Onset Of Crystallization Research Articles

Effect of boron oxide and basicity on viscosity and crystallization onset temperature of СаО–SiO<sub>2</sub>–B<sub>2</sub>O<sub>3</sub>–12%Cr<sub>2</sub>O<sub>3</sub>–3%Аl<sub>2</sub>O<sub>3</sub>–8%МgO slag system

The rapid growth of demand for stainless steel and, accordingly, its production, which occurred in the second half of the 20th century and continues till today, makes it necessary to conduct studies of the properties of oxide systems that will contribute to the improvement of metallurgical production technologies for such steel. Therefore, in this paper, using the method of simplex grids for experimental planning and vibration viscometry, a study was conducted of the effect of basicity and boron oxide content on the viscosity and crystallization onset temperature of slags of the СаО–SiO2–B2O3–12%Cr2O3–3%Аl2O3–8%МgO oxide system formed during the reduction period of the production of low-carbon stainless steel by the argon-oxygen decarbonization (AOD) process, which is currently the main method for producing corrosion-resistant steel. The introduction of boron oxide into AOD-slags is a possible solution to the problem of instability of the physical properties of slags during smelting, caused by the volatility of fluorspar fluorides, traditionally used as a flux, and compliance with increasingly stringent environmental requirements by eliminating the formation of toxic fluorine compounds. Based on the results of experimental studies of the viscosity of slags of the studied oxide system depending on the chemical composition and temperature, approximating mathematical models in the form of a reduced third-degree polynomial are constructed. Graphically, the results of mathematical modeling are presented in the form of “composition – property” diagrams, which allow quantitatively determining the effect of temperature and chemical composition of the slags under study on viscosity and their composition on the crystallization onset temperature. It is noted that at 1600 and 1650°C, an increase in the boron oxide content in the slag from 3.0 to 6.0% has a favorable effect on the fluidity of the formed slags in the basicity range of 1.0-2.5. For example, an increase in the boron oxide concentration from 3.0 to 6.0% ensures a decrease in the viscosity of the slags from 2.0 to 0.5 Pa s at a temperature of 1600°C and from 0.4 to 0.3 Pa s at a temperature of 1650°C in the region of increased basicity up to 2.0-2.5.

Modulation of structure and mechanical properties in metallic glass composites reinforced with B2 phase by microalloying

This study investigated the impact of Ta on the structure and properties of Zr46Cu46Al4Ti4)100-xTax (x = 0, 1, 1.5, 2 at%) bulk metallic glass composites (BMGCs). The addition of Ta led to a gradual increase in the glass transition temperature, while the crystallization onset temperature remained nearly constant. This resulted in a decrease in the supercooled liquid phase region and a reduction in the glass-forming ability (GFA). The room temperature uniaxial compression tests revealed that the addition of Ta initially increased the plasticity of the alloys, followed by a subsequent decrease. The alloy with 1.5 at% Ta exhibited superior properties, including the highest fracture strength (2033 MPa) and plasticity (8.1 %). The Vickers hardness tests revealed that the addition of Ta led to an increase of the hardness in the glass matrix region of alloys from 512.8 HV to 550.9 HV. In conclusion, a moderate amount of Ta element can enhance both the fracture strength and plasticity of Zr-based BMGCs, as well as improve the hardness of the alloy glass matrix.

Recrystallization of amorphous AlNbCr coatings irradiated with chromium ions

Applying an AlNbCr layer on the surface of Zr alloys significantly enhances the alloy resistance to oxidation and high-temperature corrosion. However, the effects of irradiation on AlNbCr coating remain largely unexplored. This work investigates the microstructural evolution of Cr ion-irradiated AlNbCr coatings under varying temperatures, utilizing bright-field transmission electron microscopy (TEM) observations and electron diffraction pattern analyses. With increasing Cr ion irradiation dose, the coatings gradually transitioned from an initial amorphous to a crystalline state. The onset of crystallization occurred earlier at higher temperatures, indicating that the crystallization process was significantly influenced by temperature. Moreover, the dynamic crystallization process of the crystalline structure was also analyzed, as well as the different irradiation responses at the Near-Interface Area (NIA) and Far-Interface Area (FIA). These findings provide new insights for understanding and optimizing the performance of AlNbCr coatings in high-irradiation environments.

An Amorphous-to-Anatase Phase Transition Study of TiO2 Nanotubes by Temperature-Dependent Synchrotron-Based In Situ X-ray Diffraction.

