Amorphous Metallic Alloys Research Articles

Predictive Modeling of High-Entropy Alloys and Amorphous Metallic Alloys Using Machine Learning.

High entropy alloys and amorphous metallic alloys represent two distinct classes of advanced alloy materials, each with unique structural characteristics. Their emergence has garnered considerable interest across the materials science and engineering communities, driven by their promising properties, including exceptional strength. However, their extensive compositional diversity poses substantial challenges for systematic exploration, as traditional experimental approaches and high-throughput calculations struggle to efficiently navigate this vast space. While the recent development in data-driven materials discovery could potentially help, such efforts are hindered by the scarcity of comprehensive data and the lack of robust predictive tools that can effectively link alloy composition with specific properties. To address these challenges, we have deployed a machine-learning-based workflow for feature selection and statistical analysis to afford predictive models that accelerate the data-driven discovery and optimization of these advanced materials. Our methodology is validated through two case studies: (i) a regression analysis of the bulk modulus, and (ii) a classification analysis based on glass-forming ability. The Bayesian-optimized regression model trained for the prediction of bulk modulus achieved an R2 of 0.969, an mean absolute error (MAE) of 3.958 GPa, and an root mean square error (RMSE) of 5.411 GPa, while our classification model for predicting glass-forming ability achieved an F1-score of 0.91, an area-under-the-curve of the receiver-operating-characteristic curve of 0.98, and an accuracy of 0.91. Furthermore, by leveraging a wide array of chemical data from diverse literature sources, we have successfully predicted a broad range of properties. This success underscores the efficacy of our modeling approach and emphasizes the importance of a comprehensive feature analysis and judicious feature selection strategy over a mere reliance on complex modeling techniques.

Stable Operation and Enhanced Sensitivity via Composite Structure Design for Efficient Photoplethysmography and Motion Sensors

Healthcare sensors have attracted lots of interests owing to saving a patient's life by continuously monitoring the patient's health via early diagnosis of the symptoms by using healthcare sensors. Many health-care sensors are available in wearable application that can monitor continuously patient health. There are some common parameters such as a heart rate and human motion that are used to monitor human activity.In order to realize stable operation of health-care sensors, material designs are required considering human-body compatibility. In this research, light-sensors fabricated from low-toxicity organic materials by introducing neutral poly(3,4-ethylenedioxythiophene)-(polystyrene sulfonate) (PEDOT-(PSS)) to improve human-body compatibility as well as to strengthen photoplethysmography (PPG) signal. [1] Neutral PEDOT-(PSS) with heterocyclic 1,3-diazole (HDZ) enhances the polymerization degree, carrier mobility, and other physicochemical properties. Consequently, the presented OPD-based PPG sensor has the ability to diagnose blood circulation status and cardiovascular diseases.Second, we fabricate motion sensors by utilizing metallic glass, i.e., amorphous metallic alloy, which is an alloy composition without grain boundaries and long-range ordering. The unique structure of metallic glass results in excellent tensile strength and strain-resistivity as well as chemical stability to those of conventional metals. The Al-Sm MG-based sensors results in enhanced sensitivity and considerable device stability, because of its amorphous phase. [2][1] Adv. Funct. Mater. 2023, 10.1002/adfm.202309271[2] Electrochimica Acta, 2023, 446, 142053

The problem of protecting a person from the effects of low-frequency electromagnetic fields in modern society. Possible ways to solve it

The paper considers the problem of the impact of low-frequency electromagnetic fields (EMF) generated by electric vehicles (EV) and household appliances on humans in modern society. The data on the effect of EMF on human health and regulatory documents establishing requirements for electromagnetic safety are presented. The method of electromagnetic shielding and materials for the implementation of this method are considered as a promising method for solving the problem. The levels of electromagnetic radiation from a number of EV and household electrical appliances have been experimentally measured. The efficiency of electromagnetic shielding of materials based on single-layer coatings of Ni80Fe20 alloys, multilayer film structures Ni80Fe20/Cu and amorphous metal alloys AMAG172 has been estimated using a computational method. It is shown that electromagnetic screens based on these materials significantly reduce the levels of exposure to EMF of EV and household electrical appliances on humans, which allows us to approach the hygienic standards recommended by doctors and meet the requirements of regulatory documents on remote control.

