Iron-gallium Alloys Research Articles

Short-Range Order and Its Stability in a Soft-Magnetic Iron–Gallium Alloy

Short-Range Order and Its Stability in a Soft-Magnetic Iron–Gallium Alloy

Influence of atomic ordering and cerium doping on magnetostrictive Fe-Al alloys

Magnetostrictive iron-aluminum alloys can be a low-cost, mechanically stable alternative to iron-gallium and rare earth-iron alloys. The magnetostrictive performance of polycrystalline Fe-Al (alfenol) with 13–24 at. % Al was investigated, studying the role of compositional variation and thermal history. It was found that rapid cooling enhances the magnetostrictive response, and peak magnetostriction was found in Fe78Al22 by high temperature annealing followed by quenching. Synchrotron diffraction enabled a direct correlation of magnetostrictive behavior and the transition from short-range order to long-range ordered cluster domains in the material which can be suppressed by rapid cooling. Following recent success of doping Fe-Ga with rare earth elements, we investigated the influence of Ce doping on improving magnetostriction and found that Fe-Al shows negligible solubility for cerium, inhibiting potential magnetostriction enhancement. Our results illustrate the complex interplay between phase stability, ordering, and optimized magnetostrictive response.

Experimental study of wind energy harvesting from flow-induced vibration of prisms using magnetostrictive material

A vibration energy harvester was developed using a magnetostrictive material as a power generator and a prism as a wind receiver to harvest energy from low-speed wind by exploiting flow-induced vibration. The present cantilevered vibration power generator has originality for the structure which consists of a U-shaped unimorph beam of Galfenol (iron-gallium alloy). Wind tunnel experiments were conducted for prisms having circular, rectangular, filleted triangular, and V-shaped cross-sections. We focused on transverse vortex-induced vibration for a circular cylinder and low-speed galloping vibration for a rectangular prism with a depth-to-height ratio of 0.2, a filleted triangular prism, and a V-shaped prism. The effect of the width of prisms having a span length of L = 200 mm on the transverse vibration characteristics and the power extracted from the vibration generator was investigated. The maximum power generated by cylindrical, rectangular, filleted triangular, and V-shaped prisms with heights of 50, 50, 60, and 50 mm was 1.28, 3.5, 7.83, and 5.02 mW, respectively. These maximum power levels are enough to run a wireless sensor. Moreover, the angle of the V-shaped prism having a width of 50 mm was varied (i.e., β=60°, 90°, 120°, and 150°) and tested in wind tunnel experiments. The V-shaped prism with β=120° was best from several viewpoints, including low excitation wind speed, safe operation at high wind speed, efficient operation in environmental conditions, and sustainability.

Magnetostrictive Ultrasonic Waveguide Transducer for In-Pile Thermometry

Real-time and reliable temperature measurement on nuclear fuels is crucial for the safe operation of existing pressurized-water reactors and future advanced nuclear reactors. Magnetostrictive materials deform when subjected to a magnetic field or exhibit magnetization variation when stressed. Based on these properties, this study prototyped an ultrasonic thermometer (UT) consisting of a magnetostrictive waveguide, a dc coil providing appropriate magnetic biasing, and an ac coil generating an acoustic impulse and detecting the resulting acoustic echoes. By tracking the time of flight between the excitation pulse and the echoes, the UT can potentially detect nuclear fuel cladding temperature from a long distance. In this study, magnetostrictive iron–gallium alloys, or Galfenol, were selected as the waveguide due to their large magnetostriction, superior temperature survivability, excellent radiation resilience, and high mechanical robustness. A multiphysics finite-element model considering electrical, magnetic, and mechanical dynamics in the magnetostrictive UT was then developed. The model exhibited an error of 0.24% in time-of-flight simulation and, therefore, enabled computer-aided design and guided signal processing. Between room temperature and 120 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C, the new Galfenol-based UT exhibits a linear sensitivity of 162.8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\times 10{^{-6}} {^\circ }$</tex-math></inline-formula> C <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{-1}$</tex-math></inline-formula> , which is 51.7% higher than a previous magnetostrictive UT based on iron–cobalt–vanadium alloys.