TiO2 nanotubes (NTs) with amorphous and crystalline structures have attracted interest due to their wide range of applications, particularly black TiO2, which addresses the limitations of conventional TiO2 (a wide band gap of 3.0-3.2 eV). Understanding the amorphous-to-anatase phase transition is crucial for phase control of crystalline TiO2. This study investigates the size-dependent phase transition behavior of TiO2 and black TiO2 NTs using temperature-dependent synchrotron-based X-ray diffraction. Thermal treatments reveal that phase transitions occur in the ranges of 210-240 °C for normal NTs and 270-300 °C for black NTs. The onset temperature and crystallization growth are dependent on size, especially NT length, at least in the system under investigation. We observe anisotropic crystallization in quantum confinement, with the unit cell undergoing compression in the a-axis and expansion in the c-axis during crystallization. The longest black NTs (BV50T4) show a significant difference in the c/a ratio. Defects, such as oxygen vacancies, localize on specific NT planes.

Time and Temperature Dependence of Drug Crystallization─The Role of Molecular Mobility.

Using the time-temperature-transformation diagrams, we demonstrated a correlation between molecular mobility and crystallization in amorphous solid dispersions of nifedipine (NIF) with each polyvinylpyrrolidone vinyl acetate (PVPVA64) and polyvinyl caprolactam polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus). The behavior was compared with the NIF dispersions prepared with each polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose acetate succinate (HPMCAS) [Lalge et al., Mol. Pharmaceutics 2023, 20(3), 1806-1817]. Each system was characterized by a unique temperature at which the crystallization onset time was the shortest. Below this temperature, a coupling was observed between the α-relaxation time determined by dielectric spectroscopy and crystallization onset time. Above this temperature, the activation barrier for crystallization had a more significant role than molecular mobility. In the solid state, PVP and PVPVA64 dispersion exhibited higher resistance to crystallization than HPMCAS and Soluplus. The role of polymers in inhibiting crystal growth in nucleated systems was discerned by monitoring crystallization following wetting of the amorphous dispersion with the dissolution medium. PVPVA64 and Soluplus dispersions exhibited higher resistance to crystal growth than PVP and HPMCAS.

An Improved Mampel Model of the Non-Isothermal Crystallization Kinetics of Fiber-Reinforced Thermoplastic Composites.

Fiber-reinforced thermoplastic composites (FRTPs) are gaining increasing attention and widespread use in engineering applications due to their high specific strength and stiffness, excellent toughness, and recyclability. The mechanical properties of these composites are closely tied to their crystallization process, making it crucial to accurately describe this phenomenon. Existing theoretical models for analyzing the non-isothermal crystallization of thermoplastic composites often face challenges relating to the complexity of obtaining multiple parameters and the difficulty of achieving a final relative crystallinity of 1. To address these issues, this paper introduces a novel functional form of the crystallization rate parameter K(T), tailored for engineering applications, and proposes an improved Mampel model. This model assumes K(T) to be zero before the onset of crystallization and also to be linearly dependent on temperature thereafter, ensuring that the final relative crystallinity reaches 1. The model requires only two easily accessible parameters: the initial crystallization temperature (Ts) and the linear slope (k). The simplicity of the model makes it particularly well suited to engineering applications. This provides a straightforward and effective tool for describing the non-isothermal crystallization kinetics of fiber-reinforced thermoplastic composites.

Tailoring Crystallization Kinetics in Thin Sucrose Films during Convective Drying: Impact of Temperature and Humidity on Onset, Growth, and Nucleation Rate.

Drying experiments with varying air temperature and humidity were conducted to investigate the influence of the drying process on the crystallization of thin sucrose films. For the first time, the effects of the nucleation onset, nucleation rate, and growth rate were investigated in situ and their differentiated influence on product crystallinity could be assessed. The growth rate was not influenced by air humidity but showed a strong dependence on temperature. It increased with drying temperature; however, at high temperatures, growth was inhibited when the water content falls below a critical level. Noticeable differences in nucleation behavior could be observed with regard to air humidity. Dry air led to crystallization onsets at lower levels of supersaturation, while moderately humid air retarded it. At higher temperatures, nucleation onset commenced at lower water contents but at a constant supersaturation level. The nucleation rate doubled in experiments with moderately humid air (15% RH), while an elevated drying temperature showed generally lower nucleation rates. The observed differences in the nucleation onset and rate could be explained by the film-internal concentration profile, which is strongly influenced by drying parameters. The insights therefore provide a differentiated understanding of the formation of the physical state and how it can be influenced during convective drying.

