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Background: Older adults' psychological health is a public health issue that cannot be ignored, especially when these psychological health problems and related factors change across different social backgrounds because of rapid changes in traditions and family structures and the epidemic responses after the outbreak of COVID-19 in China. The aim of our study is to determine the prevalence of anxiety and depression and their associated factors among community-dwelling older adults in China. Methods: A cross-sectional study was conducted from March to May 2021 with 1173 participants aged 65 years or above from three communities in Hunan Province, China who were selected using convenience sampling. A structured questionnaire including sociodemographic characteristics, clinical characteristics, the Social Support Rating Scale (SSRS), the 7-Item Generalized Anxiety Disorder scale (GAD-7), and the Patient Health Questionnaire-9 Item (PHQ-9) was used to collect relevant demographic and clinical data and to measure social support status, anxiety symptoms, and depressive symptoms, respectively. Bivariate analyses were conducted to explore the difference in anxiety and depression based on samples' different characteristics. The multivariable logistic regression analysis was performed to test for significant predictors of anxiety and depression. Results: The prevalence of anxiety and depression were 32.74% and 37.34%, respectively. Multivariable logistic regression analysis revealed that being female, being unemployed before retirement age, lacking physical activity, having physical pain, and having three or more comorbidities were significant predictors for anxiety. Subjective social support and support utilization were significant protective factors. Regarding depression, religion, lacking physical activity, having physical pain, having three or more comorbidities were found to be significant predictors. Support utilization was a significant protective factor. Conclusions: The study group showed a high prevalence of anxiety and depression. Gender, employment status, physical activity, physical pain, comorbidities, and social support were associated with psychological health problems of older adults. These findings suggest that governments should focus on the psychological health problems of older adults by raising community awareness of issues related to older adults' psychological health. They should also screen for anxiety and depression among high-risk groups and encourage individuals to seek supportive counseling. [ABSTRACT FROM AUTHOR]

A new casting method for processing copper alloy bonding wires was proposed. The microstructure evolution process of melt-extracted copper alloy wires was analyzed. The causes of the formation of non-uniform microstructures were analyzed. [Display omitted] Copper alloy wires are regarded as essential for bonding in semiconductor packaging. However, the existing single-crystal copper wires are susceptible to oxidize, resulting in connection failure. And the current production process of multi-pass cold-drawing is complicated. In this study, nickel-aluminum-bronze (NAB) alloy wires by the melt-extracted method were investigated to avoid the problems mentioned above. The results showed that the microstructure of the copper alloy wire differs depending on the region. The nano-Ni 3 Al phase precipitates on the lath martensitic β' phase in the concave area, while the interior of the copper alloy wires contains a large number of reflection-twin of the β' phase. As the melt-extracted process continues, the cooling speed increases until the formation of the stable lamellar α w + β' structure. These results will shed new light on the formation mechanism of copper alloy bonding wires. [ABSTRACT FROM AUTHOR]

The micrometer scale sac-like alveoli are the most important and essential unit for gas exchange in the lung. Thus, design and fabrication of scaffolds for alveoli regeneration by tissue engineering approach should meet a few topography and functional requests such as large surface area, flexibility, and high gas permeability to their native counterpart. Testing the gas permeability of scaffolds through a fast and simple technique is also highly demanded to assist new scaffold development. This study fabricated alveolus-like scaffolds with regular pore shape, high pore connectivity, and high porosity produced by inverse opal technique alongside randomly distrusted porous scaffolds by salt leaching technique from two different materials (polyurethane and poly(L-lactic acid)). The scaffold surface was modified by immobilization of VEGF. A facile and new technique based on the bubble meter principle enabling to measure the gas permeability of porous scaffolds conveniently has been developed specifically. The cellular response of the scaffolds was assessed by culturing with bone marrow mesenchymal stem cells and coculturing with lung epithelial NL20 and endothelial HUVECs. Our results showed that the newly designed gas permeability device provided rapid, nondestructive, reproducible, and accurate assessment of gas permeability of different scaffolds. The porous polyurethane scaffolds made by inverse opal method had much better gas permeability than other scaffolds used in this study. The cellular work indicated that with VEGF surface modification, polyurethane inverse opal scaffolds induced alveolus-like tissues and have promising application in lung tissue engineering. [ABSTRACT FROM AUTHOR]

A novel type of bi-constituent wire composite was obtained by combining melt-extracted Gd 50 Al 30 Co 20 and Gd 55 Al 20 Co 25 microwire components with Curie temperature ( T C ) of 86 K and 110 K, respectively. For a field change of 5 T, the wire composite possesses a table-like feature spanning a temperature interval of 30 K with value of ∼8.6 J kg −1  K −1 , and enhanced refrigerant capacity (RC) and relative cooling power (RCP) values of ∼680 J kg −1 and ∼863 J kg −1 , respectively. The experimental results agree well with those calculated by a simple bi-composition model, demonstrating the possibility of designing wire-based composites with desirable magnetocaloric effects (MCE) for active magnetic refrigeration. [ABSTRACT FROM AUTHOR]

We report enhancements of both Curie temperature and magnetic refrigerant capacity in Gd 50 (Co 69.25 Fe 4.25 Si 13 B 13.5 ) 50 microwires, which were fabricated by the melt-extraction method. For a field change of 5 T, the maximum magnetic entropy change (−Δ S M max ), the refrigerant capacity (RC) and relative cooling power (RCP) reached high values of 6.56 J kg −1 K −1 , 625 J kg −1 and 826 J kg −1 , respectively. While the RC is similar to those of our previously reported GdAlCo microwires, a much broader working temperature range of ∼126 K and a higher Curie temperature of 170 K make the Gd 50 (Co 69.25 Fe 4.25 Si 13 B 13.5 ) 50 microwires more attractive for active magnetic refrigeration. [ABSTRACT FROM AUTHOR]

High-quality Gd60Co15Al25 microwires with an average diameter of 40 µm were successfully fabricated by the melt-extraction method. The as-cast microwires undergo a second-order paramagnetic to ferromagnetic (PM-FM) transition at ∼100 K. Large values of the magnetic entropy change (−Δ SM ∼9.73 J kg−1 K−1) and the refrigerant capacity (RC ∼732 J kg−1) are achieved for a field change of 5 T. A careful analysis of critical exponents near the PM-FM transition indicates the significant effects of structural disorder on the long-range ferromagnetic interaction and the magnetocaloric response of the microwires. The excellent magnetocaloric properties make the Gd60Co15Al25 microwires very promising for use in magnetic refrigerators operating in the liquid nitrogen temperature range. [ABSTRACT FROM AUTHOR]

Herein, we report high magnetocaloric performance of melt-extracted metallic glass Gd 60 Al 20 Co 20 microwires, which exhibit a large and reversible magnetocaloric effect (MCE). The isothermal magnetic entropy change (−Δ S m ) reaches as high as 10.1 J kg −1 K −1 and the refrigerant capacity (RC) has a large value of 681 J kg −1 for a field change of 5 T. The as-obtained Gd-based metallic glass microwires hold a great promise for multifunctional applications in MCE-based refrigeration of liquid nitrogen temperature range. [ABSTRACT FROM AUTHOR]

Highlights: [•] High-quality Gd55Al25Co20 metallic glass magnetocalorific fibers were melt-extracted. [•] They show superior MCE performance versus its counterpart in BMGs. [•] They have tensile strength of 1189MPa and high security threshold of 796MPa. [•] The excellent performances result from size effect and amorphous structure. [Copyright &y& Elsevier]