Atomic and electronic structures of Ni64Zr36 metallic glass under high pressure

Amorphous metallic alloys, also known as metallic glasses (MGs), are materials with unique physical properties resulting from their disordered yet densely packed atomic structure. The packing density of MGs can be further enhanced by external pressure, forcing the decrease of interatomic distances and modifying both the atomic and electronic structure of an alloy. This work reports on classical molecular dynamics (MD) and density functional theory (DFT) studies of Ni64Zr36 MG in a hydrostatic pressure range of 0–120 GPa. The MD simulations revealed that compression leads to enhanced short-range ordering by increasing the contribution of efficiently packed icosahedral-like clusters. According to the DFT calculations, for pressure above 50 GPa, Zr atoms show a significant change in electronic configuration, with a dominant charge transfer from their s and p to d-states and charge redistribution between Ni and Zr atoms. This variation is correlated with the appearance of pairs with significantly shortened interatomic distances, as detected by the MD. We conclude that the enhanced icosahedral ordering in Ni64Zr36 MG is induced not only by the pressure-driven densification of an alloy but also by a variation of its electronic structure.

Effect of Cobalt on the Microstructure of Fe-B-Sn Amorphous Metallic Alloys

Fe78B15Sn7 and (Fe3Co1)78B15Sn7 amorphous metallic alloys were prepared using the method of planar flow casting. The amorphous nature of ribbons containing 7 at. % Sn was verified by X-ray diffraction. The resulting chemical composition was checked by flame atomic absorption spectroscopy and by mass spectrometry with inductively coupled plasma. The microstructure of the as-quenched metallic glasses was investigated by 57-Fe and 119-Sn Mössbauer spectrometry. The experiments were performed with transmission geometry at 300 K, 100 K, and 4.2 K, and in an external magnetic field of 6 T. The replacement of a quarter of the Fe by Co did not cause significant modifications of the hyperfine interactions in the 57-Fe nuclei. The observed minor variations in the local magnetic microstructure were attributed to alterations in the topological short-range order. However, the in-field 57-Fe Mössbauer spectra indicated a misalignment of the partial magnetic moments. On the other hand, the presence of Co considerably affected the local magnetic microstructure of the 119-Sn nuclei. This was probably due to the higher magnetic moment of Co, which induces transfer fields and polarization effects on the diamagnetic Sn atoms.

Giant magneto-impedance effect in amorphous CoP@Cu microstrip based device in a wide frequency range

The giant magneto-impedance effect (GMI) consists in a large variation in the electrical impedance that occurs in some magnetic materials when subjected to a variable external magnetic field. Here we present an experimental study of the GMI in a wide frequency range observed in a structure of the metallic amorphous magnetic alloy CoP electrodeposited on copper microwires by using a microstrip configuration. In the low frequency range, the magnetic field dependence of the impedance is due to the behavior of the circumferential ac susceptibility in the magnetic coating. In the microwave range the behavior of the GMI is dominated by the main dynamical magnetic phenomenon at high frequencies, namely ferromagnetic resonance (FMR). The experimental data are well fit by Kittel equation for the FMR frequency for a ferromagnetic layer with a saturation magnetization similar to the ones reported in previous works. The structural stability of the CoP alloy against aging effects was also investigated. The overall results indicate that the CoP alloy is a good candidate for applications in sensors and in microwave devices.

Non-Homogeneous Plastic Deformation of Amorphous Metallic Alloys under the Action of a Quasi-Static Mechanical Load

Non-Homogeneous Plastic Deformation of Amorphous Metallic Alloys under the Action of a Quasi-Static Mechanical Load

EXPLORING AMORPHOUS ALLOYS: ADVANCED ELECTRON MICROSCOPY AND CLUSTER ANALYSIS

In this study, we explored the atomic structure and orderliness of amorphous alloys through advanced electron microscopy and analytical techniques. Amorphous alloys, characterized by disordered atomic structures, exhibit promising applications in technology. The research addresses a crucial knowledge gap by investigating cluster distribution, particle arrangement, and orderliness within the amorphous matrix. High-resolution electron microscopy (HREM) images are analyzed using diverse algorithms and software tools. The study establishes a correlation between angles approaching 180 degrees and increased orderliness within clusters, highlighting the reliability of angle distribution analysis. Robust indicators, including Div (SP(B/V)) and Div (Mu(B/V)) metrics, assess and compare amorphous alloy samples. Kullback-Leibler (K-L) divergence indicates the significance of cluster ordering, validated by the S-K test. Radial Distribution Function (RDF) analysis uncovers local short-range order, deepening understanding despite limited orderliness discernment. These findings not only enhance our understanding of metallic glasses or amorphous alloys but also offer opportunities for tailored design and improved applications across various technological domains.

