High Glass-forming Ability Research Articles

Impact of Intermolecular Interactions, Dimeric Structures on the Glass Forming Ability of Naproxen, and a Series of Its Derivatives.

In this article, thermal properties, molecular dynamics, crystallization kinetics, and intermolecular interactions in pure naproxen (NAP), its amide (NH2-NAP), and four esters (methyl, Met-NAP; isopropyl, Iso-NAP; hexyl, Hex-NAP; and benzyl, Ben-NAP) have been investigated using differential scanning calorimetry as well as broadband dielectric and Fourier transform infrared spectroscopies. We found that the modification of the NAP molecule by substituting a hydrogen atom from the hydroxyl group strongly inhibits the crystallization tendency of this active pharmaceutical ingredient (API) and simultaneously increases its glass forming ability (GFA). In this context, it is worthwhile to stress that pure naproxen and its amide crystallized very quickly, regardless of the cooling rate. Therefore, these compounds cannot be classified as good glass-formers. On the other hand, ester derivatives of API can be easily vitrified. Moreover, dielectric measurements revealed that with an increasing molecular weight of the substituent, the rate of crystallization process slows down significantly. Consequently, Ben-NAP was characterized by the highest GFA among all investigated API esters. Comprehensive FTIR studies clearly indicated that the strong tendency to create dimeric structures in the nonmodified NAP and NH2-NAP is responsible for their enhanced crystallization. At the first sight, our results stay in contrast to most literature data, showing that H-bonds favor the glass formation ability. However, this effect is usually observed for the materials, which form extensive multidirectional hydrogen bonds and associates. In NAP and NH2-NAP, the situation is much different, since both compounds exist mainly as dimers. Therefore, one can postulate that specific intermolecular interactions are an important parameter determining the GFA of different materials, including APIs.

Zr-Co(Cu)-Al bulk metallic glasses with optimal glass-forming ability and their compressive properties

Abstract The formation of bulk metallic glasses (BMGs) in the ternary Zr56Co28Al16 and quaternary Zr56Co28–xCuxAl16 (x=2, 4, 5, 6, 7, mole fraction, %) glassy alloys was investigated via the copper mold suction casting method. The main purpose of this work was to locate the optimal BMG-forming composition for the quaternary ZrCo(Cu)Al alloys and to improve the plasticity of the parent alloy. The X-ray diffractometry (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) were used to investigate the glassy alloys structure and their glass forming ability (GFA). In addition, the compression test, microhardness, nano-indentation and scanning electron microscopy (SEM) were utilized to discuss the possible mechanisms involved in the enhanced plasticity achievement. The highest GFA among Cu-containing alloys was found for the Zr56Co22Cu6Al16 alloy, which was similar to that of the base alloy. Furthermore, the plasticity of the base alloy increased significantly from 3.3% to 6% for the Zr56Co22Cu6Al16 BMG. The variations in the plasticity and GFA of the alloys were discussed by considering the positive heat of mixing within Cu and Co elements.

Development of Ternary Fe-B-C and Quaternary Fe-B-C-Si Amorphous Alloys with High Glass-Forming Ability and High Magnetization

Development of Ternary Fe-B-C and Quaternary Fe-B-C-Si Amorphous Alloys with High Glass-Forming Ability and High Magnetization

Highly Ductile and Ultra-Thick P-Doped FeSiB Amorphous Alloys with Excellent Soft Magnetic Properties.

Herein, we demonstrate the successful synthesis of novel Fe80Si9B(11−x)Px (x = 0, 1, 3, 5, 7) ultra-thick amorphous ribbons by planar flow casting. The influence of P alloying on glass forming ability (GFA), microstructure, thermal stability, soft magnetic properties, and ductility has been systematically investigated. The results reveal that introduction of P into Fe80Si9B11 alloy can remarkably enhance the GFA and increase critical thickness (tc) of the alloy from 45 to 89 um. Furthermore, the annealed FeSiBP amorphous alloys exhibited excellent soft magnetic properties, including high saturation magnetic flux density of 1.54 T, the low coercivity of 1.5 A/m, and low core losses of 0.15 W/kg. In addition, the representative Fe80Si9B8P3 ultra-thick amorphous alloy demonstrate excellent ductility even after annealing at 400 °C for 10 min, which indicates the superior performance of P-doped FeSiB alloys as compared to the commercial Fe78Si9B13 (Metglas 2605 S2) alloy. The combination of high GFA, excellent ductility, and low core losses of newly developed FeSiBP amorphous soft magnetic alloys makes them attractive candidates for magnetic applications in the high-frequency and high-speed electric devices.