We report here on a comprehensive study of an alternatingcurrent Joule annealing (ACJA) method for optimizing the giant magnetoimpedance (GMI) effect of Co-rich amorphous wires for sensor applications. Experimental results indicated that the proper ACJA treatment can drastically improve the GMI property of as-cast wire. At 10 MHz, the maximum GMI ratio [ΔZ/Z0]max of ACJA-ed wire increase to 205.38%, which is nearly 3.3 times that of 62.84% for as-cast wire, and the maxima field response sensitivity ξmax of ACJA-ed wire increases to 345.90%/Oe by more than twice that of 170.92%/Oe for as-cast wire. With an increase of AC amplitude, a remarkable dependence of GMI performance appears on the microstructural evolution such as the structural relaxation, the degree of local order, as well as circular magnetic domains. Importantly, the atomic order orientation incorporating HRTEM observation and circumferential permeability were effectively increased by the co-action of thermal activation energy and magnetic field energy during ACJA, further to enhance the magnetic properties to some extent. Based on both the numerical calculation of transient temperature rise and GMI behavior, we propose ACJA as an efficient annealing technique to achieve simultaneous best performance of [ΔZ/Z0]max and ξmax for potentially magnetic sensor applications in detecting weak magnetic fields. [ABSTRACT FROM AUTHOR]

In this work, we report a comprehensive investigation on mechanical and giant magneto-impedance (GMI) properties of melt-extracted Co-rich amorphous microwires with the nominal composition of Co69.25Fe4.25Si13B13.5-xNbx (x=0, 1, 2, 3, 4). Results show that the tensile strength and GMI properties gradually increase with the substitution of B by Nb at first, and then decrease with a further Nb substitution. The meltextracted microwires with the substitution of B by 3% Nb exhibit a maximum tensile strength σm of 4000±50 MPa owing to the formation of nanosized crystals in the amorphous matrix. In addition, the substitution of B by 1% Nb assures an excellent GMI property. At 5 MHz, the maximum GMI ratio [ΔZ/Zmax]max for the melt-extracted microwires reaches as high as 450±10% versus 380±10% for traditional CoFeSiB microwires and the field-response sensitivity increases from 350±10% Oe-1 to 700±10% Oe-1 for 1% Nb substitution. It is thus concluded that both mechanical and GMI properties of the melt-extracted Co-based amorphous microwires can be greatly improved by properly adding Nb, and this is promising for many engineering applications, including high-resolution magnetic, stress and biomedical sensors. [ABSTRACT FROM AUTHOR]

Magnetic skyrmions offer promising prospects for constructing future energy-efficient and high-density information technology, leading to extensive explorations of new skyrmionic materials recently. The topological Hall effect has been widely adopted as a distinctive marker of skyrmion emergence. Alternately, here we propose a novel signature of skyrmion state by quantitatively investigating the magnetoresistance (MR) induced by skyrmionic bubbles in CeMn2Ge2. An intriguing finding was revealed: the anomalous MR measured at different temperatures can be normalized into a single curve, regardless of sample thickness. This behavior can be accurately reproduced by the recent chiral spin textures MR model. Further analysis of the MR anomaly allowed us to quantitatively examine the effective magnetic fields of various scattering channels. Remarkably, the analyses, combined with the Lorentz transmission electron microscopy results, indicate that the in-plane scattering channel with triplet exchange interactions predominantly governs the magnetotransport in the Bloch-type skyrmionic bubble state. Our results not only provide insights into the quantum correction on MR induced by skyrmionic bubble phase, but also present an electrical probing method for studying chiral spin texture formation, evolution, and their topological properties, which opens up exciting possibilities for identifying new skyrmionic materials and advancing the methodology for studying chiral spin textures. [ABSTRACT FROM AUTHOR]

• The novel medium-entropy alloys were fabricated by melt-extraction and exhibit excellent magnetic entropy change. • The microwires show typical amorphous characteristics and second-order phase transition. • The microstructure of microwires near room temperature is studied by in-situ HEXRD. A melt-extracted HoErCo medium-entropy alloy (MEA) with large magnetic entropy change and excellent magnetic refrigerant capacity is successfully designed in this study. The microstructure evolution of these microwires near room temperature is studied by an in-situ high energy synchrotron X-ray diffraction (HEXRD). The wires show typical amorphous characteristics during room temperature to 250 K. For a field change of 5 T, the maximum magnetic entropy change (-Δ S M max) of the microwires reaches a maximum value of 15.0 J•kg−1 K−1. Magnetization measurements revealed a paramagnetic to ferromagnetic phase transition at T C ~16 K. The refrigerant capacity (RC) and relative cooling power (RCP) are 527 J•kg−1 and 600 J•kg−1, respectively. This investigation highlights the potential of HoErCo MEA microwires as promising magnetocaloric effect materials for cryogenic applications of magnetic cooling. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEA) represent potentially disruptive materials across multiple industries, especially for refrigeration technologies. Building metal components layer-by-layer increases design freedom and manufacturing flexibility, thereby enabling high magnetic thermal properties of the multicomponent alloy. However, excessive alloying elements could limit the mass production potential, while prolonging the time to market. Here we demonstrate that a high performance magnetocaloric material can be synthesized from only three elements, HoErFe, by taking advantage of the combination of rare earth and transition elements. Novel medium-entropy alloys (MEA) are prepared by melt-extraction and exhibit excellent magnetocaloric properties. The amorphous/nanocrystalline structure of the microwires, which is confirmed by both transmission electron microscopy (TEM) and X-ray diffraction (XRD), gives the primary contribution to the MCE. The microwires undergo a ferromagnetic-paramagnetic (FM-PM) transition near the Curie temperature (T C = ~44 K), and a spin-glass (SG) behavior could be observed below the T C. The maximum magnetic entropy (-ΔS M max) was 9.5 J kg−1 K−1 under a field change of 5 T. Meanwhile, the refrigerant capacity (RC) and the relative cooling power (RCP) of the alloy microwires were 450 J·kg−1and 588 J kg−1, respectively. The high refrigeration efficiency and high magnetocaloric effect that is reversible make these novel metallic microwires attractive working materials for low-temperature magnetic refrigeration applications. • The novel medium-entropy alloys are prepared by melt-extraction and exhibit excellent magnetocaloric properties. • The wire composite shows a spin-glass behavior below Curie temperature. • The amorphous/nanocrystalline structure of the microwires exhibit enhanced magnetocaloric effect. [ABSTRACT FROM AUTHOR]

We report upon the excellent magnetocaloric effect in melt-extracted DyHoCo medium entropy microwires. The magnetic entropy change (-Δ S M) reaches a large value of ∼11.2 J kg−1 K−1 for a field change (μ 0 Δ H) of 5 T. The large value of -Δ S M is resulted from the large magnetic moments of Dy and Ho. In addition, the DyHoCo microwires show a good cooling efficiency; RC1, RC2 and RC3 are evaluated to be ∼530 J kg−1, ∼417 J kg−1 and ∼279 J kg−1, respectively, at μ 0 Δ H = 5 T. The DyHoCo microwires undergo a second-order paramagnetic-ferromagnetic transition at the Curie temperature of ∼35 K. The excellent magnetocaloric property makes the melt-extracted DyHoCo microwires a promising refrigerant for cryogenic cooling application. Image 1 • Dy 33.3 Ho 33.3 Co 33.4 medium entropy microwires were fabricated by melt-extraction. • DyHoCo microwires possess an amorphous structure and SOMT. • DyHoCo microwires show the excellent MCE performance. [ABSTRACT FROM AUTHOR]