Analyzing the effect of elliptical vibration assistance in machining of Zr-based BMG

Bulk metallic glasses (BMGs) are known as amorphous metal alloys that have a distinct advantage compared to crystalline metal alloys due to fewer microstructural defects. Elliptical vibration-assisted machining (EVAM) is a promising technique to improve the machining performance of high-strength materials. This paper addresses a knowledge gap by investigating the chip formation mechanism in EVAM of Zr-BMG considering the shear localization due to its amorphous structure. A coupled thermo-mechanical model including the effect of vibration kinematics on Zr-BMG deformation mechanics is proposed. The effects of tool-workpiece separation, speed ratio, and strain rate on shear stress, temperature, and free volume variations due to chip segmentation are predicted and analyzed. The predicted chip formation from the developed model is validated through the comparison of chip morphology with experimental results of EVAM of Zr-BMG. The model reveals the underlying mechanism of material deformation during EVAM of Zr-BMG. According to the simulations and experimental results, the shear localization phenomena in EVAM is delayed due to insignificant changes in free volume, and enhanced heat dissipation resulted in lower temperatures in the cutting zone caused by tool-workpiece separation. Compared to traditional machining, the disparity in temperature generation and free volume diffusion in EVAM reduces as the speed ratio increases. The suppressed accumulation of periodic shear and thermal stresses at the tool tip increases the tool life in EVAM compared to the fractured tool tip in traditional machining.

Effect of Short Heat Treatment of Amorphous Metal Alloy on Decolorization Dye Mendola Blue

Effect of Short Heat Treatment of Amorphous Metal Alloy on Decolorization Dye Mendola Blue

Механічні властивості аморфних металевих сплавів системи Al87(Ni,Fe)8(REM)5 після короткочасного відпалу

The phase transition temperatures for amorphous metals based on aluminum Al87(Ni,Fe)8(REM)5 system were determined by differential scanning calorimetry (DSC). The mechanisms of formation and growth of nanocrystals in an amorphous matrix were predicted using kinetic models (Matusita model). It was found that after annealing at the temperature of stable nanocrystalline growth, an X-ray amorphous structure with a volume fraction of disordered nanocrystalline phases of solid state of Al(X), GdFe2, AlFe2Ni, GdFe2 for the amorphous metal alloy (AMA) Al87Y4Gd1Ni4Fe4 alloy and microcrystalline phases of solid state of Al(X), GdFe2 AlFe2Ni for the Al87Gd5Ni4Fe4 alloy are formed, which significantly affects the mechanical properties of the Al87(Ni,Fe)8(REM)5 system. The effect of annealing on the mechanical properties of amorphous aluminum-based alloys was investigated using Oliver-Pharr and Young's modulus methods it was found that thermal modification of AMAs: Al87Gd5Ni4Fe4 as a result of heat treatment of AMAs from 5 to 15 min., the microhardness increases from 0.20 GPa to 2.75 GPa, and when heat treated for 60 min at a temperatures of T3 = 645±5 K, 647±5 K, it decreases to 0.35 GPa and 0.45 GPa, respectively.

The Degree of Metallic Alloys Crystallinity Formed under Various Supercooling Conditions

Amorphous metal alloys play an important role in the electrical industry. Studies show the presence of an insignificant proportion of crystals in alloys that are amorphous from the point of view of X-ray diffraction analysis. The crystals significantly affect the mechanical and magnetic properties of amorphous alloys. Therefore, within this work, a comprehensive approach has been developed to determine the degree of crystallinity of amorphous alloys based on theoretical and experimental methods. The study is based on the mathematical model of supercooled melt crystallization previously developed by the authors, which takes into account the patterns of crystal formation and their diffusion and diffusionless growth, taking into account the mutual influence of growing crystals on each other. The mathematical model also takes into account the melt cooling mode when producing amorphous ribbons by cooling the melt on a rotating copper drum. The calculation results have been verified by experiments based on the new technique developed by the authors for calorimetric studies of amorphous ribbons. The developed methodology allows us to determine not only the average fraction of the crystals in a ribbon, but also the patterns of crystal distribution along its thickness as well as the patterns of changes in the proportion of the crystals in ribbons depending on the melt cooling mode.