Photoelectric Characteristics of the Heterojunction n-GaAs-p-(GaAs)1-x-y(Ge2)x(ZnSe)y

The photoelectric properties of n-GaAs – p-(GaAs)1–x–y(Ge2)x(ZnSe)y heterostructures have been investigated both in photodiode and photovoltaic modes. It has been revealed that the spectral dependence of the photocurrent covers a wide range of energy intervals, ranging from 1.07 eV to 3 eV. It has been demonstrated that as the temperature of the crystallization onset (Toc) increases, the peaks of the spectral dependencies of the photoelectromotive force (photo-EMF) shift towards shorter wavelengths. It has been observed that as the crystallization onset temperature (Toc) of the solid solution layer (GaAs)1–x–y(Ge2)x(ZnSe)y increases, the lifetime of photo carriers increases from 10-7 s at Toc=650°C to 5·10-5 s at Toc=730°C. It is demonstrated that the peaks of the intrinsic photoluminescence band shift towards shorter wavelengths with an increase in the temperature of the crystallization onset. Additionally, the study of the intrinsic spectral region of photoluminescence in samples across the thickness of the epitaxial layer confirms the variability of the obtained structures.

Molecular dynamics study of the influence of carbon impurity on austenite nanoparticles crystallization during rapid cooling

The molecular dynamics method was used to study the structure formation during austenite nanoparticles crystallization in the presence of carbon impurities. The paper describes the dependence of the melt cooling rate, particle size, concentration of carbon atoms in the particle on the resulting structure features during crystallization and temperature of the crystallization onset. Formation of the nanocrystalline structure of nanoparticles can be controlled by varying the cooling rate and introducing a carbon impurity: at a cooling rate above 1013 K/s in the model used, crystallization did not have time to occur; at a rate below 5·1012 K/s, the austenite particle crystallized to form a nanocrystalline structure. At the same time, with a decrease in the cooling rate, a decrease in the density of defects in the final structure was observed. At a rate of 5·1011 K/s or less, crystallization of carbon-free particles took place with the formation of low-energy grain boundaries (with a high density of conjugate nodes: special boundaries, twins). The crystallization temperature during cooling at a rate below 1012 K/s is inversely proportional to the particle diameter: as the particle size decreases, the proportion of free surface increases, which leads to a decrease in the probability of crystalline nuclei formation. In addition, the crystallization temperature increases with a decrease in the cooling rate. The introduction of a carbon impurity led to a decrease in the crystallization temperature of nanoparticles: in the presence of 10 at. %. As a percentage of carbon, it decreased by about 200 K for particles of different sizes. Carbon atoms often formed clusters consisting of several carbon atoms. Such clusters distorted the resulting crystal lattice of metal around them, preventing crystallization. In the presence of a carbon impurity, the final structure of the crystallized particles contained a higher density of grain boundaries and other defects. Carbon atoms, especially clusters of them, were fixed mainly at grain boundaries and triple joints.

Prolonged release from lipid nanoemulsions by modification of drug lipophilicity

In addition to the solubilization of poorly water-soluble, highly lipophilic drugs, lipid nanoemulsions bear potential for drug targeting approaches. This requires that the drug remains within the emulsion droplets until they reach the site of action. Since drug release is rather controlled by the lipophilicity of the drug than by the formulation, this study systematically investigated the influence of drug lipophilicity on the course of drug transfer in (physiological) acceptor media. An increase in drug lipophilicity, according to ClogD/P values, was achieved by the formation of lipophilic prodrugs of 5-phenylanthranilic acid – a potential pathoblocker. The range of substances was supplemented by orlistat, lumefantrine and cholesteryl acetate as model drugs. Drug transfer from supercooled trimyristin nanodroplets was determined via differential scanning calorimetry by monitoring their onset crystallization temperature, which decreases linearly with increasing drug content. Release of the model (pro)drugs ranged from burst to hardly any release in the order of the ClogD/P values. Except for cholesteryl acetate, the results were in line with the lipophilicity of the model (pro)drugs estimated by their retention times on a reversed-phase HPLC column under isocratic conditions. An approximate prediction of drug release kinetics was, thus, possible by logP calculations and, to a limited extent, also by reversed-phase HPLC. A further finding was the increased drug loading capacity of the lipid nanoemulsion for lipophilic prodrugs, if the structural changes of the parent compound were accompanied by a lower melting point.