• High entropy Gd 19 Tb 19 Er 18 Fe 19 Al 25 microwires were fabricated by melt-extraction. • Gd 19 Tb 19 Er 18 Fe 19 Al 25 microwires show amorphous structure and SOMT. • Gd 19 Tb 19 Er 18 Fe 19 Al 25 microwires show broaden working temperature range. In this paper, the magnetocaloric effect (MCE) of a high-entropy Gd 19 Tb 19 Er 18 Fe 19 Al 25 amorphous microwires fabricated by melt-extracted method are investigated systematically. These microwires exhibit a second-order phase transition from ferromagnetic to paramagnetic states at the Curie temperature of 97 K. The zero-field-cooling (ZFC) and field-cooling (FC) magnetization curves are irreversible when the temperature lower than the Curie temperature due to the spin glassy freezing behavior. The peak magnetic entropy change (Δ S M pk ) for a field change from 0 to 5 T reaches ~5.94 J/kg∙K. In accordance to two criteria refrigerant capacity, the values of refrigerant capacity (RC) and relative cooling power (RCP) reach ~569 J/kg and ~733 J/kg at a field change of 5 T, respectively. These results suggest that the melt-extracted Gd 19 Tb 19 Er 18 Fe 19 Al 25 microwires exhibit good MCE and have great potential to use as one kind of high temperature magnetic refrigeration material. [ABSTRACT FROM AUTHOR]

A new magnetocaloric composite composed of three types of soft ferromagnetic Gd‐based microwires with equal mass ratio and close magnetocaloric performances is designed. The Curie temperatures (TC) of these three wires are ≈97, ≈100, and ≈101 K, respectively. However, the magnetization versus temperature curve of the composite sample shows almost a single ferromagnetic–paramagnetic transition at ≈97 K. For a field change of µ0ΔH = 5 T, the maximum entropy change (−ΔSMmax) and refrigerant capacity (RC) of this composite are calculated to be ≈9.98 J kg−1 K−1 and ≈665 J kg−1, respectively. There is a good agreement between the calculated −ΔSM (T) curve and the experimental data, indicating weak magnetic interactions among different wire compositions. Additionally, the calculated universal master curves of the composite and its Gd‐Al‐Co components are fitted very well, which reveals the second‐order type of the magnetic transition for the composite. The designed composite integrates all magnetocaloric properties of its components, suggesting that the Gd‐based amorphous wires with close magnetocaloric properties can be designed as an excellent refrigerant for use in active magnetic refrigerators. [ABSTRACT FROM AUTHOR]

Induction skull melting (ISM) technology could melt metals with avoiding contamination from crucible. A long-standing problem of ISM is that the low charge energy utilization and inhomogeneous fields have obstructed its application in many critical metal materials and manufacturing processes. The present work investigated the problem through the structure optimization strategy and established a numerical electromagnetic-field model to evaluate components' eddy current loss. Based on the model, the effect of crucible and inductor structure on charge energy utilization, etc. was studied. Furtherly, the charge energy utilization was increased from 27.1 to 45.89% by adjusting the system structure. Moreover, structure modifications are proposed for enhancing electromagnetic intensity and uniformity, charge soft contact and uniform heating. The work constructed a basis for framing new solutions to the problem through ISM device structure optimization. [ABSTRACT FROM AUTHOR]

Recent studies have found that emotion dysregulation, negative affect, and metacognitions about online gaming are risk factors for Internet gaming disorder (IGD). However, few studies investigated the mechanisms underlying these interactions. The present study aimed to explore the relationships between emotion dysregulation and IGD, and the mediating effects of negative affect and metacognitions about online gaming. An online survey was conducted with young people (aged 10–24 years) who played video games. 1768 participants were included in this study. Observed variables, including emotion dysregulation, IGD, depression, anxiety, and metacognitions, were measured with self-report scales. Structural equation modeling (SEM) was used to analyze the relationships among the variables. The results showed that emotion dysregulation positively predicted IGD through a fully mediated model which included the independent mediating effects of negative affect and metacognitions about online gaming and their sequential mediating effect. The model explained 76.1 % of the variance in IGD. This was a cross-sectional study which could not infer causality. This study emphasizes that negative affect and metacognitions about online gaming mediate the effect of emotion dysregulation on IGD; moreover, metacognition may be a proximal factor of IGD. Thus, improving emotional regulation and modifying maladaptive metacognitions in young people may improve the prevention and treatment of IGD. • Emotion dysregulation positively predicts IGD. • Negative affect and metacognitions mediate the effect of emotion dysregulation on IGD. • Metacognitions about online gaming may be a proximal factor of IGD. [ABSTRACT FROM AUTHOR]

Ni50Mn25Ga20Fe5 ferromagnetic shape memory alloy microwires with diameters of ∼ 30–50 μm and grain sizes of ∼ 2–5 μm were prepared by melt-extraction technique. A step-wise chemical ordering annealing was carried out to improve the superelasticity strain and recovery ratio which were hampered by the internal stress, compositional inhomogeneity, and high-density defects in the as-extracted Ni50Mn25Ga20Fe5 microwires. The annealed microwires exhibited enhanced atomic ordering degree, narrow thermal hysteresis, and high saturation magnetization under a low magnetic field. As a result, the annealed microwire showed decreased superelastic critical stress, improved reversibility, and a high superelastic strain (1.9%) with a large recovery ratio (> 96%). This kind of filamentous material with superior superelastic effects may be promising materials for minor-devices. [ABSTRACT FROM AUTHOR]

The images on the inside back cover refer to the article by Dawei Xing et al. (pp. 1905–1910). They show the critical behavior for melt‐extracted Gd‐based microwires. The authors investigated Gd60Co15Al25 wires with an average diameter of 40 μm that underwent a second‐order paramagnetic to ferromagnetic (PM–FM) transition at ∼100 K. A careful analysis of critical exponents near the PM–FM transition was performed. The n value (related to the magnetic state of the specimen) of the investigated wires is ∼0.743 calculated from the magnetic field dependence of the maximum magnetic entropy change (ΔSm), which deviates from the value of n = 2/3 (∼0.67) based on the mean field approach. The critical exponents of β, γ, and δ for the present wires are obtained by the modified Arrott plots (MAP) method based on the scaling theory and the values are 0.432, 1.244, and 3.351, respectively. All these values also significantly deviate from those obtained according to the mean field theory (β = ∼0.5, y = ∼1, and δ = ∼3). Scaling plots obtained by using the critical exponents and the experimental data demonstrate that the critical exponents obtained for the present microwires are precise and reliable. This study indicates that the Gd60Co15Al25 microwires are excellent magnetic refrigerants for active magnetic refrigeration in the liquid nitrogen temperature range. [ABSTRACT FROM AUTHOR]