Nature of anomalous electrical resistance in Co73-xFe4CrxSi12B11 amorphous microwires

Influence of structural relaxation and composition of microwires of metallic amorphous alloys Co73-xFe4CrxSi12B11 (x = 0, 2, 4, 6, 8) on the character and mechanisms of temperature dependence of electrical resistance r(T) has been studied in a wide temperature range (from 4.2 K to crystallization temperature). It is shown that alloys with more than 2 at.% Cr have a number of specific properties, which are significantly differentiate them from Fe- and Ni-rich alloys, as well as many Co-rich amorphous alloys. The features of Cr-doped Co-rich alloys are explained by two reasons: firstly, very strong quantum interference effects of the electron-electron interaction and weak localization of electrons caused by scattering of electrons by the potential created by randomly distributed chromium atoms, and secondly, partially reversible compositional structural relaxation leading to clustering of the amorphous phase at T > 300 °C. It is assumed that the resulting Cr-rich clusters, in which chromium atoms are bonded to metalloid atoms, can enhance these interference effects. The contributions from various mechanisms of interaction and scattering of electrons to the change in electrical resistance with temperature and composition of the alloy are analyzed. The fitting parameters for them are determined and compared with the known data.

Investigation of the Corrosion Properties of Bulk Amorphous Metal Alloys Based on Zirconium

Investigation of the Corrosion Properties of Bulk Amorphous Metal Alloys Based on Zirconium

Self-fluxing amorphous Nickel-based alloys obtained by different techniques. Performance and technological difficulties

Amorphous metal alloys can already be considered advanced structural materials. This structure induces specific properties such as: high mechanical resistance and hardness, high bending ductility, high elastic modulus, superior resistance to corrosion and wear or, depending on the chemical composition, exceptional magnetic properties. The family of self-fluxing alloys based on nickel has multiple applications: NiCrBSi powders are used with remarkable results in obtaining protective layers against corrosion and wear, strips and wires are successfully used as brazing alloys, etc. In this paper it is presented the research carried out for obtaining and characterizing the amorphous NiCrSiB ribbons, through the melt spinning technique and the massive products (bulks) from the same family through mold casting and additive manufacturing using the Selective Laser Melting (SLM) technique

Investigation of the Corrosion Properties of Bulk Amorphous Metal Alloys Based on Zirconium

Investigation of the Corrosion Properties of Bulk Amorphous Metal Alloys Based on Zirconium

(Digital Presentation) Microstructure, Corrosion Resistance, and Magnetic Properties of Amorphous Alloy Co75Si15Fe5Cr4,5Al0,5 before and after Corrosion

Cobalt-based Amorphous Metal Alloys (AMA) can be used as soft magnetic materials in various magnetic devices due to the low value of the natural crystalline magnetic anisotropy. The addition of non-metallic components (Si, B) does not adversely affect the magnetic properties. On the contrary, AMA have high magnetic permeability at low values of coercive force and greater resistance to corrosion compared to crystalline ones.The required important parameters for corrosion description are: the concentration of chloride-ions, the microstructure (especially surface heterogeneity) and the composition of the oxide layer [1]. It was determined that the initial AMA Co75Si15Fe5Cr4.5Al0.5 possesses the low coercive force 0.38 A/m. The modification of the alloy surface with nanostructures by anodizing at different current densities (i) and times in the BmimBF4 ionic liquid (IL) does not affect the value of the coercive force, but its resistance to corrosion in a chloride solution increases. The coercive force increases after corrosion, which may be due to a change in surface morphology.The domain structures of the surface modified with nanostructures and initial alloys are different. After excerption at a constant (i) in IL, the domain structure of the surface consists of relatively large uniformly magnetized regions (Fig. 1a). The coercive force of the sample practically does not change compared to the initial sample.The surface domains after corrosion are broken into smaller ones, while the predominant orientation changes its direction (Fig.1 b). The change in the surface domain structure is accompanied by a significant increase in the coercive force (by a factor of 10), although the maximum magnetic permeability (the slope of the hysteresis loops) does not change.The EIS-tests (electrical impedance spectroscopy) were performed at -200 mV (Ag/AgCl) in the frequency range of 50,000 to 0.01 Hz and an oscillation amplitude of 20 mA in Ringer's solution (Fig.1 c, d) to compare the charge transfer kinetics for modified with nanostructures and initial samples. The simulated equivalent circuit included the values of the solution resistance Rs (22 Ω), the value of the constant phase element CPE associated with the double layer capacity, including the capacitance of the modified surface layer, and Rp is the charge transfer resistance across the interface. The capacity of the double layer is higher for the modified sample (4.28*10-5 Ohm-1*cN vs. 1.88*10-5 Ом-1*сN ) and the resistance value of the material has hardly changed (18000±13.5% Ohm for modified and 15500±3.5% Ohm for unmodified). The values of the phase angle (0.78 - modified and 0.88 - unmodified) indicate a greater heterogeneity of the charge distribution at the boundaries of the double layer for the modified surface of the alloy.So, surface modification affects the corrosion resistance, while it has little effect on the parameters of hysteresis loops, what is very important in practical applications. Nyby, C., Guo, X., Saal, J. E., Chien, S.-C., Gerard, A. Y., Ke, H., Frankel, G. S. (2021). Electrochemical metrics for corrosion resistant alloys. Scientific Data, 8(1).doi:10.1038/s41597-021-00840-y Figure 1

