Onset Crystallization Temperature Research Articles

Effect of Ethylene Comonomer Content on the Foam Processing Window of Long-Chain Branched Polypropylene

The non-optimized foam processing window (FPW) can create processing challenges and limit the possible materials with which a polymer of interest can be processed in emerging foaming technologies. To address this drawback, we aim to investigate the effect of ethylene comonomer content on the foaming behavior of polypropylene (PP), particularly the FPW. Two PP resins containing 0.75 and 1.5 wt % of ethylene comonomers were studied, while using a PP homopolymer as a control. High-pressure differential scanning calorimetry confirmed the decrease in the onset crystallization (Tc-onset) and end melting (Tm-end) temperatures with increasing ethylene comonomer content as a result of the defects the ethylene units induce in the crystalline structure of PP. Rheological measurements suggest that the addition of ethylene comonomer content resulted in negligible changes in the extensional and shear rheological responses of the PP-based resins. In addition, the foam expansion results and the observed morphologies reveal no significant change in the resins’ foamability, characterized by the shape of their expansion profiles with respect to the foaming temperature. Interestingly, the FPW was found to be the sole affected parameter, as 1.5 wt % of ethylene comonomers resulted in a 10 °C shift in the FPW toward lower temperatures, compared to the PP homopolymer. The resins with 0 and 1.5 wt % of ethylene comonomer content showed similar mechanical responses under compression tests for their optimally expanded samples. These findings reveal a potentially effective approach for tuning the FPW of processed PP resins without compromising their foaming and mechanical performances. Consequently, foam processing techniques are further enhanced, resulting in a wider span of potential applications.

Magnetic properties and nanocrystallization behavior of Co-based amorphous alloy

The magnetic properties of the amorphous Co57Fe5Ni10Si11B17 alloy have been studied by a vibrating sample magnetometer. The temperature dependence of saturation magnetization was measured and the Curie point and crystallization onset temperature were determined as 560 K and 760 K respectively. The coercive force was obtained as 200 A/m and saturation magnetization - 65 Am2 /kg. The alloy was produced in the form of a ribbon thickness of 30 µm using the melt spinning method, and its internal amorphous structure was examined by the X-ray diffraction method. The crystallization behavior of the alloy was studied using series of isothermal annealing of the samples of the alloy at temperatures in the range of 723-1023 K for different exposures (up to 240 minutes) and nanocrystalline phases were detected by the X-ray diffraction analysis.

A Comprehensive Study of Sn-Ga2Te3-SnTe Amorphous Alloys: Glass Formation and Crystallization Kinetics

In this paper, newly developed tellurium-based [(Ga2Te3)34(SnTe)66]100-x-Snx amorphous alloys were prepared by the melt-spun method, with a linear velocity of 40 m/s and injection pressure of 20 kPa under an Ar atmosphere. The glass-forming region was identified in the range of x = 0 to 10 mol%. The glass transition temperature Tg and crystallization onset temperature Tc decreased monotonically with the increasing Sn content in the whole compositional range, resulting in the decrease in the stability criterion ΔT from 33 K (S2) to 23 K (S10). The crystallization kinetics were systematically investigated based on the differential scanning calorimeter (DSC) under non-isothermal conditions. The activation energies of the S8 amorphous sample determined by Kissinger and Ozawa equations were Eg (201.1~209.6 kJ/mol), Ec (188.7~198.3 kJ/mol), Ep1 (229.8~240.1 kJ/mol) and Ep2 (264.2~272.6 kJ/mol), respectively. The microscopic structure of the S8 amorphous sample and its annealed glass-ceramics were also analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). The crystalline products were identified as having a SnTe phase (primary crystalline phase) and Ga6SnTe10 phase, thus providing a promising candidate for the development of high-performance thermoelectric glass-ceramic materials.