Kinetics study and fragility of (Cu50Zr43Al7)98Y2 bulk metallic glass

Crystallization transformation kinetics and fragility of (Cu50Zr43Al7)98Y2 bulk metallic glass (BMG) were investigated at non-isothermal and isothermal conditions by differential scanning calorimetry. Activation energies for the BMG were calculated for the glass transition, onset crystallization, and crystallization peak using various methods of non-isothermal analysis. Results suggested that atomic rearrangement during glass transition is more complex than crystallization, and growth poses greater challenges than nucleation. Isothermal analysis conducted in the supercooled liquid region provides evidence of crystallization being controlled by diffusion, with a calculated mean Avrami exponent of 2.2. Additionally, the findings of fragility studies and kinetic studies demonstrated a strong correlation with the glass-forming ability (GFA), thereby validating the high GFA of the BMG analyzed in this study. Thus, this research results provide a detailed understanding of the complex crystallization kinetics, thermal behavior, and GFA of (Cu50Zr43Al7)98Y2 BMG, emphasizing its potential in materials science applications.

Surface Morphology and Formation of Nanocrystals in an Amorphous Zr55Cu30Al10Ni5 Alloy under High-Pressure Torsion

A change in the structure of an amorphous Zr55Cu30Al10Ni5 alloy under deformation by high-pressure torsion (HPT) was studied by X-ray diffraction, high-resolution electron microscopy, scanning electron microscopy, and atomic force microscopy. It was found that the uneven distribution of deformation along the radius of the sample, characteristic of deformation by high-pressure torsion, led to the formation of an inhomogeneous structure. The formation of nanocrystals begins at the periphery of the sample. The threshold value of deformation required for crystallization onset was established; the formation of nanocrystals begins in areas with true deformation e = 4.83 or more. An increase in the deformation degree led to an increase in the height of steps on the deformed sample surface and an increase in the roughness of the surface. The thickness of an elementary step that was formed when one shear band came out to the surface was 10 nm, and its height was about 1 nm. It was found that large steps on the deformed surface of the sample had a complex structure and consisted of a large number of elementary steps. The results obtained are important for analyzing the stress distribution and the concentration of free volume in a deformed material, which affect the parameters of the amorphous-nanocrystalline structure formed.

Application of in-line Raman spectroscopy to monitor crystallization and melting processes in milk fat

Anhydrous milk fat (AMF) and its fractions are used as ingredients in a wide range of food applications. Obtaining the appropriate solid fat content (SFC) is essential to achieve the desired product texture. At present, in-line monitoring techniques to control milk fat crystallization and melting are largely unavailable. The thermal behaviour of milk fat (AMF and four of its fractions) was monitored in a temperature-controlled vessel using an in-line Raman analyser and compared with thermograms generated using differential scanning calorimetry (DSC). The major stages of milk fat crystallization and melting were identified using the in-line Raman analyser. Thermal data from DSC showed excellent linear correlations with Raman spectral data (R2 value of 0.97 for the onset of milk fat crystallisation). Partial least squares regression (PLSR) models were developed using Raman spectra to predict SFC with coefficient of determination (R2Cs) from 0.929 to 0.992 and root mean standard error of calibration (RMSECs) ranging from 3.20 to 10.36%. Results demonstrated Raman spectroscopy has significant potential as a way of monitoring milk fat crystallization and melting processes.

Two-step ALD process for non-oxide ceramic deposition: the example of boron nitride

Atomic layer deposition (ALD) based on polymer-derived ceramics (PDCs) chemistry is used for the fabrication of boron nitride thin films from reaction between trichloroborazine and hexamethyldisilazane. The transposition of the PDCs route to ALD is highly appealing for depositing ceramics, especially non-oxide ones, as it offers various molecular precursors. From a two-step approach composed of an ALD process forming a so-called preceramic film and its subsequent ceramization, conformal and homogenous BN layers are successfully synthesized on various inorganic substrates. In the first stage, smooth polyborazine coatings are obtained at a temperature as low as 90 °C. The saturation and self-limitation of the ALD gas-surface reactions are verified. Intriguingly, three ALD windows seem to exist and are attributed to change in ligand exchange. After the ceramization stage using a heat treatment, conformal near-stoichiometric BN layers are obtained. Their structure in terms of crystallinity can be adjusted from amorphous to well-crystalline sp2 phase by controlling the treatment temperature. In particular, a crystallization onset occurs at 1000 °C and well defined sp2 crystalline planes oriented parallel to the surface are noted after ceramization at 1350 °C. Finally, side-modification of the substrate surface induced by the thermal treatment appears to impact on the final BN topography and defect generation.

