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This paper systematically studies the changes in the microstructure and magnetic properties of CoFeSiBNb series metallic fibers before and after AC annealing. The influence of current intensity on the magneto-impedance (MI) effect of the fibers is analyzed and the mechanism of current annealing to improve the MI characteristics is further revealed. The results show that the surface of the CoFeSiBNb metallic fibers before and after AC annealing is smooth and continuous, the tensile strength of CoFeSiBNb3 fiber is 5.15 GPa and it is the most stable and fracture-reliable. After AC annealing, metallic fibers' general magnetic properties and MI ratio increase at first with current intensity and then decrease at higher intensities. Specifically, the 140 mA AC annealed metallic fiber shows excellent magnetic properties with Ms, μm, Hc, and Mr values reaching 94.38 emu/g, 0.4326, 34.36 Oe, and 13.94 emu/g, respectively. With an excitation frequency of f = 1 MHz, the fiber's [ΔZ/Zmax]max, ξmax, Hk, and Hp reached 216.81%, 31.04 %/Oe, 1 Oe, and 2 Oe, respectively. During the current annealing process, Joule heat eliminates residual stresses in the fibers while forming atomically ordered micro-domains, which improves the degree of its organizational order. Meanwhile, a stable toroidal magnetic field is generated, which promotes the distribution of the magnetic domain structure of the fibers, thereby improving the MI effect.

Refractory high-entropy alloys (RHEAs) have a great potential in high-temperature electronics, extensive aerospace and biomedical applications due to their unique strength and ductility. Herein, the effects of alloying elements on the mechanical and electronic properties of NbTaTiZrX (X = V, Mo, Hf, W and Re) RHEAs are investigated by using the density functional theory (DFT) in combination with the special quasi-random structure (SQS) and virtual crystal approximation (VCA) methods. The calculated results show that alloying of Mo, W and Re with high elastic modulus can enhance the strength and the hardness of RHEAs. Among them, NbTaTiZrRe RHEA with the best strengthening effect has a yield strength of exceeds 2 GPa, which is notably higher than other considered high-entropy alloys. For alloying of V and Hf, the ductility of RHEAs is improved, and among which, NbTaTiZrHf RHEA has a relatively best ductility. Compared with other NbTaTiZrX RHEAs, spiral dislocations in NbTaTiZrHf RHEA are more prone to nucleate, and which confirms its excellent ductility. Moreover, the reduction of pseudo energy gaps and the formation of Hf–Hf strong metallic bonds further confirm its metallic ductility from the electronic density of states and charge density. The theoretical predictions in this study are congruent with the existing experimental data, and have certain theoretical guidance relevance for enhancing the mechanical characteristics of NbTaTiZrX (X = V, Mo, Hf, W and Re) RHEAs.

In this paper, the microstructure and mechanical properties of CoCrFeNiMox (x = 0, 0.1, 0.3, 0.5, 0.7, and 1.0) high-entropy alloys (HEAs) prepared with high-vacuum arc melting method were studied in detail. After Mo-doping, the strengthening mechanism of HEAs mainly included the component segregation strengthening and the second phase strengthening. Cr and Mo elements were enriched at the grain boundary of HEAs, which leaded to the formation of σ phase and strengthens the alloys. The microhardness and strength increased with Mo contents, while the elongation decreased gradually. Among which, the higher microhardness, yield strength, and ultimate tensile strength of CoCrFeNiMo0.3 alloy reach 205.96 HV, 292.22 MPa, and 593.25 MPa, respectively, in compared with other alloys. More importantly, the percentage elongation of which remains 37.36%, and the microhardness distribution was uniform with an average value of 7.4 GPa and an elastic modulus of 263.6 GPa. The research findings presented in this paper could serve as a valuable theoretical basis and practical foundations for the strengthening efforts of face centered cubic (FCC) HEAs.

In order to reduce the deformation resistance, the rolling process of metastable β titanium alloys is generally carried out in the β single-phase state, which causes the problem of non-uniform grain size during the subsequent annealing process, thus affecting the alloy properties. Here we first solution-treated the as-cast Ti–15Mo–3Al-2.7Nb-0.2Si alloy at 740 °C to obtain α + β phase, then cold rolled it with a reduction of 60 %, and finally annealed it at 710–810 °C for 2–240min. Characterization of the annealed metastable β alloy revealed that α phase was involved in the rolling deformation at the same time and recrystallized on the β matrix during the subsequent annealing process, known as equiaxial dispersion, which impeded the recrystallization of the β grains, and ultimately an ultrafine crystalline microstructure of α + β phases with an average grain size of less than 2 μm was obtained.