Structural, Crystallization Kinetics and Physical Properties of Se85Te15−xAgx Chalcogenide Glasses

In this study, Se85Te15−xAgx (x = 3, 6, 9 and 12) chalcogenide glasses were examined for their structure, crystallization kinetics, and physical characteristics. The kinetics of crystallization in these glasses were studied using various methods. By using the melt quenching process, Se85Te15−xAgx bulk alloys were created. The amorphous nature of the alloys was confirmed using High Resolution X-Ray Diffraction (HRXRD). The crystallization kinetics of the Se85Te15−xAgx glasses were studied using non-isothermal differential scanning calorimetry (DSC) measurements at heating speeds of 5, 10, 15, 20 and 25 K/min. The different characteristic temperatures, including the glass transition (Tg) and on-set crystallization (Tc) temperatures, have been determined from a variety of DSC thermograms. Using the Kissinger and Moynihan techniques, the activation energies of the glass transition (ΔEt) were computed.

Flexible stretchable SEBS/n-alkane phase change composite films for highly efficient thermal management and infrared stealth applications

Phase change materials (PCMs) can alleviate concerns about energy to a certain extent by reversibly storing a plenty of renewable and sustainable thermal energy. However, they do not have any flexibility due to their liquid leakage and solid rigidity, making them unsuitable for further practical wearable applications. Herein, a series of SEBS/n-alkane PCM composite films (PCMFs) were fabricated. SEBS is mainly used as the supporting substrate to prevent the leakage of liquid n-alkanes and endue the PCMFs with excellent mechanical properties. Where, the tensile strain and tensile strength of SEBS/n-HD-50% PCMF separately are 780% and 9.96 MPa, representing excellent stretchability and deformability, tailorability, and foldability. Particularly, the onset melting and crystallization temperatures (Tmo, Tco) of SEBS/n-ES-50% and SEBS/n-DS-50% PCMFs individually are 28.1 °C and 28.4 °C, 33.8 °C and 35.7 °C, which match the comfort zone for human skin and the ideal thermo-response temperature range of smart windows, and a range of experiments have verified their feasibility in the fields of thermal management, smart windows and infrared stealth. This study well solves the problems of liquid leakage and solid rigidity of PCMs themselves, endows them with excellent comprehensive performance, and greatly expanding the practical applications of PCMs.

Observation of electrical threshold switching behavior and thermal crystallization in bulk Se86-xTe14Snx chalcogenide glasses

Selenium-rich chalcogenides have gained popularity as materials for selector devices due to their unique Ovonic Threshold Switching behavior. Bulk Se86-xTe14Snx glassy alloys (0 ≤ x ≤ 6) were prepared through the traditional melt quenching method. The samples with Sn atomic percentage (x) = 3 to 6 are found to exhibit a rapid and reversible transition between a highly resistive and conductive state affected by an electric field. A remarkable decrement in threshold voltage (Vth) from 453 V to 62 V has been observed with increase in the Tin content. Differential scanning calorimetry (DSC) analysis was carried out to understand the variation of Glass transition temperature (Tg), Crystallization temperature (Tc), and other important glass stability parameters and their compositional dependence. Se82Te14Sn4 sample was found to be thermally most stable with Herby’s parameter value (HR) of 0.3860 and a maximum number of switching cycles at room temperature. X-Ray diffraction patterns of annealed samples were compared with pristine glass to study the multi-phasic Se–Te–Sn alloy. Further, the threshold voltage (Vth) and the number of threshold switching cycles are found to decrease with an increase in temperature till crystallization on-set temperature (Toc). The temperature-dependent conductivity studies showed an abrupt increase in the conductivity of the samples as the temperature crossed the crystallization onset temperature.

