 min under the optimal condition, respectively. These results expand the practical applications of Fe-based MGs in treating environmental pollutants. • Fe-based metallic glasses are firstly applied to treat coke wastewater. • High chemical oxygen demand removal efficiency could be achieved by the Fe 78 Si 8 B 14 metallic glasses with low dosage of H 2 O 2. • Inclusion of Nb restricts the degradation reaction of the Fe 73.5 Nb 3 Cu 1 Si 13.5 B 9 metallic glasses. [ABSTRACT FROM AUTHOR]

Addition of a small amount of La and Co enhances the stabilization of supercooled liquid and glass-forming ability (GFA) of an Al 85 Ni 7 Er 8 metallic glass. The Al 85 Ni 5 Co 2 Er 6 La 2 alloy exhibits large supercooled liquid region of 40 K, high GFA with a critical thickness of 450 μm, and the viscosities on the order of 10 7 −10 9 Pa s in the supercooled liquid state. The Al-based glassy nano-scale patterns were formed by imprinting, indicating its good thermoplastic formability. The possible mechanism for the improvement of the supercooled liquid stability of the Al Ni Er alloy by addition of La and Co elements was discussed in terms of the crystallization behavior. [ABSTRACT FROM AUTHOR]