Formation of laser-induced periodic surface structures on Zr-based bulk metallic glasses with different chemical composition

Bulk metallic glasses (BMG) are amorphous metal alloys known for their unique physical and mechanical properties. In the present study, the formation of femtosecond (fs) laser-induced periodic surface structures (LIPSS) on the Zr-based BMGs Zr46Cu46Al8, Zr61Cu25Al12Ti2, Zr52.5Cu17.9Al10Ni14.6Ti5 (Vit105) and Zr57Cu15.4Al10Ni12.6Nb5 (Vit106) was investigated as a function of their different chemical composition. For this purpose, LIPSS were generated on the sample surfaces in an air environment by fs-laser irradiation (λ = 1025 nm, τ = 300 fs, frep = 100 kHz). The surface topography was characterized by scanning electron microscopy and atomic force microscopy. Moreover, the impact of LIPSS formation on the structure and chemical surface composition was analyzed before and after fs-laser irradiation by X-ray diffraction and X-ray photoelectron spectroscopy as well as by transmission electron microscopy in combination with energy dispersive X-ray spectroscopy. Despite the different chemical composition of the investigated BMGs, the fs-laser irradiation resulted in almost similar properties of the generated LIPSS patterns. In the case of Zr61Cu25Al12Ti2, Vit105 and Vit106, the surface analysis revealed the preservation of the amorphous state of the materials during fs-laser irradiation. The study demonstrated the presence of a native oxide layer on all pristine BMGs. In addition, fs-laser irradiation results in the formation of laser-induced oxide layers of larger thickness consisting of an amorphous ZrAlCu-oxide. The precise laser-structuring of BMG surfaces on the nanoscale provides a versatile alternative to thermoplastic forming of BMG surfaces and is of particular interest for the engineering of functional material surfaces.

Excellent impact resistance of multilayer metallic glass films subjected to micro-ballistic impact by overcoming dynamic size effects

Size effects are key issues that hinder the enhancement of impact resistance of films with increasing thickness. In this paper, we consider Ni2Ta amorphous metallic alloy as a prototype thin film and demonstrate that the impact resistance of metallic glass (MG) nanofilms with surface oxidation subjected to micro-ballistic impact can be increased significantly by lamination of thin monolayers, overcoming significantly the size effects in the impact resistance of MG nanofilms. Shear band formation and delamination are the dominant energy dissipation mechanisms for multilayered films under impact. Our molecular dynamics (MD) simulations confirmed that the interfaces between thin layers as modified by surface oxidation play an important role in the impact resistance of the multilayered films. Surface oxidation of multilayered films increases significantly the impact resistance due to oxidation-induced curly structure and the increase of the interfacial strength, which contributes greatly to the energy dissipation during impact. However, excessive oxidation initiates defects near the surfaces of the monolayers to therefore reduce greatly impact resistance of the multilayered films. Our work suggests an effective pathway for fabricating high-performance multilayered MG films with extraordinary impact resistance by overcoming the size effects through the lamination of monolayers.

Capacitor Energy Storage Welding of Ni<sub>63</sub>Cr<sub>12</sub>Fe<sub>4</sub>Si<sub>8</sub>B<sub>13</sub> Amorphous Ribbons

Ni-based metallic amorphous alloys in ribbons shape are used in the manufacture of electrical resistances due to their high electrical resistivity, a value that does not change with temperature. The production of such resistances involves joining processes of amorphous ribbons. The amorphous alloys are difficult to weld by conventional melting processes, even in the presence of inert gas. Consequently, this paper presents the research carried out regarding the capacitor energy storage welding technique of Ni63Cr12Fe4Si8B13 amorphous ribbons. The structural analysis was done by microscopy, X-ray diffraction, and differential scanning calorimetry, and the mechanical behavior was determined by nanoindentation. The joints obtained showed that the proposed welding technology is appropriate for this type of joint.