In this paper, vacuum annealing has been adopted to introduce atomic cluster micro-regions inside Gd-based metallic microfibers to further explore the effect of the structural changes on the magnetocaloric properties and the mechanism which is systematically expressed. The experimental results indicate that the as-prepared Gd-based metallic microfibers have favorable amorphous formation ability and thermal stability. After annealing @ 380 °C, the maximum magnetic entropy change −ΔSmmax, refrigerating capacity (RC), and relative cooling power (RCP) values of the Gd-based metallic microfibers are 7.20 J/kg·K, 459.4 J/kg, and 588.7 J/kg, respectively. Combined with the transmission electron microscopy analysis results, the internal organizational order of the annealed microfibers is significantly altered, and the atomic clusters formed in localized regions, which reduce the magnetocrystalline anisotropy of the microfibers. While under the uni-action of an external magnetic field, the magnetic moment rotation state and magnetic domain structure distribution of the micro-region atoms will be changed obviously, thereby changing the general magnetic properties and magnetocaloric properties of the metallic microfibers. The above research results can promote the engineering application of Gd-based metallic microfibers in the field of magnetic refrigeration.

In this paper, a new medium entropy alloy with nominal composition of Gd33Co33Al34 was designed and fabricated into microfibers by a melt-extraction method. The microstructure, thermophysical parameters, and magnetocaloric properties of the obtained fibers were systematically analyzed. The results showed that the as-cast fibers show an amorphous matrix with embedded in situ nano crystals. The fibers show a good magnetocaloric effect with the maximum magnetic entropy change of ~6 J/kg·K for a field change of 5 T. Notably, the fibers show excellent cooling efficiencies with an RCP and RC of ~611.72 and ~487.38 J/kg, respectively. Though the as-cast fibers possess an amorphous/nanocrystal bi-phase structure, they still exhibit a second-order transition near a Curie temperature of ~96 K. Our findings provide a promising pathway towards developing new magnetocaloric materials with good magnetocaloric performances.

GMI characteristics of Co-based metallic microfibers under different stresses are tested by stress torsional magneto-impedance comprehensive platform. The internal stress distribution of microfibers is simulated with ANSYS finite element software and the fracture mechanism is analyzed based on fracture morphology. The experimental results indicate that tensile stress can enhance the GMI effect of metallic microfibers, and the significant [ΔZ/Zmax]max of 293.63% at a frequency of 3 MHz is obtained under the tensile stress of 482 MPa. The simulation results demonstrate that the internal stress concentration occurs at clamping end under tensile stress, and which accumulating on the surface of microfibers after applying torsional strain, thus weakening GMI effect. The fracture morphology will change with external stress, some vein-shaped patterns and molten drops can be seen in the cross-section under tensile stress, and the helical vein-shaped patterns appear with the application of torsional strain. In addition, the circular domain wall energy will be increased due to magnetoelastic anisotropy has been affected by tensile stress, which promotes an increment of circular magnetic permeability, thus improving the GMI effect of microfibers. However, the appearance of helical anisotropy after torsional strain is added will weaken the circular domain wall energy.

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Abstract Aims/Introduction In this paper, we focused on exploring the diagnostic and predictive clinical utility of ankle‐brachial index (ABI) in combination with feet electrochemical skin conductance (FESC) for peripheral artery disease (PAD) in Chinese patients with type 2 diabetes mellitus (T2DM). Materials and Methods Overall, 183 Chinese T2DM patients were enrolled in this study. The patients were classified into three groups: Group 1 comprised of uncomplicated type 2 diabetics (n = 36), Group 2 consisted of patients with diabetic peripheral neuropathy (n = 103) whereas Group 3 patients displayed peripheral artery disease (n = 44). All patients underwent Sudoscan test using a Sudoscan (Paris, France) and ABI assessment. Results Multivariate logistic regression models revealed that FESC was an independent risk factor of developing PAD in patients with type 2 diabetes. The AUC for diagnostic, positive predictive and negative predictive value of ABI in combination with FESC for PAD were 0.907, 0.733 and 0.920, respectively. The specificity and sensitivity of ABI in combination with FESC for PAD were 0.914 and 0.750, respectively. Conclusions Ankle‐brachial index in combination with FESC can accurately be used in early diagnosis of PAD.