The discovery of giant magnetoelectric effect in Fe2Mo3O8 has sparked considerable interest in investigating the novel effects of M2Mo3O8 (M = Zn, Mn, Fe, Co, Ni) family, in particular the emergent physics driven by the M‐site ions. Herein, the structural evolution due to M‐site mixing is studied in the compound FeCoMo3O8 whose unit cell volume and lattice constant are slightly tuned compared with those of Fe2Mo3O8 and Co2Mo3O8. However, significant structure distortion occurs on the octahedron and tetrahedron as a result of the relaxation of the unbalanced force, caused by the distinction of the M ion radius in the mixing case. The octahedron and tetrahedron are shifted toward each other along the c‐axis which increases the coplanarity of the Fe and Co ions. The octahedron is compressed along the D3d‐symmetry axis and its bonds are elongated significantly. A complex tension‐like distortion is induced for the tetrahedron. Its bond along the C3v‐symmetry axis is elongated and other three bonds are shortened. The study demonstrates that ions mixing at the M sites would introduce intrigue structure modulation in the M2Mo3O8 family, which would tune the electronic orbit structure. This may shed new light on understanding the emergent behaviors of the material family. [ABSTRACT FROM AUTHOR]

Impedance output stability of Co-rich amorphous wires depends largely on the wire-terminal-connection, which can be accomplished by composite electroplating towards a robust sensor application. The present experimental results indicated that Ni/Cu composite layer composed of Ni, Cu plating and passivating treatment show a homogeneous microstructure, and excellent surface wettability, weldability and thermal expansion coefficient matching under variable temperature of wire-terminal-connecting. The properties of composite electroplated layer are mainly influenced by cathode current density, electroplating time and electrolyte temperature. The inhomogeneous distributed clustering-regions, disproportionated reaction, tendency of hydrogen brittleness and crack have been reduced by optimized coactions of intermolecular Van der Waals force, inner diffusion and mechanical bonding of electroplated layer. Therefore, the wire-terminal-connection is able to effectively improve impedance output stability by minimizing the disturbance of stray capacity, decreasing radio-frequency wave emission and electromagnetic signal attenuation, and suppressing the destabilization or concussion. [ABSTRACT FROM AUTHOR]

• Life's Essential 8 (LE8) is an updated tool for the assessment of cardiovascular health (CVH). • Better CVH evaluated by LE8 was associated with decreased depression prevalence among US adults. • Nicotine exposure and sleep health were identified as two major contributors to this negative relationship. Few studies have examined the association of Life's Essential 8 (LE8) with depression among US adults. This is a cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) 2011–2020. LE8 score was measured as the mean score of eight metrics (diet, physical activity, nicotine exposure, sleep health, body mass index, blood lipid, blood glucose, and blood pressure). CVH was categorized into low, moderate, and high according to tertiles of LE8 score. Depression was defined based on the 9-Item Patient Health Questionnaire (PHQ-9). Weighted logistic regressions were conducted to assess the associations of depression with CVH. Compared with participants with low CVH, the fully adjusted ORs of depression were 0.45 (0.37, 0.55) in the moderate CVH and 0.21 (0.15, 0.30) in the high CVH participants, respectively. The results remained robust in subgroup and sensitivity analyses. All eight LE8 metrics were negatively associated with depression, while nicotine exposure and sleep health were identified as two major metrics contributing to the association. Better CVH evaluated by LE8 was associated with decreased depression prevalence among US adults. Adherence to a higher CVH score, especially targeting smoking cessation and proper sleep duration, might be beneficial for prevention of depression. [ABSTRACT FROM AUTHOR]

In this study, a new strategy was utilized to fabricate Mg-based hydrogen storage fibers with uniform elemental distribution and diameters of 30–50 μm. The in-situ formation of nano-precipitates in Mg 85 Ni 14.8 Ag 0.2 metallic glass fibers was visually observed at varied annealing temperatures. It indicates the metastable Mg 6 Ni phase is formed from an amorphous microstructure initially. Then, the needle-like Mg 2 Ni nanoparticles precipitate at 140–160 °C and subsequently grow into spherical shapes. This results in the formation of the fiber structure with well-distributed nano-Mg 2 Ni particles. The alloy fibers can absorb H 2 at only 40 °C, and the activation energy for hydrogenation is lowed to be 46.9 kJ/mol. The onset desorption temperature of hydride is reduced to 220 °C due to the improved the catalytic efficiency by uniformly distributed Mg 2 Ni nanoparticles. The abundant interfaces, as well as the shortened distance by micropores, serve as paths for the fast diffusion of H atoms. A strategy for fabricating efficient Mg 2 Ni nano-catalysts in a novel Mg-Ni-Ag fiber and its enhanced hydrogen storage properties. [Display omitted] [ABSTRACT FROM AUTHOR]

• The solidification process under different mold temperatures was studied. • The duration of the supercooled liquid state was significantly improved as the mold temperature increased. • Increasing the mold temperature improved the solidification time without altering the amorphous solidification behavior. To explore the relationship between mold temperature and the formation of large-size metallic glasses, the influence of mold temperature on the solidification process and microstructure evolution of amorphous melts was investigated. It was found that increasing the mold temperature to 623 K contributes to improving the solidification time from ∼1.79 s to ∼2.32 s without affecting the solidification behavior of amorphous melt. However, the duration of the supercooled liquid state was prolonged by the excessively high mold temperature, resulting in a considerable increase in the glass transition time from ∼12.78 s to ∼145.7 s and a decline in the cooling rate from 27.6 K/s to 2.1 K/s, which ultimately leads to the crystallization of the sample. In addition, it has been observed that the 573 K mold temperature is not only the optimal mold temperature to ensure the amorphous nature of the sample but is also beneficial to improve the internal temperature gradient of the sample, thereby reducing the risk of deformation or cracking. Appropriate control of mold temperature can provide valuable guidance for large-size amorphous castings and associated process parameters. [ABSTRACT FROM AUTHOR]

High-purity melting is critical for casting metallic glass components, which would be achieved by developing the induction skull melting (ISM) technology used in casting process. The melting process of metallic glass components during ISM is urgently desired to be understood, which is rare so far. Based on this, a full-scale coupling simulation model for ISM technology with finite element method (FEM) was proposed, which contains all physical fields engaged in the melting processes. Furthermore, the metallic glass melting process was experimentally and numerically investigated based on the full-scale coupling model. The distribution of the multi-physics field within the charge was elaborated based on the numerical simulation results, especially electromagnetic field contribution, heat transfer, meniscus shape and melt reflux zone. Furthermore, due to its high viscosity, a long holding time to improve melt homogeneity is necessary for metallic glass melt. The chief aim of this work is to understand of induction melting process for melting amorphous master alloys using induction skull melting technology and to provide a foundation for the casting method to form bulk metallic glasses. [ABSTRACT FROM AUTHOR]

Herein, fluid oil joule annealing modulation (FOJA) for improving the giant magnetoimpedance (GMI) property of CoFe‐based microwires with the microstructure is adopted, and magnetic domain structure is systematically investigated. Compared with general joule annealing (JA) method, a much larger DC current can be used. The maximum GMI value is 440.8% in the 250 mA FOJA‐treated sample and the maximum monotonically increasing magnetic field is 12 Oe in 400 mA FOJA‐treated sample. In the 100–400 mA FOJA‐treated samples, there is a nearly linear increase and decrease relationship between GMI and the magnetic field. In addition, the FOJA method can control the radial stress release and helical magnetic domains of the microwire by changing the Joule heat transfer and the circumferential magnetic field and then tune the GMI performance of the microwires. The remarkable features, including a continuous and clear linear‐sensitive response field Hex of 0–95 Oe, quick response sensitivity, large GMI ratio, and excellent tunability, make the FOJA‐tailored microwires promising candidate material for miniaturized GMI sensors. [ABSTRACT FROM AUTHOR]

