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• A flexible-annealing technique has been invented, which can achieve fast heating rate and uniform temperature distribution. • The (Fe 0.8 Co 0.2) 85 Si 2 B 12 Cu 0.8 Mo 0.2 nanocrystalline alloy exhibits high B s up to 1.88 T, low coercivity of 6.3 A/m, as well as good plasticity. • The excellent properties are attributed to the controllable construction of diluted amorphous-nanocrystalline structure caused by flexible-annealing. The traditional high-temperature annealing process is difficult to control the morphology and size of the crystallization phases in amorphous alloy systems with high ferromagnetic element content, leading to mechanical brittleness and soft magnetic properties deterioration. Here, we developed a flexible-annealing technique and successfully achieved a fine nanocrystalline structure in a high-ferromagnetic-content system of (Fe 0.8 Co 0.2) 85 Si 2 B 12 Cu 0.8 Mo 0.2. It is exciting that the (Fe 0.8 Co 0.2) 85 Si 2 B 12 Cu 0.8 Mo 0.2 nanocrystalline alloy exhibits high B s up to 1.88 T, low coercivity of 6.3 A m–1, as well as good plasticity. The excellent comprehensive properties are attributed to the controllable construction of diluted amorphous-nanocrystalline structure, the rapid release of internal stress, and the suppression of relaxation-induced uniformity achieved by the flexible annealing process. The results provide a fast and new paradigm for the development of next-generation high- B s soft magnetic materials. [Display omitted] [ABSTRACT FROM AUTHOR]

• In-situ bulk metallic glass composites (BMGCs) with excellent ductility and work hardening were successfully developed using a low vacuum high pressure die casting (LV-HPDC) technology along with industrial grade raw materials. • The LV-HPDC method shows a smaller volume fraction difference of the dendrite phase for BMGCs with the same composition, although the size of the β-phase is generally larger compared to the copper mold suction casting method. • The ductility of the BMGCs prepared by LV-HPDC can be maintained if two conditions are met: (1) the volume fraction of β phase stays below 62% ± 2%, and (2) the appearance of the dendritic phase satisfies a size uniformity. The glass-forming ability and mechanical properties of metallic glasses and their composites are well known to be sensitive to the preparation conditions and are highly deteriorated by industrial preparing conditions such as low-purity raw materials and low vacuum. Here, we showed that a series of in-situ bulk metallic glass composites (BMGCs) which exhibit excellent ductility and segmental work hardening were successfully developed utilizing a high vacuum high-pressure die casting (HV-HPDC) technology along with industrial-grade raw materials. The tensile properties of these BMGCs are systematically investigated and correlated with the alloy microstructure. As compared with the copper mold suction casting method, the volume fraction difference of the dendrite phase for the BMGCs with the same composition is not significant when fabricated by the HV-HPDC, whereas the size of the β-phase is generally larger. In-situ BMGCs with the composition of Ti 48 Zr 20 (V 12/17 Cu 5/17) 19 Be 13 obtained by the HV-HPDC process show ductility up to 11.3% under tension at room temperature and exhibit a certain amount of work hardening. Two conditions need to be met to enable the BMGCs, which are prepared by vacuum die-casting to retain favorable ductility: (1) The volume fraction of β phase stays below 62% ± 2%; (2) The equiaxed crystals with a more uniform size in the range of 5–10 μm. Meanwhile, the results of the present study provided guidance for developing BMGCs with good ductile properties under industrial conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