In this study, the influence of Fe doping on the microstructure and mechanical properties of Gd–Al–Co “metallic glass” fibers (MGF) was systematically investigated, and a fracture mechanics model was constructed based on the fracture morphology of MGF. Furthermore, the mechanism by which Fe doping improves the mechanical properties was revealed. The results indicate that the Gd–Al–Co–Fe series MGF has a typical amorphous structure, and with an appropriate amount of Fe increases the order degree of structure ψ, indicating that a small number of nanocluster micro-regions are formed on the amorphous matrix. With an increase in Fe doping, the tensile strength of MGF presents an initial increase and subsequent decrease. The tensile strength, Rm, of the GdAlCoFe2 MGF was the largest (up to 1199 MPa), and its fracture reliability was also superior (the threshold value of fracture was 581.93 MPa). The tensile fracture of the Gd–Al–Co–Fe series MGF is a flat fracture, showing the characteristics of brittle fracture, with vein-shaped patterns, splitting, and shear bands. A specific amount of nanocluster micro-regions formed by Fe doping effectively hindered the growth rate of crack tips during the stretching and deformation of the microfibers, and significantly improved the mechanical properties of the Gd–Al–Co–Fe series MGF. This study lays the foundation for its engineering applications in the fields of mechanics and machinery.

The production of alloys with high strength and toughness concurrently is still a difficult challenge. Here, we designed a simple solution-ageing heat treatment system to control the morphology and density of α in Ti-15Mo-3Al-2.7Nb-0.2Si via different heat treatment temperatures. The experimental results show that Ti-15Mo-3Al-2.7Nb-0.2Si exhibits a synergistic combination of tensile strength (1364 MPa), plasticity (7.8% elongation), and fracture toughness (101 MPa·m1/2) through solutions in the α/β biphasic region and duplex ageing. Notably, the strength of the alloy after the second step of the ageing process is increased by 15% compared with that after the first step of the ageing process. However, there is less than a 5% reduction in the fracture toughness. TEM observations show that the matrix continues to precipitate denser secondary α during duplex ageing, which causes the strength to increase significantly and causes the fracture toughness to weaken. Our work may provide a novel method to optimize the mechanical properties of alloys by controlling the precipitates.

Herein, the comparative study of tensile and magnetic properties of Fe-based wires formed by rotated-dipping process before and after Nb-doping has been reported. In which, the phase composition, crystallization temperature, surface and fracture morphology, and magnetic performance are respectively investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscope (SEM) and Physical Property Measurement System (PPMS), respectively. Further, the experimental results indicate that the Nb-doped Fe-based wires show an amorphous state, uniform, and continuous, with excellent glass forming ability (GFA) and thermal stability. The saturation magnetization Ms and remanent magnetization Mr decrease owing to Nb-doping, while the coercivity Hc shows an increasing trend with the rising of Nb-doping, reaching 33.0 Oe. The tensile deformation process of Nb-doped Fe-based wires is mainly elastic deformation, reflecting the brittle fracture characteristics. While the Nb-doping can effectively enhance the tensile strength Rm of Fe-based wires, and the Rm of FeSiBNb3 wires exhibits the maximum value of 3.58 GPa. Moreover, the fracture morphology takes on the massive shear bands, and the fracture angles are about 45°, there are also some vein-shaped patterns and molten drops, even the fracture reliability analysis based on the statistical theory of Weibull mechanics indicates that the Nb-doped Fe-based wires possess an obviously improved fracture reliability. Therefore, it can be concluded that the Fe-based wires with improved tensile and magnetic properties as the candidates are adopted for potential electromagnetic and mechanical engineering applications.