Crystallization characteristics of Li2O–Nb2O5 compound films on sapphire substrates and formation of crack-free and thick LiNbO3 epitaxial films

The formation of crystal phases in Li 2 O–Nb 2 O 5 compound films deposited on sapphire C-plane and A-plane substrates was studied by X-ray diffraction. Sufficiently oxidized samples with Li-deficient or stoichiometric compositions were prepared by co-sputtering from LiNbO 3 (LN) and Li 2 O targets. Crystallization during deposition at elevated temperatures and solid-phase crystallization (SPC) of deposited amorphous films were investigated. For films on sapphire C-planes, nucleation into Li 3 NbO 4 (222) domains occurred at the onset temperature of crystallization. In the case of stoichiometric films, the LN(006) signal indicating epitaxial growth was the primary one for crystallization during deposition above 460 °C and SPC above 750 °C. Misoriented LN(104) domains tended to coexist with LN(006) domains. In the case of Li-deficient films, LiNb 3 O 8 (_602) domains coexisted with LN(006) at temperatures above 750 °C as a result of Li 2 O loss. For films on sapphire A-planes, epitaxial LN(110) domains were predominant. Li 3 NbO 4 (222) domains were totally absent and the signal intensity of LiNb 3 O 8 (212) was less than 10% of that of LN(110) even for the Li-deficient films, which reflected fast crystallization of LN(110) domains. The SPC rate of stoichiometric film was considerably lower than that of Li-deficient film. As-crystallized LN film on the sapphire C-plane was strained with a narrow domain width. Thick film cracked as a result of stress caused by lattice mismatch with the substrate. In contrast, LN film processed by SPC was not strained and had large domains with flat film surface. Based on these results, crack-free 1-μm-thick LN epitaxial films on a sapphire C-plane were achieved. First, an amorphous LN buffer was subject to SPC to obtain a relaxed buffer layer. Subsequently, a stress-free thick LN overlayer was grown by co-sputtering from Li 2 O and LN targets at 530 °C. The relaxed buffer layer effectively mitigated the strain caused by the lattice mismatch with the substrate.

High-Temperature Response Polylactic Acid Composites by Tuning Double-Percolated Structures.

Due to the properties of a positive temperature coefficient (PTC) effect and a negative temperature coefficient (NTC) effect, electrically conductive polymer composites (CPCs) have been widely used in polymer thermistors. A dual percolated conductive microstructure was prepared by introducing the polybutylene adipate terephthalate phase (PBAT) into graphene nanoplatelets (GNPs)-filled polylactic acid (PLA) composites, intending to develop a favorable and stable PTC material. To achieve this strategy, GNPs were selectively distributed in the PBAT phase by injection molding. In this study, we investigated the crystallization behavior, electrical conductivity, and temperature response of GNP-filled PLA/PBAT composites. The introduction of GNPs into PLA significantly increased PLA crystallization capacity, where the crystallization onset temperature (To) is raised from 116.7 °C to 134.7 °C, and the crystallization half-time (t1/2) decreases from 35.8 min to 27.3 min. The addition of 5 wt% PBAT increases the electrical conductivity of PLA/PBAT/GNPs composites by almost two orders of magnitude when compared to PLA/GNPs counterparts. The temperature of the heat treatment is also found to play a role in affecting the electrical conductivity of PLA-based composites. Increasing crystallinity is favorable for increasing electrical conductivity. PLA/PBAT/GNPs composites also show a significant positive temperature coefficient, which is reflected in the temperature-electrical resistance cycling tests.

Modulation of soft magnetic properties of Fe83B10P4C2Cu1 amorphous alloys by V addition and annealing treatment

In this work, Fe83-xB10P4C2Cu1Vx (x = 0, 0.5, 1, 2) amorphous alloys were designed and prepared to further enhance the soft magnetic properties of the alloys. The effects of V addition on the thermal stability, the soft magnetic properties, and the microstructure after annealing treatment were investigated systematically. The results show that it effectively enhances the thermal stability of the amorphous alloys, as evidenced by the obvious increase of the onset crystallization temperature. Proper annealing near onset crystallization temperature can obtain uniformly distributed nanocrystalline particles in the amorphous substrate, which is helpful to modulate the soft magnetic properties of the alloy. The amorphous/nanocrystalline composite structure that generated in 5 min annealing will further enhance the saturation magnetization of the Fe82.5B10P4C2Cu1V0.5 alloy from 162.5 Am2/kg to 172.2 Am2/kg, and significantly ameliorate the coercivity from 3440 A/m to 1430 A/m, which is obviously optimized compared to that of the as spun alloy.