Development of high-performance catalysts with facile, self-supporting, simple and noble-metal-free features for hydrogen and oxygen evolution reactions (HER and OER) is a long-lasting pursuit. Herein, a facile self-oxidized Ni nano-foam with self-supporting nanoporosity is obtained by single-step dealloying of Mg80Ni20metallic glass ribbons. The Ni nano-foam exhibits superior HER performance with an overpotential of 33.1 and 71.4 mV at the current density of 10 and 100 mA cm−2, and low OER overpotential of 330 mV at 10 mA cm−2. Outstanding long-term stability up to 100 h is confirmed for both HER and OER. A water electrolyzer based on the Ni nano-foam couple shows good stability and remarkable activity for overall water splitting, which requires 1.58 V to reach 10 mA cm−2. The geometry features of the Ni nano-foam, i.e., three-dimensional structure, ultrafine size, high porosity and large surface area are highly beneficial for catalytic activity. The synergic effect of the Ni/NiO composite at the ligament skin is confirmed to decrease the free energy for hydrogen binding, facilitate the H−OH bond breaking and accelerate OH−ion formation, which significantly improves the intrinsic HER activity. The outstanding HER and OER performances of the self-oxidized Ni nano-foam validate the metal nano-foams as promising catalyst candidates, especially in view of the ultrafine nanoporous, self-supporting, composition regulation, single-step synthesis and massive fabrication features.

We introduce a non-equiatomic Fe61Mn18Si11Cr10medium entropy alloy designed by subjecting it to transformation-induced plasticity upon deformation at room temperature. Microstructure characterization carried out using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and X-ray diffraction (XRD) shows a homogeneous solid solution FCC + BCC structured dual phase. Investigations on the deformation substructures at specific strain levels via EBSD reveal the deformation-induced transformations of γ→ α′ and γ→ ɛ. The strengths, particularly yield strength, of the designed alloy are found to be higher than these of the well-studied five component FeMnNiCoCr system for the introduction of the hard phase (α′-martensite). When tensile tests are performed at different strain rates of 10–4s−1, 10–3s−1, 10–2s−1, the tested material exhibits a slightly negative strain rate sensitivity and work hardening rate sensitivity.

In order to obtain high photocatalytic performance, co-catalysts loading is most commonly used, which has economic disadvantages and can cause environmental pollution. Here, we combine the strategy of controllable thickness of CdS with hydrogen binding properties and hydrogen adsorption free energy (ΔGH). An ultrathin (1.5–2.5 nm) (002) faceted CdS nanobelt was synthesized by a stirring-assisted solvothermal method. Without any co-catalysts, it achieved a superior high visible-light photocatalytic performance of 282.12 mmol g−1h−1and an apparent quantum yield of 82.4% at 420 nm. This super photocatalytic performance arises from the exposed (002) facets and the controllable thickness of the CdS nanobelt, where the controllable thickness of the CdS nanobelt leads to a desirable value for the hydrogen adsorption free energy (ΔGH) resulting in higher photocatalytic performance. This work provides a facile strategy that can contribute to exploiting the high efficiency co-catalysts-free photocatalyst for photocatalytic hydrogen production.

Photoluminescent polymers with merely nonaromatic chromophores have attracted rapidly growing attention owing to their importance in the significant fundamental, encryption, and anticounterfeiting fields. Based on the clustering-triggered emission mechanism, through-space conjugation and conformational rigidification of nonaromatic chromophores are crucial to photoluminescence, which are also dependent on molecular arrangement. Herein, polyamide-6 (PA-6) with well-defined molecular arrangements was thus studied. The luminescence from the PA-6 solution is enhanced upon aggregation from solution to amorphous solid and further boosted with the formation of highly regular molecular arrangement. More importantly, both blue and green fluorescence from PA-6/formic acid (FA) solutions were observed because of the variable clusters formed among PA-6 and FA. To make clear of this, PA-6 cast film (PCF) and PA-6 electrospun film (PEF) were prepared and belonged to α- (antiparallel molecular arrangement) and γ (parallel molecular arrangement)-form crystals, as confirmed by Fourier transform infrared, X-ray diffraction, and Raman measurements. The relationship between molecular arrangement and luminescence of PA-6 molecules was clarified by their photophysical properties in solids and solutions. Notably, color-tunable cryogenic phosphorescence of PA-6 solids was also detected. Such aggregation-enhanced emission and tunable phosphorescence of PA-6 solids are ascribed to the formation of diversified amide clusters together with remarkably rigidified molecular conformations owing to the highly regular molecular arrangement in the aggregated states.