Fe–based metallic microwires possess unique microstructure and size effects, exhibiting favorable mechanical, electrical, and magnetic properties, thus distinguishing them as a possible agents for use as microwave absorbing materials. In this paper, the absorbing properties of Ni–doped Fe–based metallic microwires optimized by orthogonal experiments were investigated, and based on the optimal parameters, the influencing mechanism of the Ni doping amount on the absorbing properties was further analyzed. It was noted that at the frequency f = 8.36 GHz, the maximum reflection loss RL and electromagnetic wave absorption efficiency Aeff can reach −54.89 dB and 99.999%, respectively. Moreover, the Ni doping amount could result in the improved wave-absorbing properties of composites, obtain the corresponding optimal parameters, and even change the position of the maximum absorption peak, which are all of great significance for practical engineering applications.

Herein, we have presented the giant magneto-impedance (GMI) effect, microstructure and surface domain structure of the Co-Fe-based amorphous microwires after liquid medium—anhydrous ethanol Joule annealing (AJA). The AJA technique can effectively release the radial stress and induce large a circumferential magnetic field by changing the Joule heat transfer and the circumferential domain, to further tune the GMI performance of microwire. The linear response fields (0~3.5 Oe), the high sensitivity of 124.1%/Oe and the high GMI ratio make the microwire as promising materials for the miniaturized GMI sensors. The GMI ratios of [ΔZ/Z0]max(%) and [ΔZ/Zmax]max(%) increase the near-linearly to 201.9% and 200.5%, respectively, for the 250 mA anhydrous ethanol Joule annealed wires. Moreover, a linear response to Hex (ranging from 3.5 to 25 Oe, or more) is observed, which bears the potential in fabricating bi-sensors.

The preparation of Ni-Mn-Ga and Ni-Mn-Ga-Fe master alloy ingots and microwires was completed by high vacuum electric furnace melt melting furnace and melt drawing liquid forming equipment, and the lattice dislocations and defects formed inside the microwires during the preparation process were corrected by stepwise ordered heat treatment. The micro-structure and phase structure were characterized using a SEM field emission scanning electron microscopy and an XRD diffractometer combined with an EDS energy spectrum analyzer; the martensitic phase transformation process of the microwires was analyzed using a DSC differential scanning calorimeter; and the superelasticity of the microwires was tested by a Q800 dynamic mechanical analyzer. The results indicate that Fe doping can refine the grain, transform the phase structure from parent phase to single 7M martensite, reduce the number of martensitic variants, and increase the mobility of the twin grain boundary interface. The MT phase transition temperature (MS) is substantially increased in the martensite transition (MT) process by the increase of the number of free electrons in its lattice. During the superelasticity (SE) test, both microwires displayed superior recover-ability of SE curves, and the Fe doping curves showed similar characteristics of “linear superelasticity”, showing higher critical stress values and complete SE in the experiment. The critical stress satisfies the Clausius-Clapeyron equation and exhibits higher temperature sensitivity than Ni-Mn-Ga microwires.

Herein, the ordered structure of Co-based metallic microwires was modulated by direct current-annealing, thereby improving the tensile mechanical properties. Based on the thermophysical parameters of the metallic microwires, the annealing current intensities of 65 mA, 90 mA and 150 mA were determined by the method of numerical calculation. The experimental results indicated that the ordered structure of the metallic microwires was regulated under the action of Joule heating, and with the rising of the annealing current, the ordered structure increased and the distribution tended to be concentrated. The 90 mA current-annealed metallic microwires have favorable tensile mechanical properties and fracture reliability, with the tensile strength and elongation of 4540.10 MPa and 2.99%, respectively, and the fracture threshold is 1910.90 MPa. Both the as-cast and current-annealed metallic microwires were brittle fractures, and the fractures consisted of shear deformation regions and crack extension regions. The improvement of the mechanical properties of metallic microwires is related to the nano-ordered structure and their distribution. Under the condition of 90 mA current annealing, the uniformly distributed nano-ordered structures were formed in the amorphous matrix of the metallic microwires, which can effectively slow down the expansion of the shear bands and reduce the possibility of crack generation. This study provides process reference and theoretical guidance for the application of Co-based metallic microwires in the field of stress sensors.