In this work, the dislocation etching pit morphology and etching kinetics on the A‐{112¯0} plane of sapphire crystal (α‐Al2O3) are studied experimentally. The results show that the etch pit exhibits a subrhombic 3D morphology, which is consistent with the atom arrangement symmetry of the A plane. Further analysis shows that the two adjacent sides of the rhombic etch pits correspond to the directions [33¯01¯] and [33¯02], respectively; both of them are in the atomic close‐packing direction of A plane. The etch pits are controlled by a chemical reaction between Al2O3 and potassium hydroxide (KOH) with the reaction activation energy of 51.7 kJ mol−1, which is developed in a manner of kinematic wave by the step moving with a constant speed. [ABSTRACT FROM AUTHOR]

• reveal the etching behavior and kinetics of cavity on c-plane of crystalline sapphire. • observed unexpected regular shape of etched cavity with 15 faceted planes. • revealed the Arrhenius type etching kinetics of cavity, demonstrating the step flow etching mechanism working there. Techniques to fabricate patterned sapphire substrates (PSSs) have attracted much attention in recent decades. Wet etching behaviors and crystalline sapphire processes are critical for PSSs applications to improve the performance of light-emitting diodes. This study investigated the shape evolution behaviors and associated kinetics of cavities on the c-{0001} plane in crystalline sapphire during wet etching. It was revealed that wet etching reduces the cavity aspect ratio, and the cavity shape is a complicated structure constructed by 15 faceted planes of c-{0001}, r-{1 1 ¯ 02}, p-{11 2 ¯ 3}, m-{10 1 ¯ 0}, and s-{1 1 ¯ 01} families. A constant etching rate was demonstrated, suggesting the step flow mechanism of etching. The etching activation energy of crystalline sapphire is reduced by preformation of cavities as elucidated by the Arrhenius kinetic model followed during the etching process. This study provides new insight into wet etching behaviors of crystalline sapphire and might open up a way for fabricating sapphire substrate with large aspect ratio patterns. Image, graphical abstract [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel hydrogen storage alloy fiber is prepared by the method of melt extraction. • Well-dispersed Mg 2 Ni nanoparticles precipitated in Mg-Ni-Ag fiber as a catalyst. • The hydrogen absorption capacity of Mg 85 Ni 14.8 Ag 0.2 fiber reaches 1.5 wt% at 50 °C. • Hydrogen transport is further promoted by micro-pores and cracks formed in fiber. The intermetallic compound Mg 2 Ni shows improved hydrogen de-/absorption kinetics and a lower desorption temperature compared to pure Mg. However, the coarse Mg 2 Ni phase and its limited hydrogenation capacity restrict the application of the Mg 2 Ni alloy. In this study, an attempt was made to prepare Mg-Ni alloy fibers with a higher Mg content and a well-distributed Mg 2 Ni catalytic phase using the melt extraction (ME) method, and a unique metallic glass fiber was formed. With pre-annealing at 350 °C in a vacuum, uniformly dispersed Mg 2 Ni nanoparticles are in-situ formed, the phase transition is revealed to be metallic glass → Mg 6 Ni → Mg 2 Ni + Mg. About 1.5 wt% of hydrogen can be absorbed by the Mg-Ni fibers at 50 °C, and it is completely released in 8.8 min at 225 °C. Both the JMA and Kissinger models were utilized to accurately characterize the dehydrogenation activation energy, and the values of 90.4 and 95.8 kJ/mol were obtained, respectively. The hydrogen desorption process involves two distinct processes, the decomposition of Mg 2 NiH 4 nanoparticles and MgH 2 hydride in sequence, with dehydrogenation enthalpy changes of 64.5 and 78.2 kJ/mol, respectively. After hydrogen absorption and desorption cycles, a loose structure forms around the Mg 2 Ni nanoparticles. This structure serves as an efficient nucleation site for hydrides and provides diffusion paths for H atoms. [ABSTRACT FROM AUTHOR]

Bifilm defects have been proposed to be critical for the generation of various metallurgical defects in castings and have been reported to exist in various composition-based alloys. However, the geometry structure of bifilm defects has not yet been well understood. This present work reconstructed the bifilm defects in a nickel-aluminium bronze alloy casting in three-dimensional (3D) space through the use of computer tomography technology. It was shown that the shape of the bifilm defects is very complex and different from a spherical defect in 3D space. The bifilm defects were experimentally extracted successfully by an electrolysis method and were imaged, which confirmed the folded double-layer structure of the bifilm defects. These results will shed new light on the understanding of bifilm defects and improve the defect control engineering of castings. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The microstructure and magnetic properties including magnetocaloric performance of as-prepared and heat-treated La(Fe,Ni) 11.5 Si 1.5 alloys were systematically investigated. The experimental results indicate that the as-prepared La(Fe,Ni) 11.5 Si 1.5 alloys are composed of α-Fe phase and LaFeSi phase, and the saturation magnetization M s can achieve 159.1 emu/g, as for the larger content of ferromagnetic α-Fe phase. The peritectic reaction occurs during vacuum annealing process, and the decrease of α-Fe phase content reduced the hysteresis loss, meanwhile the NaZn 13 -type structure (1:13 phase) generated. In particular, the magnetocaloric properties of La(Fe,Ni) 11.5 Si 1.5 alloys annealed at 1373 K are superior to that of annealed at 1323 K. And the magnetic entropy change (-Δ S m) of the alloys annealed at 1373 K is up to 20.87 J kg−1 K−1, while Refrigeration Capacity (RC) reaches 415.59 J kg−1 at a magnetic field of 5 T. From the perspective of solid-phase reaction dynamics, the increase of annealing temperature could beneficially accelerate the peritectic reaction process, and result in the increasing content of 1:13 phase, thereby enhancing their magnetocaloric characteristics. Therefore, the microstructure and magnetocaloric properties of La(Fe,Ni) 11.5 Si 1.5 alloys could be effectively modulated by optimizing the annealing process, and it also provides a significant technical reference for the practical application of room-temperature Magnetic Refrigeration (MR) technology. Magnetocaloric properties of La(Fe,Ni) 11.5 Si 1.5 alloys based on NaZn 13 -type structure are distinctly enhanced by modulation of vacuum annealing treatment and Ni-doping. Image 1 • Effects of impurity phases on the magnetic properties were studied in detail. • The saturation magnetization and hysteresis loss of as-prepared alloy are larger than them of heat-treated alloy. • The formation of La(Fe,Ni,Si) 13 (1:13) phase in the alloy is promoted by annealed at higher temperature. • Magnetocaloric properties of La(Fe,Ni) 11.5 Si 1.5 alloy can be effectively improved by rising annealing temperature. [ABSTRACT FROM AUTHOR]