A novel approach of improving the antibacterial rate by tailoring matrix texture was investigated in 2.0 wt%Cu-bearing Fe-17Cr alloy through different rolling processes. Demonstrated by X-ray diffraction (XRD), the main orientation relationship between the copper precipitation and matrix is Kurdjumov–Sachs (K–S) relationship of {111}Cu//{110}Fe, <110>Cu//<111>Fe. Because of being elongated along <111>Matrixdirections, the rod-shaped copper precipitation in the matrix grain with {110} crystal plane is parallel to the rolling plane and has a maximum area exposed to the outside environment. The crystallographic orientations in the hot-rolled sample are equally distributed and there is no very focused and intense orientation. However, there are very strong components on the γ-fiber ({111}⊥ND texture) and Goss texture in the cold-rolled sample. Thus, the effective exposed area of copper precipitation in the cold-rolled sample is larger than that in the hot-rolled sample. Because the strong γ-fiber is beneficial to improve the corrosion resistance property, the cold-rolled sample has a better corrosion resistance and the copper ions are more easily released from the cold-rolled sample compared with the hot-rolled sample. Hence, the γ-fiber ({111}⊥ND texture) and Goss texture can improve the antibacterial rate obviously.

Abstract

Two rapidly solidified (RS) Mg ribbons with the compositions of Mg97Zn2Gd1and Mg90Zn5Gd5(at.%) were first prepared by the planar flow casting method. These RS ribbons were subsequently consolidated by spark plasma sintering (SPS). The use of SPS on the RS ribbons was demonstrated to be an effective processing route to control W-phase precipitation process while keeping fine grains. The size of W-phase particles was less than 200 nm in Mg97Zn2Gd1alloy and smaller than 500 nm in Mg90Zn5Gd5alloy. The content of W phase was approximately 34 vol% and 41 vol% in the two SPS bulks, respectively. The compressive properties showed that the yield compressive stress (YCS) and ultimate compressive stress of the Mg97Zn2Gd1alloy reached 200 MPa and 390 MPa, respectively, and an elongation of 0.24. The corresponding values for the Mg90Zn5Gd5alloy were 313 MPa, 504 MPa, and 0.14, respectively. Based on the results of the quantitative analysis, W-phase nanoparticles with size less than 100 nm exhibited obviously strengthening effect in the Mg alloys. It highlighted that the W-phase nanoparticles contributed a large proportion of the YCS in the Mg97Zn2Gd1alloy and a relatively small proportion for that of the Mg90Zn5Gd5alloy.

Bimodal microstructures with primary a-phase volume fractions ranging from 14.3% to 57.1% were gained in Ti-6Al-4V (Ti-64) alloy through annealed in two-phase region at various temperatures below the b-transus point. Then the influence of the primary a-phase volume fraction on the mechanical properties of Ti-64 were studied. The results show that, at room temperature and a strain rate of 10[?]3 s[?]1, the yield stress decreases but the fracture strain augments with added primary a-phase volume fraction. The equiaxed primary a-phase possesses stronger ability to coordinate plastic deformation, leading to the improvement of the ductile as well as degradation of the strength of Ti-64 with higher primary a-phase volume fraction. As the temperature goes up to 473 K, the quasi-static yield stress and ultimate strength decrease first and then increase with the incremental primary a-phase volume fraction, due to the interaction between the work hardening and the softening caused by the DRX and the growth of the primary a-phase. At room temperature and a strain rate of 3x103 s[?]1, the varying pattern of strength with the primary a-phase volume fraction resembles that at a quasi-static strain rate. However, the flow stress significantly increases but the strain-hardening rate decreases compared to those at quasi-static strain rate due to the competition between the strain rate hardening and the thermal softening during dynamic compression process.

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