The desirable table-like magnetocaloric effect (MCE) was obtained by designing a new magnetic bed, which comprises three kinds of Gd-based microwire arrays with different Curie temperatures (TC). The TC interval among these wires is ~10 K. This new magnetic bed shows a smooth ferromagnetic to paramagnetic transition at ~100 K. In addition, a table-like magnetic entropy change (ΔSM) was obtained, ranging from ~92 K to ~107 K, with a maximum entropy change (−ΔSMmax) of 9.42 J/kgK for a field change (μ0ΔH) of 5 T. Notably, the calculated results of −ΔSM(T) corresponded to the experimental data for μ0ΔH = 5 T, suggesting that a microwire array-based magnetic bed with desirable magnetocaloric response can be designed. In addition, it was shown that a larger table-like temperature range and cooling efficiency can be achieved by increasing the interval of TC among microwire arrays. These important findings indicate that the newly designed magnetic bed is very promising for active magnetic cooling technology.

Due to the rapid development of bendable electronic products, it is urgent to prepare flexible anode materials with excellent properties, which play a key role in flexible lithium-ion batteries. Although carbon fibers are excellent candidates for preparing flexible anode materials, the low discharge specific capacity prevents their further application. In this paper, a hierarchical porous and silicon (Si)/nitrogen (N) co-doped carbon nanofiber anode was successfully prepared, in which Si doping can improve specific capacity, N doping can improve conductivity, and a fabricated hierarchical porous structure can increase the reactive sites, improve the ion transport rate, and enable the electrolyte to penetrate the inner part of carbon nanofibers to improve the electrolyte/electrode contacting area during the charging–discharging processes. The hierarchical porous and Si/N co-doped carbon nanofiber anode does not require a binder, and is flexible and foldable. Moreover, it exhibits an ultrahigh initial reversible capacity of 1737.2 mAh g−1, stable cycle ability and excellent rate of performance. This work provides a new avenue to develop flexible carbon nanofiber anode materials for lithium-ion batteries with high performance.

Herein, SnO2- and ZnO2-doped (1.5 wt.%) composite Cu powder was prepared by mechanical alloying (MA) respectively, and both the contact materials of oxide-doped Cu alloys were subsequently obtained by canned hot-pressing powder sintering with hot extrusion combined. Scanning electron microscopy (SEM), laser scanning confocal microscopy (LSCM) and self-designed electrical breakdown device were used for investigating the microstructure and properties including electric conductivity and hardness, especially for electrical contact performance of the Cu-SnO2 alloy and in compared with the Cu-ZnO2 alloy. The experimental results show that the hardness of Cu-SnO2 and Cu-ZnO2 contact materials are 103.5±1 HV and 192.7±1 HV, respectively, which meet the hardness standard of national standard electrical contact materials. Meanwhile, the relative conductivity %IACS are 7.24% and 6.20%, respectively, which are higher than the traditional Cu-based contact materials. This electrical life simulation test system was designed independently, and the results indicate that the switching times of Cu-SnO2 contact materials are much more than that of Cu-ZnO2. The addition of SnO2 can effectively improve the arc extinguishing characteristics and the anti-welding performance of the contact materials is enhanced. In summary, SnO2-doped Cu-based contact materials possess excellent comprehensive properties, which can provide reference for potential applications in contact materials.

Purpose: We investigated the effects of Traditional Chinese Medicine (TCM) on the occurrence and progression of albuminuria in patients with type 2 diabetes.Methods: In this randomized, double-blind, multicenter, controlled trial, we enrolled 600 type 2 diabetes without diabetic nephropathy (DN) or with early-stage DN. Patients were randomly assigned (1:1) to receive Liuwei Dihuang Pills (LWDH) (1.5 g daily) and Ginkgo biloba Tablets (24 mg daily) orally or matching placebos for 24 months. The primary endpoint was the change in urinary albumin/creatinine ratio (UACR) from baseline to 24 months.Results: There were 431 patients having UACR data at baseline and 24 months following-up in both groups. Changes of UACR from baseline to follow-up were not affected in both groups: −1.61(−10.24, 7.17) mg/g in the TCM group and −0.73(−7.47, 6.75) mg/g in the control group. For patients with UACR ≥30 mg/g at baseline, LWDH and Ginkgo biloba significantly reduced the UACR value at 24 months [46.21(34.96, 58.96) vs. 20.78(9.62, 38.85), P < 0.05]. Moreover, the change of UACR from baseline to follow-up in the TCM group was significant higher than that in the control group [−25.50(−42.30, −9.56] vs. −20.61(−36.79, 4.31), P < 0.05].Conclusion: LWDH and Ginkgo biloba may attenuate deterioration of albuminuria in type 2 diabetes patients. These results suggest that TCM is a promising option of renoprotective agents for early stage of DN.Trial registration: The study was registered in the Chinese Clinical Trial Registry. (no. ChiCTR-TRC-07000037, chictr.org)