Working characteristics of a magnetostrictive vibration energy harvester for rotating car wheels.

The practice of harvesting vibration energy from machine tools, windmill blades, etc., and converting it into electric energy to power low-power electronic circuits has attracted wide attention from experts and scholars. Abundant vibrations that exist in the moving vehicle can be harvested to power sensors in tire pressure monitoring. In this paper, for the first time, a device is proposed to harvest the rotational vibration energy with the iron-gallium alloy (magnetostrictive material) as the core material. Such a device utilizes the coupling characteristics of Villarreal effect and Faraday electromagnetic effect to convert the vibration energy generated by the moving vehicle into electric energy. Upon completion of the design of the magnetostrictive rotational vibration energy harvester, the influence law of key factors, including substrate material, substrate size, and pre-magnetization field arrangement on the harvesting capability of the device, was studied in detail through experiments. An electric motor and vibration exciter were used to apply varied excitation forms to the harvester, and the output patterns of the harvester under conditions of wheel rotation, road bumps, and random vibration were fully analyzed. In addition, the correlation between the deformation of the cantilever beam and harvester performance was also investigated. The results have shown that at the acceleration of 9.6 g and the rotational speed of 90 r/min, the harvester can reach the output voltage of 1.22 V. Consequently, it demonstrates the feasibility of employing the magnetostrictive harvester to gather rotational vibration energy and provides theoretical guidance for further and deeper research on the harvester.

Corrigendum to “Atomic scale understanding of Kurdyumov-Sachs path during BCC to FCC phase transformation in iron-gallium alloy” [Materials Characterization 183 (2022) 111591

Corrigendum to “Atomic scale understanding of Kurdyumov-Sachs path during BCC to FCC phase transformation in iron-gallium alloy” [Materials Characterization 183 (2022) 111591

Magnetic Properties and Substructure of Iron–Gallium Alloy Single Crystals Processed from Ingot to Wafers

Magnetic Properties and Substructure of Iron–Gallium Alloy Single Crystals Processed from Ingot to Wafers

Atomic scale understanding of Kurdyumov-Sachs path during BCC to FCC phase transformation in iron-gallium alloy

The Kurdyumov and Sachs (K-S) orientation relationship between body-centered-cubic (bcc) and face-centered-cubic (fcc) phases has been observed in numerous systems undergone displacive component-involved phase transformations. However, the atomic level evidence for its theoretical path containing two steps of lattice shear is still rare. In this work, we provided an atomic-scale understanding of the K-S path by capturing the early-stage phase transformation from bcc to fcc via a coupled diffusional-displacive mechanism in an aged Fe72Ga28 alloy. Nano-embryonic product phases are directly observed, formed firstly by one lattice shear of (211¯)-bcc planes along [1¯11¯]-bcc direction and further lattice shear of the (011)-bcc planes along [1¯1¯2]-fcc direction. The thermally-activated atomic diffusions are involved in the formation of equilibrium fcc phase. These results may not only help to understand the diverse phase transformations in Fe-Ga alloys, but also add atomistic insights towards the solid-state transformation mechanism between bcc and fcc phases.

Engineering new limits to magnetostriction through metastability in iron-gallium alloys

Magnetostrictive materials transduce magnetic and mechanical energies and when combined with piezoelectric elements, evoke magnetoelectric transduction for high-sensitivity magnetic field sensors and energy-efficient beyond-CMOS technologies. The dearth of ductile, rare-earth-free materials with high magnetostrictive coefficients motivates the discovery of superior materials. Fe1−xGax alloys are amongst the highest performing rare-earth-free magnetostrictive materials; however, magnetostriction becomes sharply suppressed beyond x = 19% due to the formation of a parasitic ordered intermetallic phase. Here, we harness epitaxy to extend the stability of the BCC Fe1−xGax alloy to gallium compositions as high as x = 30% and in so doing dramatically boost the magnetostriction by as much as 10x relative to the bulk and 2x larger than canonical rare-earth based magnetostrictors. A Fe1−xGax − [Pb(Mg1/3Nb2/3)O3]0.7−[PbTiO3]0.3 (PMN-PT) composite magnetoelectric shows robust 90° electrical switching of magnetic anisotropy and a converse magnetoelectric coefficient of 2.0 × 10−5 s m−1. When optimally scaled, this high coefficient implies stable switching at ~80 aJ per bit.