Gd-based metallic microfibers have been the research highlights due to the significant magnetocaloric effect. Herein, the atomic cluster micro-regions are constructed in Gd-based microfibers to further improve the magnetocaloric effect. The results show that the continuous and amorphous microfibers with excellent softly magnetic and thermal stability properties are obtained. The maximum magnetic entropy change -Δ S m max of Gd-based microfibers increases first and then decreases with Ni alloying degree increase. Among which, the better magnetocaloric properties is obtained in (Gd 60 A 20 lCo 20) 95 Ni 5 microfibers. The maximum magnetic entropy change, refrigeration capacity (RC), and relative cooling power (RCP) at 5 T reach 11.57 J/kg K, 834.14 J/kg, and 1138.16 J/kg, respectively. The outstanding magnetocaloric properties of microfibers are attributed to the indirect interaction coupling caused by Ni elements and the atomic cluster micro-regions, which lead to a fundamental shift in magnetic entropy. The findings of this study promote the application of Gd-based microfibers in the field of magnetic refrigeration. • The excellent magnetocaloric properties are obtained in GdAlCoNi5 microfibers after Ni alloyed. • The -Δ S m max, RC and RCP of GdAlCoNi5 microfibers reach 11.57 J/kg·K, 834.14 J/kg and 1138.16 J/kg, respectively. • The atomic cluster micro-regions promote the transformation of magnetic entropy disorder to order after Ni alloyed. [ABSTRACT FROM AUTHOR]

In this study, the optimized fabrication and evolution of the microstructure and magnetic transition behavior of the melt-extraction LaFe 11.2 Si 1.8 microwires have been studied. After the optimization of extraction technique (heating power 22 KW, feeding rate 30–50 μm/s, rotation velocity 1700 r/min), the content of La(Fe,Si) 13 phase in the as-extracted microwires was 54 wt% due to the high solidification velocity, which was increased to 85 wt% via annealing at 1373 K for 20 min. The amount of La(Fe,Si) 13 phase was increased and the composition of La(Fe,Si) 13 phase became more homogenized through peritectic reaction and short-distance diffusion in the microwires during annealing process. The coexistence of the nanocrystalline and amorphous structures contributed to the broad magnetic transition temperature range of the as-extracted and annealed microwires. The annealed microwires exhibited a second-order magnetic transformation behavior and showed a maximum magnetic entropy change | ΔS M | max of 6.2 J/kg·K and working temperature interval of 36.0 K under a magnetic field of 20 kOe. Image 1 • LaFe 11.2 Si 1.8 microwires were prepared by melt-extraction technique. • The content of La(Fe,Si) 13 phase in the as-extracted microwire reached 54 wt%. • Nanoscale La(Fe,Si) 13 phase and α-Fe grains were formed in the extracted microwire. • 85 wt% La(Fe,Si) 13 phase was obtained in microwire annealed at 1373 K for 20 min. • The annealed microwire exhibited.| ΔS M | max 6.2 J/kg·K and ΔT FWHM 36.0 K under 20 kOe. [ABSTRACT FROM AUTHOR]

Abstract The atomic structure evolution of Gd 36 Tb 20 Co 20 Al 24 high entropy metallic glass microwire from room to cryogenic temperature has been studied by in-situ high energy synchrotron X-ray diffraction. During the cooling process, the atomic volume decreases. For short-range order, the coordination numbers of all atomic pairs increase. As the temperature decreases, bond lengths of large atom-small atom and small atom-small atom pairs keep decreasing whereas that of large atom-large atom pairs unexpectedly increases continuously. The mechanism of atomic structure evolution is proposed, which might be helpful for better understanding the low temperature magnetocaloric effect of high entropy metallic glasses. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Herein, the magnetocaloric effect (MCE) of Fe-doped Gd-rich microwires has been investigated. Experimental results indicated that this type of the microwires has entirely amorphous microstructure and smooth surface, and exhibits a relatively higher Curie temperature (∼121.8 K) as for the appropriate Fe substitution, and a remarkable and reversible MCE effect with almost no thermal or magnetic hysteresis loss. For a magnetic field change of 5 T, the isothermal magnetic entropy change (-Δ S m ) for the longitudinal direction reaches as large as 10.33 J kg −1 K −1 , besides the refrigerant capacity (RC) achieves a relatively large value of 748.22 J kg −1 . Meanwhile, the Arrott plots also indicate that the ferromagnetic-paramagnetic transition is of the second-order. Therefore, it can be concluded that the obtained Fe-doped Gd-rich wires are used as intelligent materials with enhanced MCE property for potential multifunctional applications in magnetic refrigeration field. [ABSTRACT FROM AUTHOR]

• Apparent liquid-liquid transition (LLT) of several Zr-Cu-Ni-Al melts have been discovered at about 300 K above the liquidus temperature. • Two different glasses are obtained by regulating LLT in these alloys, manifesting that LLT comes from the competition between two types of atomic clusters. • LLT reconstructs the atomic structure at short-range order which was seldom verified in previous work. Up to now, the research of liquid-liquid transition (LLT) has significantly improved the understanding of its liquid structure and evolution, which is crucial to addressing the longstanding problem with glass formation. However, it remains unclear how LLT affects the vitrification and structures of glasses, due to the challenge in experimentally exploring LLT in high-temperature melt well above the liquidus temperature. In the present study, an experiment is conducted to observe LLT in three Zr-Cu-Ni-Al melts at around 1450 K from both dynamic and thermodynamic perspectives. It is discovered that superheated fragility is closely associated with glass-forming ability. By controlling the melt temperature, two types of metallic glasses are obtained, showing difference in crystallization behaviors, which is attributed to the competition between crystal-like clusters and icosahedral-like clusters. Prior to the LLT, the formation of crystal-like clusters is dominant. Afterwards, the LLT promoted formation of icosahedral-like clusters becomes dominant. Due to the inherited signatures in glass, LLT is manifested by the changes in both medium-range order structure and short-range order structure. This study further reveals the pattern of microstructural evolution accompanied by LLT in high-temperature multi-component melts, which is conducive to the control on structure and properties of glasses from liquids. [ABSTRACT FROM AUTHOR]

We have proposed a series of novel tailoring techniques for integrating conventional vacuum annealing (CVA) and the specific (e.g. transverse- and rotated-) magnetic field annealing (as denoted by TMFA and RMFA respectively), and systematically investigated the impacts of them on the giant magnetoimpedance (GMI) properties and domain microstructure of Co-based amorphous wires. Experimental results indicated that a multiplex MFA treatment i.e, two-step CVA annealing under a rotated magnetic field of 4000Oe, can realize remarkable enhancement of GMI in comparison with the as-prepared, CVA-treated and MFA-treated wires. The GMI ratio increased firstly and then tended to be stable with increasing frequency, moreover, both permeability and GMI ratio decreased with the increase of DC magnetic field. At 13 MHz, the maximum GMI ratio [Δ Z / Z max ] max and field response sensitivity ξ max of RMFA-ed wires increased to 398.39% and 21.84%/Oe, respectively, which is 2.41 times and 3.17 times than those of 165.18% and 6.88%/Oe for the as-prepared wires. Essentially, the physical process of RMFA action is mainly described as the multi-angle induced magnetic anisotropy and atomic reordering dynamic process due to the co-action of rotatory variation magnetic field energy and thermal activation. Meanwhile, the GMI behavior of TMFA evolving from single peak (SP) to double peaks (DPs) is attributed to the increase of magnetic domain driving force (namely domain wall movement increment) and uni-directional inducing magnetic anisotropy at relatively high frequency, which modified the GMI ratio and field sensitivity to 334.61% and 33.51%/Oe, respectively. Therefore, it can be concluded that both RMFA & TMFA would be used to explore microwires with enhanced GMI property for high-performance sensor applications. [ABSTRACT FROM AUTHOR]