Fracture behaviors of 42CrMo ultrahigh strength steel-based bolt have been experimentally studied including macroscopic and microscopic fracture observation, metallographic test, mechanical property testing, and energy spectrum analysis. The results show that a large amount of structure defects, such as sulfide inclusions, band, and carbon depletion, appear in the fracture origin region and matrix of the bolt. Such defects reduce fatigue strength of materials and easily yields fatigue fracture origin. In addition, sulfide inclusions provide easy access to crack growth, gradually reducing the effective cross section of the bolt accompanying with increasing stress and finally causes fracture when stress exceeds the material fracture strength. The fracture mechanism is also explored based on fracture failure criterion and fatigue crack growth curve.

This work comparatively investigates the influence of alcohol and liquid nitrogen medium-current annealing on GMI effect of rotated-dipping Co-based microwires. The temperature field distribution of Co-based microwires during current-annealing process is accordingly simulated, further to acquire experimental parameters of annealing current. Experimental results indicate that, GMI characteristics of current-annealed microwires in mentioned two mediums are both significantly improved, and GMI ratio [Δ Z / Z _max ] _max and magnetic field response sensitivity ξ _max of alcohol-medium current-annealed microwires increase more observable. When the excitation current frequency f = 3 MHz, [Δ Z / Z _max ] _max and ξ _max of microwires annealed by alcohol medium at 300 mA can reach 240.8% and 78.7%/Oe, respectively. During different type medium-current annealing, the higher-intensity annealing current can generate a larger circular magnetic field, which can effectively regulate the magnetic domain structure of Co-based microwires, so that, they tend to arrange densely and orderly, and the domain walls become much clearer. Meanwhile, the circular permeability μ _φ of microwires is significantly improved, thereby enhancing their GMI characteristics. Accordingly, the medium-current annealed Co-based microwires can be used as a typically sensitive material to provide technical support for the potential application of micromagnetic measurement field.

The Gd55Al20Co25 amorphous wires exhibit a relatively strong magnetocaloric effect (MCE). These melt-extracted amorphous wires display second-order magnetic transition (SOMT) and the value of maximal magnetic entropy (–ΔSm) for the melt-extracted wires is calculated to be ~9.7 J·kg–1·K–1 around the Curie point (TC) of ~110 K with applied field of 5 T. Moreover, the melt-extracted amorphous wires show a high refrigerating efficiency with a relatively large cooling power (RCP, ~804 J·kg–1) and refrigeration capacity (RC, ~580 J·kg–1) under an applied magnetic field of 5T due to the broad paramagnetic-ferromagnetic (PM-FM) region associated with amorphous alloys. These favorable properties make melt-extracted Gd-based amorphous wires to be the potential refrigerant for magnetic refrigeration (MR) of liquid oxygen.

Droplet flight and solidification behaviors during twin-wire arc sprayed (TWAS) composite coatings were systematically investigated. Both theoretical model and numerical method were established for calculating the droplet deformation, breakup and solidification process in air flow based on the volume of fluid (VOF) dual-phase flow model jointed with the standard k-ε model. The experimental simulation results indicate that TWAS droplet is broken through explosion or two steps breaking process. The calculation of TWAS gas flight dynamics demonstrates that the TWAS particles are accelerated at first and then slowed down. Microstructure of the TWAS prepared Ni-5wt.%Al and Ni-20wt.%Al composite coating was accordingly characterized by XRD, SEM and TEM, so the phase compositions of the Ni-Al composite coatings were obtained. TEM analysis also showed that an amorphous phase was formed according to the characteristic of diffraction ring in Ni matrix solid solution at an original state.