Highway Implementation Test of Battery-Free Health Monitoring System Using Magnetostrictive Vibration Power Generation

In recent years, it has become a world problem that periodic inspection of aging transport infrastructures need huge costs and manpower. As a solution for it, we propose a magnetostrictive vibration power generator from vehicle-induce highway vibrations for battery-free LPWA(Low Power Wide Area) module. We investigate the magnetostrictive vibration power generator, which is suitable for power supply because it has features of simple, robust, and high output. In this paper, we applied this generator to vehicle-induced highway vibration. First, we scale up our generators for increasing output power to generate practical electric power under highway vibrations. The size of the large type generator is 150mm×60mm×50mm and 0.6kg in weight utilizing 16mm×2mm×50mm plate of iron-gallium (Fe-Ga) alloy. Then, we reproduced the highway vibrations in laboratory with simulative vibration experiment system to measure character of generator. We confirmed that it generates a peak voltage of 7V, instantaneous maximum power of 36mW, and total power 52mJ from reproduced highway vibrations for 5minutes. Finally, we tested this system in field, and succeeded in activating battery-free LPWA modules from vehicle-induced highway vibration.

Improved magnetostriction in Galfenol alloys by aligning crystal growth direction along easy magnetization axis

Galfenol (Iron-gallium) alloys have attracted significant attention as the promising magnetostrictive materials. However, the as-cast Galfenols exhibit the magnetostriction within the range of 20–60 ppm, far below the requirements of high-resolution functional devices. Here, based on the geometric crystallographic relationship, we propose to utilize the 90°-domain switching to improve the magnetostriction of Galfenols by tuning the crystal growth direction (CGD) along the easy magnetization axis (EMA). Our first-principles calculations demonstrate that Pt doping can tune the CGD of Galfenol from [110] to [100], conforming to the EMA. Then, it is experimentally verified in the (Fe0.83Ga0.17)100−xPtx (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) alloys and the magnetostriction is greatly improved from 39 ppm (x = 0, as-cast) to 103 ppm (x = 0.8, as-cast) and 188 ppm (x = 0.8, directionally solidified), accompanying with the increasing CGD alignment along [100]. The present study provides a novel approach to design and develop high-performance magnetostrictive materials.

Magnetostrictive iron–gallium alloy harvester with efficient two-mode AC–DC converting technology for effective vibration energy harvesting

A magnetostrictive vibration energy harvester based on an iron–gallium alloy composite cantilever beam is developed, and its capability is optimized from the aspects of bias magnetic field and the number of active layers. To solve the issue of low and irregular output voltage, it designs a converter suitable for a low-power harvester to make full use of the generated electric energy. A set of AC–DC converters with two working modes is designed by using the multiple voltage rectification method, which is able to directly drive low power load or store energy to supply power to higher power load. Through theoretical simulation and experiment, the converter’s characteristics, such as rectifier and filter characteristics, energy storage, and release process are systematically studied and tested. 1 V AC output voltage of the harvester is able to be converted into 5 V DC voltage after being processed by the converter. The proposed harvester provides an excellent vibration harvesting capacity that the AC normalized power density (power density per volume and acceleration) reaches 7.4 mW/(cm3/g). The harvesting system with the two-mode converter has achieved a high normalized DC output power vs AC input voltage of 630 µW/V. We have applied the harvester and converter for a low power electronic meter, which can work normally and display the time, temperature, and humidity in the laboratory. In addition, we have also applied the harvesting system for a higher power (1.2 W) electric fan with a universal serial bus (USB) port. After battery charging and IP5306 voltage boosting, the harvester meets the normal operation requirements of an electric fan with a USB port and it is able to operate normally.