Fast and Slow Crystallization-driven Convection in White Dwarfs

We investigate crystallization-driven convection in carbon–oxygen white dwarfs. We present a version of the mixing length theory that self-consistently includes the effects of thermal diffusion and composition gradients, and provides solutions for the convective parameters based on the local heat and composition fluxes. Our formulation smoothly transitions between the regimes of fast adiabatic convection at large Peclet number and slow thermohaline convection at low Peclet number. It also allows for both thermally driven and compositionally driven convection, including correctly accounting for the direction of heat transport for compositionally driven convection in a thermally stable background. We use the MESA stellar evolution code to calculate the composition and heat fluxes during crystallization in different models of cooling white dwarfs, and determine the regime of convection and the convective velocity. We find that convection occurs in the regime of slow thermohaline convection during most of the cooling history of the star. However, at the onset of crystallization, the composition flux is large enough to drive fast overturning convection for a short time (∼10 Myr). We estimate the convective velocities in both of these phases and discuss the implications for explaining observed white dwarf magnetic fields with crystallization-driven dynamos.

Accelerated Discovery of (TiZrHf)x(NbTa)1- x High-Entropy Alloys With Superior Thermal Stability and a New Crystallization Mechanism.

Nanocrystalline (nc) metals are generally strong yet thermally unstable, rendering them difficult to process and unsuitable for use, particularly at elevated temperatures. Nc multicomponent and high-entropy alloys (HEAs) are found to offer enhanced thermal stability but only in a few empirically discovered systems out of a vast compositional space. In response, this work develops a combinatorial strategy to accelerate the discovery of nc-(TiZrHf)x(NbTa)1- x alloy library with distinct thermal stability, in terms of phases and grain sizes. Based on synchrotron X-ray diffraction and electron microscopy characterizations, a phase transition is observed from amorphous-crystalline nanocomposites to a body-centered cubic (bcc) phase upon annealing. With increased NbTa content (decreased x value), the system tends to achieve thermally stable dual bcc phases upon annealing; in contrast, alloys with increased TiZrHf content (x > 0.6) maintain a single-composition nanocomposite state, impeding crystallization and grain growth. This investigation not only broadens the understanding of thermal stability but also delves into the onset of crystallization in HEA systems.

Geochemical Thermometry of Ore-Bearing Gabbronorites from the Apophisis of the Yoko-Dovyren Massif: Composition, Amount of Olivine, and Conditions of Sulphide Saturation in the Parental Magma

The temperature and compositional parameters of the parental magma of the ore-bearing apophysis DV10 from the Yoko-Dovyren massif are estimated based on the results of thermodynamic modeling the equilibrium crystallization of melts of 24 samples, following the method of geochemical thermometry. Thermometric calculations were carried out using the COMAGMAT-5.3 program with a step of 0.5 mol. % to a maximum degree of crystallization 75–85% under oxygen fugacity controlled by the QFM buffer. The model order of mineral crystallization corresponds to the sequence: olivine (Ol) + + Cr-Al spinel (Spl) → plagioclase (Pl) → high-Ca pyroxene (Cpx) → orthopyroxene (Opx). Silicate-sulfide immiscibility was modeled to occur mostlybefore the onset of plagioclase crystallization, being consistent with sulfide saturation of the parental magma. The results of calculations demonstrate the convergence and intersection of the model liquid lines of descent at temperatures of about 1185°C. When applied to the average composition of the DV10 apophysis, this temperature indicates the existence of a suspension of the original crystals (52.1 wt. % cumulus olivine (Fo83.6), 2.3 wt. % plagioclase (An79.7), 0.24% clinopyroxene (Mg# 88.8), 1 wt. % aluminochromite (Cr# 0.62)) and about 0.2% sulfide liquid in a moderately magnesian melt (53.6 wt. % SiO2, 7.4 wt. % MgO). At that the solubility of sulfide sulfur (SCSS) was estimated to be 0.083 wt. %. This heterogeneous system had a viscosity of 4.71 log. units (Pa · s) and an integral density of 2929 kg/m3. Such rheological properties do not contradict the possibility of the migration and emplacement of the protocumulus mush from the main Dovyren chamber. However, a more probable scenario includes a localized accumulation of olivine in the trough-like part of the DV10 subchamber, which preceded or occurred in parallel to the accumulation of segregated sulfides.