Gd60Al20Co20 amorphous wires with smooth surfaces and circular cross-sections were fabricated by a melt-extraction technique. The mechanical properties of the extracted microwires were evaluated by tensile tests and their fracture reliability was estimated by using Lognormal and two- or three- parameter Weibull analysis, respectively. The microwires exhibit a tensile fracture strength ranging from ~788 to ~1196 MPa, with a mean value of 1008 MPa and a standard variance of 121 MPa. Lognormal method of statistical analysis presents that the average stress of microwires is ~1012 MPa. Weibull statistical analysis indicates that the two-parameter tensile Weibull modulus is 8.5 and the three-parameter Weibull modulus is 5.3 with a threshold value ~365 MPa for as-extracted amorphous microwires. Our results show that the extracted Gd-based wires possess excellent tensile properties and high fracture reliability, with a high potential for applications in and magnetic refrigeration.

Giant magneto-impedance (GMI) effect and domain transformation for melt-extracted Co68.15Fe4.35Si12.25B13.25Nb1Cu1 amorphous wires have been induced by a cryogenic Joule annealing (CJA) treatment with different DC current amplitude (0~350 mA) for 240s. Experimental results indicate that the maximum GMI ratio ([ΔΖ∕Ζ0]max) achieves to 188.1% with exciting field increasing to 1.8 Oe monotonically for 300 mA annealing treated wires, which can attribute to the surface complex domain structure change formed by CJA treatment. The liquid nitrogen can protect the wire from crystallization when applied large DC currents. Moreover, the CJA treatment can improve the response sensitivities effectively. These remarkable characteristics make the melt-extracted microwires by CJA tailoring as the promising candidate material for small-sized magnetic sensors.

Ni48Mn26.4Ga19.7Fe5.9 microwires with grain size of 1-3 micron were successfully fabricated by melt-extraction. The superelastic effects in the microwires under various temperatures and loads were systematically demonstrated. The as-extracted microwires displayed partial superelasticity when attended at relatively high temperature. The critical stress for stress-induced martensite formation increases linearly with temperature and follows the Clausius-Clapeyron relationship. The temperature dependence of the as-extracted polycrystalline Ni48Mn26.4Ga19.7Fe5.9 microwires is 16.4 MPa/K, which is higher compared with Ni-Mn-Ga single crystals. In addition, the as-extracted microwires display excellent shape memory behavior with the recovery strain and recovery ratio of 1.26% and 86%, respectively, when the total strain reaches 1.47% at 310 K.

We here report on a comparative study of the microstructure and magnetic properties of as-cast and SPCJA-ed Co-based wires for potential sensor applications. Experimental results indicate that both as-cast and SPCJA-ed wires exhibit typical amorphous feature. There also exists the enhanced local ordering degree of atomic arrangement and obvious transformation (maximum magnetic permeability and minimum saturation magnetization) of magnetic properties after SPCJA treatment, resulting from variation of magnetic moment exchange coupling and magnetic anisotropy by coactions of high-density pulsed magnetic field energy and thermal activation energy. Moreover, SPCJA treatment can drastically improve the GMI property of melt-extracted wires. GMI ratio [ΔZ/Z0]max of 166.07% and field response sensitivity ξmax of 413.76%/Oe by more than 2.25 times and 1.73 times of as-cast wire at 5MHz. Therefore, the SPCJA-ed wire exhibits the improved GMI and magnetic properties at 5MHz~10MHz in contrast to AC annealed wire, which is more suitable for GMI sensor applications working at low-applied-frequency and relatively low-working-magnetic field.

The deformation behavior of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe high strength β titanium alloy is systematically investigated by isothermal compression in α + β field with the deformation temperatures ranging from 1003 K to 1078 K, the strain rates ranging from 0.001 s−1 to 1 s−1 and the height reduction is around 50%. Essentially, the flow stress-strain curve of isothermal compression in α + β field exhibits a flow softening feature when the strain rate is higher than 0.1 s−1 as while it exhibits a steady-state feature as the strain rate is lower than 0.1 s−1. The peak stress increases with a decrease in deformation temperature and the increase of strain rate. The activation energy for deformation in α + β field was calculated and the average activation energy of 271.1 kJ/mol. The microstructure observation reveals that the isothermal deformation in the α + β field of the alloy is mainly controlled by the dynamic recovery mechanism accompanied with the secondary dynamic recrystallizitation of β phase. The α phase shows an obvious pinning effect for the movement of dislocations. During deformation, the α phase was elongated and fragmented.

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.