Effect of Magnetic Field Annealing on Magnetic Properties of Iron–Gallium Alloys

The concentration dependence of magnetic properties of iron alloys with 3–25% of gallium is studied. It was shown that the saturation induction monotonically decreases with increasing gallium content, while the coercivity exhibits a step increase with a step from 85 to 135 A/m between 12 and 15 at % Ga. The effect of magnetic field annealing (MFA) on the behavior of the residual induction and coercive force in alloy samples containing from 3 to 18 at % Ga is studied. As a result of MFA, magnetic anisotropy is induced in the alloy: magnetic hysteresis loops become narrower, the residual induction increases, and the coercivity decreases. The MFA efficiency reaches a maximum at a Ga content of 15–18 at %. The features of the structure state of iron–gallium alloys and their role in the formation of magnetic properties during annealing in a dc magnetic field are discussed.

Surface characterization of functional iron–gallium alloys annealed under different conditions

Fe–Ga alloys are functional magnetostrictive materials, which are promising for application in actuators and sensors. Because surface properties of these alloys such as corrosion resistance are important in technological applications, it is required to characterize the chemical composition and state of the surface of these alloys, which depend on annealing conditions. In this study, X‐ray absorption spectroscopy (XAS) and secondary ion mass spectrometry (SIMS) were used to characterize surface layers formed on the Fe–Ga alloys annealed under different atmospheric conditions. The XAS spectra of the annealed sample showed that the amount of gallium in the surface layers increased due to annealing, whereas the XAS spectra of the as‐polished alloys revealed that the amounts of iron and gallium arise from the bulk composition. The XAS spectra of the alloys annealed in argon–hydrogen with residual oxygen showed that gallium is increased for its preferential oxidation. SIMS depth profile also showed the enrichment of gallium on the surface and the inhomogeneous distribution of iron on the surface layers.

Analysis of the Key Factors Affecting the Capability and Optimization for Magnetostrictive Iron-Gallium Alloy Ambient Vibration Harvesters.

The basic phenomena of a cantilever energy harvesting device based on iron-gallium alloy magnetostrictive material for low frequency were systematically studied. The results highlighted how the physical parameters, geometric structure and bias conditions affected the vibration harvesting capacity through a thorough experimental aimed at enhancing the vibration energy harvesting capacity through an optimal design. How the performance is affected by the configuration of the multi-layers composite beam, material and dimensions of the elastic layer, arrangement position and number of bias magnets, the matching load resistance and other important design parameters was studied in depth. For the first time, it was clearly confirmed that the magnetic field of bias magnets and electromagnetic vibration shaker have almost no effect on the measurement of the voltage induced from the harvester. A harvesting power RMS up to 13.3 mW and power density RMS up to 3.7 mW/cm3/g was observed from the optimized prototype. Correspondingly, the DC output power and power density after the two-stage signal processing circuit were up to 5.2 mW and 1.45 mW/cm3/g, respectively. The prototype successfully powered multiple red light emitting diode lamps connected in a sinusoidal shape and multiple red digital display tubes, which verified the vibration harvesting capability or electricity-generating capability of the harvester prototype and the effectiveness of the signal converter.

Влияние отжига в постоянном магнитном поле на магнитные свойства сплавов железо--галлий

The concentration dependence of the magnetic properties of iron alloys with 3 – 25 at.% gallium has been studied. It is shown that with increasing gallium content, saturation induction decreases monotonically, but coercive force shows a stepped increase with a jump from 85 to 135 A/m between 12 and 15 at.% Ga. The effect of annealing in a dc magnetic field (magnetic field annealing (MFA)) on the behavior of residual induction and coercive force in samples containing from 3 to 18 at.% of gallium was investigated. After the MFA, in the alloy a magnetic anisotropy is induced: magnetic hysteresis loops become narrower, the residual induction increases and the coercive force decreases. The MFA efficiency reaches a maximum when the gallium content is at 15 – 18 at.%. The features of the structural state in iron-gallium alloys and their role in the formation of the magnetic properties during annealing in the dc magnetic field are discussed.