Effect of Ge on soft magnetic properties at elevated temperature for Si-rich Finemet-type alloy

• The effect of Ge doping on the soft magnetic properties is investigated for Si-rich Finement-type alloy. • The Curie temperature is enhanced by doping Ge in Si-rich Finemet-type alloy. • The initial permeability μ i of 540°C-annealed Fe 72 Ge 2.5 Cu 1 Nb 3 Si 17.5 B 5 alloy possesses a relatively large value of 5000 until 600°C. The results obtained by partially substituting Ge for Fe in the Fe-based nanocrystalline alloy for improving the magnetic properties at high temperatures are presented in this work. These studies were performed on the Fe 74.5- x Ge x Cu 1 Nb 2 Si 17.5 B 5 ( x =2.5, 5, 7.5) alloys. The nanocrystallization and the Curie temperature are dependent on the Ge concentration. The onset temperature of primary crystallization decreases with the increase of Ge, indicating that the dual-phase nanocrystalline structure could be formed at a relatively lower temperature compared with the Ge-free alloy . For the alloy with x =2.5at%, the Curie temperature of the amorphous alloy is enhanced to 405°C. The initial permeability μ i of 540°C-annealed alloy possesses a relatively large value of 5000 until 600°C. Such a magnetic softness at elevated temperature is superior to that of Finemet-type Fe-based nanocrystalline alloys ever reported.

Effect of Recycling on the Mechanical, Thermal and Rheological Properties of Polypropylene/Carbon Nanotube Composites

In this research the effect of physical recycling on the mechanical, thermal, and rheological properties of polypropylene (PP)/multiwalled carbon nanotube (MWCNT) was investigated. After melt homogenization by extrusion, specimens were injection moulded with 0.1 and 0.5 wt% MWCNT content. The recycling process was simulated by multiple grinding and re-moulding, then we compared the behavior of original and recycled PP/MWCNT composites. Differential scanning calorimetry (DSC) measurements proved that MWCNT had double the effect on the morphology of the PP matrix: on the one hand nucleating effect can be detected because 0.5 wt% MWCNT increased the onset temperature of crystallization by 10 °C, compared to the basic PP material; on the other hand, the crystalline fraction of the recycled composite materials decreased compared to the original PP material with the same MWCNT content. This resulted in a slight decrease in strength and stiffness but an increase in elongation at break. However, compared to the original unreinforced PP reference, even the recycled materials have better properties. The mechanical test results showed that recycled PP/MWCNT 0.5 wt% increased the elastic modulus (~15%) and decreased the tensile strain at yield (~10%). However, in the values of tensile stress at yield, relevant difference was not found. It was also shown by oscillatory rheometry that MWCNT had a significant effect on the rheological properties (storage and loss modulus, complex viscosity) of PP compounds in a wide temperature range (190-230 °C).

The effect of Ta addition on mechanical properties of Zr-based bulk metallic glasses