Herein, we reported the influences of accumulated direct current annealing (ADA) on the GMI properties and microstructures of Zr-doped melt-extracted (Co 68.15 Fe 4.35 Si 12.25 B 12.25 Zr 3 ) amorphous microwires. There indicated that ADA-ed wires enhanced GMI properties and improved the microstructures remarkably in comparison with as-fabricated wires. The maximum GMI ratio [Δ Z / Z 0 ] max and equivalent magnetic circumferential anisotropy field (EMCAF) of ADA-ed microwires were increased to 256.01% and 4 Oe at 20 MHz, respectively, which are more than nearly 8 and 2 times of 33.62% and 1.6 Oe for as-fabricated wires, respectively. Moreover, the maximum magnetic field response sensitivity ( ξ max ) increased to 372.57%/Oe, which is much higher than the as-fabricated wires of 44.71%/Oe. The remarkable enhancement of GMI performance was considered as the microstructural evolution including structural relaxation, appearance of nano-crystallization, and circumferential arrangement of surface magnetic domains. Nano-crystallization degree and circumferential magnetic domains arrangement were effectively improved by actions of Joule thermal energy and circular magnetic field generated ADA as shown in HRTEM and magnetic force microscope (MFM) analysis. Based on above, both the excellent GMI performances and relatively large ξ max values indicate the ADA is an effective annealing technique for thermal treating the melt-extracted amorphous wires which applied for potentially magnetic sensor in detecting low-intensity magnetic fields. [ABSTRACT FROM AUTHOR]

The effects of Fe doping on the microstructure, martensite transformation and superelasticity in melt-extracted Ni 50 Mn 25 Ga 25− x Fe x ( x =1–6) microwires were investigated. The unique solidification process during melt-extraction creates the micron-sized diameter wires with small grains and semicircular cross-section. At ambient temperature Ni 50 Mn 25 Ga 25− x Fe x ( x <4) microwires are austenite phases with a cubic L2 1 structure, while microwires with x >5 are martensitic phases with seven-layered modulated (7M) structure. The results point out that martensite transformation temperatures are strongly related to Fe content due to the change of valence electron concentration ( e / a ). Reversible superelastic strains of 0.92% and 0.75% are obtained in Ni 50 Mn 25 Ga 21 Fe 4 and Ni 50 Mn 25 Ga 20 Fe 5 microwires, respectively. It is demonstrated that the temperature dependence of stress-induced martensite (SIM) stress follows the Clausius–Clapeyron relation. The temperature dependence of SIM stress in Fe-doped Ni–Mn–Ga microwires is 10.5 MPa/K. [ABSTRACT FROM AUTHOR]

We present the torsional stress induced magnetoimpedance (MI) effect and surface domain structure evolution of magnetostrictive melt-extracted Co68.15Fe4.35Si12.25B13.25Nb1Cu1 microwires. Experimental results indicate that the surface domain structures observed by magnetic force microscope (MFM) transform from the weak circumferential domain of as-cast state to the helical domain under large torsional strain of 81.6 (2π rad/m). Domain wall movement distorts at torsional strain ξ=20.4 (2π rad/m) and forms a helical anisotropy with an angle of around 30° versus axial direction of wire. At 15 MHz, the maximum of GMI ratio ΔZ/Z(%) increases to 194.4% at ξ=20.4 (2π rad/m) from 116.3% of the as-cast state and then decreases to 134.9% at ξ=102.0 (2π rad/m). The torsion magnetoimpedance (TMI) ratio ΔZ/Zξ(%) is up to 290%. Based on this large torsional strain and high MI ratio, the microwire can be as an referred candidate for high-performance TMI sensor application. [ABSTRACT FROM AUTHOR]

Ni50Mn25Ga25- xFe x (1 ≤ x ≤ 6) microwires with a diameter of 30-50 µm were prepared by melt-extraction. The effects of Fe doping on the martensite transformation temperature, Curie point and magnetic properties before and after chemical ordering treatments were investigated. Experimental results show that Ni50Mn25Ga25- xFe x microwires exhibit typical thermoelastic martensite transformation and magnetic transition. Transformation temperatures of the microwires increase with Fe content with a rate of 27.3 K/at%. Thermal hysteresis during martensite transformation is lowered after Fe doping. The Curie point of Ni50Mn25Ga25- xFe x (1 ≤ x ≤ 6) microwires keeps stable at 390 K, which is 25 K higher compared with Ni2MnGa ternary alloy. After chemical ordering heat treatment, the microwires exhibit a typical ferromagnetic transition and a higher saturation magnetization at low field compared to as-extracted microwires. [ABSTRACT FROM AUTHOR]

We reported the magnetocaloric properties of Heusler-type Ni 48 Mn 26 Ga 19.5 Fe 6.5 microwires with diameter of ∼50 μm which were fabricated by a precise melt-extraction method. The Fe-doped Ni–Mn–Ga microwires after chemical ordering heat-treatment exhibit negligible thermal and magnetic hysteresis along the axial direction due to their small magnetocrystalline anisotropy and display excellent magnetocaloric effect (MCE) for both magnetic (paramagnetic–ferromagnetic) phase transition and structural (austenite–martensite) phase transition. The maximum entropy change (−Δ S m ), ∼4.7 J kg −1 K −1 , is obtained during the structural transition induced by an external magnetic field of 50 kOe at a temperature of ∼361 K. Moreover, tiny positive magnetic entropy also appears when the applied field is lower than 5 kOe. [ABSTRACT FROM AUTHOR]

We report a systematic study of a new class of melt-extracted Ni49.7Mn25.0Ga19.8Fe5.5 polycrystalline microwires in terms of fabrication, microstructural characterization, and evaluation of shape memory effects (SMEs). The as-extracted microwire has enhanced ductility due to its fine grains with diameters of 1-3 µm. The total strain in its martensite state reached 2.14% as loading at 350 MPa and 100% plastic deformation strain recovery was achieved after heating process. During thermo-cycling tests, a fully recoverable transformation strain of 1.5% was obtained under a tensile bias-stress of 468 MPa. It can be therefore concluded that Fe-doped microwires display the least strain dependence on stress compared with other alloys such as NiTi and NiMnGa, and could be useful in devices required constant stress output. [ABSTRACT FROM AUTHOR]