Influence of nano-CuO modification on crystallization behavior and surface characteristics of P2O5 containing Li2O-ZnO-B2O3-SiO2 glass-ceramics

This paper investigates the impact of nano-CuO addition on the crystallization process and surface properties of phosphate containing lithium zinc borosilicate glass-ceramic coatings. A comprehensive analysis was performed using diverse thermal, structural, and morphological techniques such as hot stage microscope, differential thermal analysis, X-ray diffraction analysis and scanning electron microscopy. Thermal analysis revealed a glass transition temperature of 478.5 °C and a crystallization onset temperature of 595.6 °C. The coefficient of thermal expansion was measured to be 8.94 × 10−6.°C−1. Viscosity measurements indicated a significant decrease in viscosity with increasing temperature, following the Vogel-Fulcher-Tammann equation. Kinetic studies revealed an activation energy of 11.36 kJ/mol for the crystallization process, suggesting potential kinetic hindrance for the reference glass-ceramic coating. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed the formation of a crystalline phases of Li2ZnSiO4 and Li3PO4 at crystallization temperatures above 750 °C. Nano-CuO addition was found to promote crystal formation and increase the inter-crystal spacing according to the SEM analysis. Optical microscopy and 3D surface analysis revealed that nano-CuO addition refined surface texture and reduced the surface roughness of the glass-ceramic coatings at varying crystallization temperatures of 750, 800 and 850 °C. Moreover, contact angle measurements indicated that nano-CuO addition decreased the wetting angle of the coatings around 62 %, suggesting improved hydrophilicity. The findings suggest that nano-CuO addition can enhance the crystallization kinetics and improve the surface quality and hydrophilicity of glass-ceramic coatings.

Reducing part deformation of isotactic polypropylene specimens fabricated with powder bed fusion technique through controlling crystallization behaviors

AbstractSerious shrinkage and warpage are obstacles to the development of ideal isotactic polypropylene (iPP) materials for polymer‐based powder bed fusion (PBF) technique. In this work, the variations of the dimensional accuracy of the PBF‐printed iPP parts were investigated with various printing parameter and nucleating agent. The iPP parts printed at a scanning speed of 700 mm/s exhibit smaller extents of shrinkage and curling than those at lower speeds, due to a lower degree of crystallinity. Interestingly, iPP blended with the α‐ or β‐nucleating agent demonstrates more serious part deformation with respect to neat iPP. Especially, α‐nucleating agent tends to trigger the most severe curling under the investigated printing parameters. Based on X‐ray diffraction and differential scanning calorimetry (DSC) results, both neat iPP and α‐iPP parts crystallize into α‐crystal, while β‐iPP parts display the coexistence of β‐ and α‐crystals. And, the difference of the crystallinity is less than 3% in three specimens. This suggests that both crystallinity and crystalline structure are not the main reasons for the shrinkage and warpage in this case. Instead, the severe part deformation of the α‐iPP parts is assigned to the narrower sintering window as well as the higher onset crystallization temperature of α‐iPP, which hinder relaxation of residual stresses. This work provides insights into the part deformation mechanism for PBF‐processed polymer materials.

Influence of Al addition on the microstructure and properties of Fe25Co25Ni25(Si0.3B0.7)25 high entropy metallic glass

This research work was focused on the development of a new series of high entropy metallic glasses (HE-MGs) combined with higher thermal stability, acceptable soft magnetic property, microhardness and good corrosion resistance by adding various Al content (1–8 at.%) on the basis of Fe25Co25Ni25(Si0·3B0.7)25 high entropy metallic glass using single-roller melt-spinning approach. It is found that the proper addition of Al can efficiently improve the anti-corrosion performance of high entropy metallic glasses, in particular, the corrosion current density is decreased from 7.61 μA/cm2 and 9.26 μA/cm2 for the 1 at.% and 2 at.% Al-added alloys to 5.11 μA/cm2 for the 5 at.% Al-added alloy. However, the improvement of Al content could deteriorate the soft magnetic property and thermal stability of HE-MGs. The saturation magnetization flux density and onset crystallization temperature reduce from 0.85 T to 766.15 K for the 1 at.% Al-added alloy to 0.53 T and 736.75 K for the 8 at.% Al-added alloy. Besides, the Vickers’ microhardness of all investigated alloy ribbons can reach 1124 HV0.2 or above. Therefore, this kind of senary new-type HE-MGs can be used as a promising magnetic shielding metal material with high hardness, superior thermal stability and good anti-corrosion performance for the surface protection of key component in harsh marine corrosive environment.