Bulk metallic glasses (BMGs) exhibit poor room temperature plasticity, so improving their room temperature plasticity is important for amorphous alloys in engineering applications. In this paper, Zr60Cu(20-x)Al10Ni10Tax (x = 0, 1, 3, 5) bulk metallic glasses with 3 mm diameter rods were prepared by water-cooled copper mold suction casting, and investigated the effect of minor additions of Ta on the properties of Zr–Cu–Ni–Al alloys, especially on plasticity. The results show that the Zr-based alloys with a 3 mm diameter are amorphous. With the addition of Ta elements, the glass transition temperature hardly changed, the crystallization onset temperature increased from 747 K to 767 K, the width of the supercooled liquid phase zone increased from 49 K to 68 K, and the thermal stability of the alloy was improved. The room temperature uniaxial compression test found that with the increase of Ta content, the strength and plasticity of alloys showed a trend of first increasing and then decreasing, when the Ta content was 1 at.%, more interactive shear bands were observed on the side surface of the alloy after compression, while the fracture surface exhibited a complete vein pattern, and fracture strength and plasticity of samples reached to 1920 MPa and 13.8%, respectively. The results of nanoindentation tests indicated that when the Ta content was 1 at.%, the alloy exhibited the maximum indentation hardness and elastic modulus of 8.03 GPa and 101.48 GPa, respectively. It can be concluded that the right amount of Ta in Zr-based BMGs improves the mechanical properties, especially, the fracture strength, the plasticity, the indentation hardness, and the elastic modulus.

Effect of W Addition on Fe-P-C-B Soft-Magnetic Amorphous Alloy

In this work, the thermal behavior, soft magnetic properties, and structure of Fe86-xP11C2B1Wx (x = 0, 0.1, 0.2, 0.4, 0.6, 0.8, 1, 2, and 4) amorphous alloys were researched by several experimental methods and ab initio molecular dynamics. The addition of W improved the thermal stability of the alloy system when the first onset crystallization temperature (Tx1) increased from 655 K to 711 K, significantly reduced the coercivity Hc, and decreased the saturation magnetization Bs. The Fe85.6P11C2B1W0.4 alloy showed optimal soft magnetic performance, with low Hc of 1.4 A/m and relatively good Bs of 1.52 T. The simulation results suggested that W atoms increased the distance of the neighboring Fe-Fe pair, reduced the coordination number, narrowed the gap between the spin-up and spin-down electrons of each atom, and decreased the average magnetic moment of the Fe atoms. This work demonstrates a micro-alloying strategy to greatly reduce Hc while maintaining high Bs.

Confocal scanning laser microscopy investigation of crystallization behavior of hot blast furnace slag

The isothermal and non-isothermal crystallization behavior of blast furnace (BF) slag with varying CaO/SiO2 ratios was in-situ observed through a confocal scanning laser microscopy (CLSM). The crystallization kinetics was analyzed and precipitation of crystalline phases was discussed by theoretical analysis from FactSage 8.0 and X-ray Diffraction (XRD). The results showed that, with the increasing CaO/SiO2 ratio from 1.0 to 1.3, the crystals morphology changed first from rectangles and squares to small-size and irregular, and further to long strip shape at the cooling rate of 100 °C/min. The onset crystallization temperature in CTT diagram was higher at a larger CaO/SiO2 ratio due to the decrease of polymerization degree of the slag. For the isothermal crystallization process at 1250°C, the crystals morphology changed gradually from lamellar to long-trip or columnar, and the incubation period in TTT diagram became shorter with the increase of CaO/SiO2 ratio. Avrami index n decreased from appropriately 2.3 to 1.5, and the growth mode of crystals converted from two-dimensional to one- dimensional. XRD analysis showed that only merwinite existed in four slags at 1380°C. Akermanite and gehlenite were generated at 1350°C, and their amount first increased greatly and then decreased slightly with a continuous increase of CaO/SiO2 ratio. At the low temperature, the number of akermanite and gehlenite reduced, while that of merwinite increased obviously in the slags when CaO/SiO2 ratio was 1.2 and 1.3, indicating that increasing CaO/SiO2 ratio promoted the generation of merwinite.