Bimetallic gradient alloys have attracted research attention recently due to their potential applications in the aerospace and automobile industries. In this study, Al-20Si/7075 bimetallic gradient alloys were successfully manufactured by co-spray forming and the roll process. We investigated the thermal expansion behavior of the gradient alloy. It was found that the coefficients of thermal expansion increased with silicon content and increased temperature, reaching the highest point at 573 K, after which they decreased on account of the relaxation of residual thermal stress and the silicon desolvation from the supersaturated aluminum phase. The measured thermal expansion coefficient can be roughly predicted through the traditional theoretical models. Our results revealed the thermal expansion behavior of Al-20Si/7075 bimetallic gradient alloys and would improve the development of new type aluminum–silicon alloy for electronic packaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanocrystalline Fe-containing GdTbCoAl high-entropy-metallic-glass were attained. • Curie temperature is tuned by Fe-doping in a wide temperature range of 81–108 K. • Magnetic entropy change 7.6–8.9 J kg−1 K−1 for 5 T were achieved. • The dual-phase structure with T C distribution enhances the cooling efficiency. Through designing the composition and processing approach, the non-equiatomic (Gd 36 Tb 20 Co 20 Al 24) 100-x Fe x (x = 0, 1, 2 and 3 at.%) high-entropy-metallic-glass (HE-MG) alloy microwires were successfully fabricated by melt-extraction technique. The microstructure and magnetocaloric properties of the microwires were systematically investigated. The microwires possess tunable Curie temperatures, i.e. 81–108 K, above the typical rare-earth (RE) containing HE-MG reports. The high Curie temperatures are attributed to the designed composition. Magnetocaloric response peak values of Fe-containing GdTbCoAl alloy microwires range 7.6–8.9 J kg−1 K−1 (5 T), which are comparable to those of many outstanding RE-containing magnetocaloric HE-MGs. The characteristics of the melt-extraction method, combining with compositional effects, favor the formation of amorphous and nanocrystalline phases. The increase in the cooling efficiency for microwires with higher Fe content can be attributed to the broadening of the Curie temperature distribution induced by the composition difference between nanocrystalline phase and amorphous matrix. The designed composition and the melt-extraction processing approach for Fe-containing GdTbCoAl alloys can tune their Curie temperatures towards a temperature range of natural gas liquefaction and improve their magnetocaloric properties. This demonstrates that Fe-containing GdTbCoAl HE-MG composite microwires have great potential as high-performance magnetic refrigerants. [ABSTRACT FROM AUTHOR]

The influence of surface microstructural regulation mechanisms on the mechanical and giant magneto-impedance (GMI) properties of as-cast melt-extracted CoFe-based wires has been systematically researched based on morphology, phase distribution and domain structure parameters. A series of statistical models were applied to analyze the mechanical properties and followed by mapping the curve of cumulative failure rate for wire application. It was found that the average and highest fracture strengths, average tensile strain increased with Cu substitution and reached peaks of ~3725 MPa, ~4250 MPa and ~2.7%, respectively. Verified structure-simulation experiments revealed that surface Rayleigh waves effectively split the main crack and the diffusely distributed nanocrystalline in surface area acted as a pinning point to impede the crack growth, enhancing the mechanical properties. The GMI ratio displayed similar variations and attained a maximum value of 700 ± 5% as well as the resistance and reactance ratios improved to ~687% and ~2206%, respectively. The enhanced relative dielectric permeability μ s resulting from the increased domain wall energy density and the decreased surface domain width. The unique synchronous enhancement of CoFe-based wires satisfies the demand for emerging magnetoelectric sensor applications, e.g. flexible and wearable sensors, equipment self-monitoring sensors, and array robotic skin sensors under harsh working environments. [Display omitted] • Surface microstructural design of melt-extracted CoFe-based amorphous wires were systematically researched. • The relationship between surface nanoscale Rayleigh waves and domain structure was established. • Enhanced mechanisms of mechanical and giant magneto-impedance (GMI) properties were clarified. • Highest fracture strengths and tensile strain enhanced to ~4250 MPa and ~2.7%, and GMI ratio improved to 700 ± 5%. [ABSTRACT FROM AUTHOR]

• The oxide bifilm defects were separated from the casting matrix through electrolysis method for the first time. • The composition, phase structure and morphology of individual bifilm defects were measured directly. • The mechanical properties of amorphous alumina bifilm were tested. • The formation reasons of bifilm with different crystal types were analyzed. Bifilm defects are proposed to be critical among the metallurgical defects generated in castings. However, direct investigations of individual bifilm defects separated from the casting matrix were absent to date. In this study, separated bifilm defects in nickel-aluminium bronze were investigated systematically. The results showed that an electrolysis method can successfully separate the bifilms from the casting matrix. Al 2 O 3 with an amorphous state, a γ-phase structure, and an α-phase structure were observed in the separated bifilms, respectively, violating the conventional prediction of only α-Al 2 O 3 existing in the final casting. The thickness of the bifilm defects was not uniform and varied in a wide range from several nanometres to several hundred nanometres. Upon analysis, the thinner bifilm presented a much smaller Young's modulus in comparison to the crystallised Al 2 O 3. The thicker bifilm was intergrown with several single crystals and covered by smooth and faceted faces. These results suggest the complex bifilms form in cast nickel-aluminium bronze alloys and more investigations are therefore required in future. [ABSTRACT FROM AUTHOR]

Herein, the influence of annealing current intensities on magnetic properties of Gd-based microfibers was systematically investigated. The experimental results indicated that the as-prepared microfibers have amorphous structure and excellent thermal-stability, and the Curie temperature T C of which slightly change before and after annealing. The general magnetic physical magnitudes (M s , M r , μ 0 H c and μ m) of microfibers increase firstly and then decrease with the rising of annealing current intensities, and those of the microfibers annealed at 90 mA microfibers are more obvious (M s = 255 A m2/kg and μ m = 0.38 ± 0.01). Similarly, the magnetocaloric parameters of microfibers also increase firstly and then decrease with the rising of current intensities. At 5 T of magnetic field change μ 0 Δ H , the maximum magnetic entropy change Δ S m max and refrigerant capacity RC of 90 mA annealed metallic microfibers are 12.77 J/(kg·K) and 906 J/kg, respectively, and which remarkably increased in compared with the as-prepared state, respectively. From the microstructural evolution perspective, a certain intensity current annealing induces the tendency of micro-regional clusters and nanocrystals, forming atomic ordered regions, and the internal residual stress release with a reduction of magnetic anisotropy. Meanwhile, the magnetic ordering and the critical magnetic-moment rotational driving-force were changed after Fe-doping, resulting in effective improvement of refrigerant capacity. Accordingly, the current-annealed Gd-Al-Co-Fe microfibers can be adopted as low-temperature magnetic refrigeration working-medium, which also provides a theoretical foundation for magnetic refrigeration technology application. Magnetocaloric properties of Gd-Al-Co-Fe metallic microfibers current-annealed at 90 mA are significantly improved according to the microstructural evolution and magnetic ordering modulation. Image 1 • Effects of current annealing intensities on the magnetic properties were investigated in detail. • MCE characteristics of Gd-Al-Co-Fe microfibers could be obviously improved at 90 mA. • Magnetocaloric mechanism is illustrated by the perspective of structural evolution and magnetic ordering transformation. [ABSTRACT FROM AUTHOR]

• Reveal the etching behavior and kinetic of cavities on the A-plane of sapphire crystal which was unclear before. • Unexpectedly, the depth of cavity is stable during the etching process. • Propose and demonstrate the potential application of cavity etching as a preparation method to achieve PSSs. Chemical wet etching technology is widely applied in semiconductor device fabrication such as the patterned sapphire substrates. However, the etching of pre-formed structure is still lack of investigations, which has potential applications in the preparation of particular devices. By using molten KOH etchant, the present work studied the wet etching behaviors of cavity on the A-plane of sapphire crystal in three-dimensional space and revealed the etching kinetics. It was demonstrated that the cavity will evolve into a complicate symmetric shape with multiple facet planes during etching. The width of the cavity is gradually expanded however the depth of the cavity is stable during etching, where the Arrhenius model was held, indicating that the etching process is realized by step flow removal of atoms. The present results improve the understanding of the morphology evolution and relevant kinetics of a pre-formed structure on sapphire crystal during wet etching, which shed further light on the single crystal wet etching technology for device fabrication. [ABSTRACT FROM AUTHOR]