Performance optimization of magnetostrictive guided wave sensor based on waveguide wire

In this paper, an open magnetic circuit magnetostrictive guided wave sensor that allows free regulation of the static working point is proposed for ferromagnetic material waveguide wires applied to non-destructive testing of wire bars, guided wave mechanics study, magnetostrictive linear displacement sensors and other fields. The sensor was made up of an iron-gallium alloy wire, a ring-shaped permanent magnet and a concentric coil, which was used to excited a longitudinal mode guided wave on the iron-gallium alloy wire. The structural parameters of the permanent magnet were optimized, the axial relative distance between the permanent magnet and the coil was studied and the superposition of and matching between the dynamic magnetic field and the static bias magnetic field were adjusted, allowing identifying the optimal magnetization point, so that the magnetic acoustic transduction efficiency was optimized. The sensor was analyzed, by means of finite element simulation, to produce the best system combination, which improved the sensitivity of the measurement. The improvement has been experimentally verified.

Bio-Inspired Magnetostrictive Tactile Sensor for Surface Material Recognition

The tactile perception of an object’s surface material plays an important role in many intelligent fields including object recognition, robotic grasp, and environment exploration. Enlightened by the human active tactile perception process that originates from scanning a finger on the surface, a novel finger-like tactile sensor for surface material recognition has been designed according to the transduction mechanism of cilia and Villari effect of the iron–gallium alloy. Based on the structural dynamic theory of Euler–Bernoulli beam, the linear constitutive equations of magetostrictive material and the Faraday law of electromagnetic induction, the output voltage model of the sensor under vibration induced from the fingertip-surface scanning has been established. Furthermore, a prototype of the sensor, on the macroscale, is fabricated. In order to verify the performance, the sensor is used to measure induced vibration signals with texture properties during sliding on the surface and classify five similar texture surfaces with small differences with a classification algorithm. The experimental results indicate that the proposed tactile sensor is effective and highly accurate for surface material classification. The sensor is characterized by high sensitivity and quick response. It has the potential of being miniaturized and integrated into the finger of a robotic hand to realize surface material recognition in real time.

Computationally efficient locally linearized constitutive model for magnetostrictive materials

This paper presents a computationally efficient constitutive model for magnetostrictive materials. High computational efficiency is achieved through the use of local linearization (about easy axes) and discrete energy-averaging techniques. The model is applied to iron-gallium alloys (Galfenol) and tested for different magnetic field orientations relative to the easy axes. It is observed that the model accurately predicts both sensing and actuation characteristics while reducing the computation time by a large factor (&amp;gt;1000 times) when compared to the nonlinear energy minimization models. Furthermore, the average error observed in λ–H and B–H curves is less than 3.5% with the error increasing at magnetic field orientations farther from easy axes, particularly at large magnetic field values. Finally, the model is integrated with a finite element framework to predict the response of a Galfenol rod transducer system, and parametric studies are performed for different current and prestress conditions to optimize the device performance.

The Usage of Hydroextrusion for Plastic Deformation of Magnetostrictive Iron-Gallium Alloys

For the first time hydroextrusion process was chosen for Fe-Ga ingots deformation with a gallium content of 19 and 20 at.%. The samples were annealed at 950oC, followed by air cooling. Structure of deformation and primary recrystallyzation were investigated by the method of electron back-scattered diffraction (EBSD). The degree of hydroextrusion deformation achieved was 28 – 42 %. There was not found any crystallographic texture at such degree of deformation. The value of magnetostriction in recrystallization sample was about 100 ppm. Available in literature methods and approaches to creation of the Fe-Ga samples from the point of view of receiving high magnetostriction and also a possibility of machining of the samples are discussed.