Thermal stability and glass transition kinetics in GeTeSb glasses by using non-isothermal measurement

In this paper we have analysed the thermal properties of three different compositions of chalcogenide glasses Ge15Te85-xSbx (x=0.5, 1, 1.5). The samples have been prepared using the melt quenching technique and the characterisation is done using X-ray diffraction. The compositional dependence on properties were studied using Differential Scanning Calorimetry (DSC) analysis using non-isothermal measurement. The glassy sample crystallized by two transition temperatures Tg1 and Tg2.The dependence of glass transition temperature on heating rate has been studied by Lasocka empirical relation and the Kissinger equation. As a result, the apparent activation energy for glass transition has been determined. Thermal stability has also been determined from the temperature difference between the onset crystallization and glass transition temperature.

Optical, mechanical and thermal properties in HfO2-doped TiO2-LaO3/2 glasses fabricated by aerodynamic levitation

70.21TiO2-(29.79-x)LaO3/2-xHfO2 (x=0, 1.5, 3, 4.5, 6) glasses were fabricated by aerodynamic levitation technique. XRD shows the amorphous state of these synthesized glasses. DSC indicates that the glass transition temperature (Tg) and onset crystallization temperature (Tx) decreases while ΔT (=Tx - Tg) decreases and then increases with the increase of HfO2. Density increases from 4.931 to 5.147 gcm−3 with the addition of HfO2, while hardness increases from 8.587 to 9.058 GPa. Raman spectra indicate that the maximum phonon energy is 720 cm−1. The transmittance region of glasses is wide from 386nm to 6.5 μm, and the largest transmittance can reach 72%. Furthermore, Abbe number decreases from 17.797 to 16.969 with the addition of HfO2, which is attributed to the increase in the inherent absorption wavelength (λ0). Finally, the refractive index increases from 2.293 to 2.324 with the addition of HfO2, which is attributed to the increase in oxygen packing density (OPD), decrease in molar volume (Vm). The reason for the relatively small increase in the refractive index is that the oxygen polarizability has a certain decrease, which offsets a part of the effects of Vm and OPD. These results are useful for designing new optical glass with excellent properties.

High throughput fabrication of zirconium titanate nanofibers by using alternating field electrospinning

Nanofibrous zirconium titanate (Zr0.5Ti0.5O2) was derived from precursor fibers spun with a high-yield, free-surface alternating force electrospinning (AFES). A process productivity of 8.7 g/h was achived in terms of the mass of crystallized Zr0.5Ti0.5O2 nanofibers. The average fiber diameters varied from 185 to 380 nm, depending on the annealing temperature and precursor composition. The onset crystallization temperature of the nanofibers was observed at ∼ 640 °C irrespective to the alkoxide/polymer ratio in precursor fibers, heating rate, and fiber diameter. Nanofibrous Zr0.5Ti0.5O2 maintained its nanocrystallinity, phase stability, and fiber integrity between 600 and 1200 °C. The results demonstrate strong potential of AFES for scalable production of nanofibrous zirconium titanate for demanding applications.

Experimental investigation of minor Si addition on AlNiYCo multi-principal element alloy: Microstructural characterization, thermal stability and corrosion resistance

High-performance multi-principal element alloys are regarded as novel structural and functional materials and also have attracted extensive research interests in academia as well as industry. In order to develop outstanding anti-corrosion and high-microhardness multi-principal element alloys with superior thermal stability, on the basis of our previous study, the effects of minor Si addition on the microstructure, thermal stability and corrosion resistance of (Al1/3Ni1/3Y1/3)92Co8 multi-principal element alloy were investigated in this current research. It was revealed that all types of as-quenched Si-containing alloy ribbons prepared by melt-spinning method could remain the homogeneous amorphous structures and their crystallization onset temperatures were over 760 K at the heating rate of 20 K/min. The average microhardness value of each specimen was more than 498 HV0.1 as well. The average roughness and the root mean square roughness of these studied metallic ribbons exhibited a roughness of 0.20 nm and 0.27 nm or below. When the Si content elevated from 0.5 to 4 at.%, it gave rise to a increase of pitting potential from −0.222 VSCE of the (Al1/3Ni1/3Y1/3)91.5Co8Si0.5 to −0.207 VSCE of the (Al1/3Ni1/3Y1/3)89Co8Si3 and -0.205 VSCE of the (Al1/3Ni1/3Y1/3)88Co20Si4 glassy alloy ribbons, which can be comparable to that of Al86Ni7Y4.5Co1La1.5 metallic glass ribbons by and large. The alloy ribbons with 3 at.% Si exhibited the outstanding anti-corrosion property in 3.5 wt% NaCl solution since it owned the most positive pitting corrosion potential and the widest overpotential region simultaneously compared with the other alloy ribbons. Therefore, it is supposed that adding minor Si element into (Al1/3Ni1/3Y1/3)92Co8 alloy can promote the ability for resisting pitting corrosion. This research work not only further verifies the available formation of amorphous state by minor Si addition, but also sheds light on the role of Si on thermal stability and anti-corrosion performance of AlNiYCo multi-principal element alloy.

Broadband NIR radiative transitions in Er3+/Tm3+ co-doping tellurite glass material

The radiative property of Er3+/Tm3+ co-doping tellurite glass containing metallic silver nanoparticles (Ag NPs) in near-infrared (NIR) band region was studied under the 808 nm pumping. The tellurite glass was prepared by applying melt-quenching and heat-treated technique, and characterized by measuring differential scanning calorimeter (DSC) curve, transmission electron microscopy (TEM) image, absorption spectrum and fluorescence spectrum. Under the optimized combination of Er3+ and Tm3+ ions, a flat and wide NIR band fluorescence in spectral range of 1350 to 1650 nm with full width at half maximum (FWHM) of 161 nm, originating from Er3+:4I13/2→4I15/2 radiative transition (1.53 µm) and Tm3+:3H4→3F4 radiative transition (1.47 µm), was observed in the studied tellurite glass. The fluorescence intensity was increased by about 91% when the Ag NPs with size of ∼17.4 nm was embedded into the doping glass. A similar wide optical amplification spectrum was also observed through the theoretical simulation of stimulated radiative transition of tellurite glass fiber co-doped with Er3+/Tm3+ ions, indicating the potential of Er3+/Tm3+ co-doping tellurite glass applied for broadband fiber amplifiers and tunable lasers. Additionally, the DSC curve revealed the excellent thermal stability of glass host with transition temperature of 381°C and the difference between crystallization onset temperature and transition temperature of 141°C. Some important spectral parameters like radiative transition probability and fluorescence branching ratio among different levels were determined according to Judd-Ofelt theory to better understand the observed broadband and flat NIR luminescence phenomenon.

Discovery of a new criterion for predicting glass-forming ability based on symbolic regression and artificial neural network

Metallic glasses (MGs) are widely used in various fields due to their superior physical properties. Glass-forming ability (GFA) represents the difficulty of forming MGs. Therefore, understanding and establishing the connection between materials characteristics and GFA is a great challenge in MGs research. In this work, to generate a new criterion to characterize GFA, symbolic regression and artificial neural network (ANN) were employed built on 7795 pieces of data. A completely new criterion was proposed and revealed the relationship between three characteristic temperatures (wherein Tg is the glass transition temperature, Tx is the onset crystallization temperature, and Tl is the liquidus temperature) and GFA. The new criterion not only exhibits a higher correlation to the critical casting diameter (Dmax) than the other 11 reported criteria but also illustrates the importance of high power (Tx − Tg)/(Tl − Tx) in characterizing GFA. Moreover, to test the criterion on unreported data, three models that can, respectively, perform GFA classification, predict Dmax, and three characteristic temperatures were built through artificial neural networks. Then, 439 new data generated by the ANN model were generated by models applied on Zr–Co–Al–X (X = W, Si, and Ni) alloys. On the testing data, the new criterion shows stronger generalization than other criteria, which proves its reliability and effectiveness.