The role of open spaces to glass-forming ability in bulk metallic glasses

Element-specific positron annihilation spectroscopy for Fe-B-Y-Nb bulk metallic glasses (BMGs) successfully sheds light on the role of interstitial open spaces in the amorphous matrix, as e.g., geometrically ideal open space, referred to as a Bernal hole, and large-scale nanovoids to glass-forming ability (GFA), yielding the following rules. Applying main constituent atoms in smaller sizes such as Fe, the Bernal holes get small without enhancing GFA since other elements cannot diffuse therein. On the contrary, main constituent atoms in larger sizes such as Ce form the large Bernal holes, which are feasible to accept other elements thus being responsible for GFA. The present findings is of pivotal importance in designing excellent BMGs with high GFA from the viewpoint of elemental combination of materials.

Polarizability, optical basicity and optical properties of SiO2B2O3Bi2O3TeO2 glass system

Glasses having a composition xSiO2xB2O3 (95−2x) Bi2O35TeO2 where x = (5, 10, 15, 20, 25) prepared by the melt-quenching technique. Thermal stability, density, optical transmittance, and the refractive index of these glasses investigated. Glass samples were transparent in the visible to near-infrared (NIR) region and had a high refractive index. A number of glass samples have high glass-forming ability. This indicates that the quarterly glasses are suitable for optical applications in the visible to the NIR region. Bi2O3 substituted by B2O3 and SiO2 on optical properties discussed. It suggested that the substitution of Bi2O3 increased the density, molar volume, the molar polarizability, optical basicity and refractive index in addition to, the oxygen packing density, the optical energy gap, and metallization decrease. These results are helpful for designing new optical glasses controlled to have a higher refractive index. All studied glass presented high nonlinearities, and the addition of network modifiers made a little contribution. Results clarified the bandgap energy reduction, which associated with the growth within the non-bridging oxygen content with the addition of the network modifier. An increase in the refractive index nonlinearity explained by the optical basicity and the high electronic polarizability of the modifier ions.

Kinetics of Glass Transition and Crystallization of a Zr40Hf10Ti4Y1Al10Cu25Ni7Co2Fe1 Bulk Metallic Glass with High Mixing Entropy

The kinetics of glass transition and crystallization of a novel Zr40Hf10Ti4Y1Al10Cu25Ni7Co2Fe1 bulk metallic glass (BMG) with high mixing entropy have been studied by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The continuous DSC curves show five stages of crystallization at lower heating rates (≤ 20 K/min). The activation energies of glass transition were determined by Moynihan and Kissinger methods, while the activation energies of crystallization were calculated utilizing Kissinger, Ozawa, and Boswell models. The crystalline phases corresponding to each crystallization step have been found out. The kinetic fragility of Zr40Hf10Ti4Y1Al10Cu25Ni7Co2Fe1 BMG has also been evaluated. Based on the isothermal DSC curves, the Avrami exponent, evaluated from the Johnson–Mehl–Avrami equation, has been analyzed in detail. The current study reveals that the crystallization behavior of Zr40Hf10Ti4Y1Al10Cu25Ni7Co2Fe1 BMG exhibits characteristics of both the high entropy BMGs and traditional BMGs with a single principal element, leading to its high glass-forming ability.

Formation and properties of Fe25Co25Ni25(P, C, B, Si)25 high-entropy bulk metallic glasses

New ferromagnetic high-entropy bulk metallic glasses (HE-BMGs) with superior glass-forming ability (GFA) and high strength were developed in the pseudo quaternary FeCoNi(P, C, B, Si) system. The HE-BMG rods were fabricated by copper mold casting method in the composition range of Fe25Co25Ni25(P0.3–0.5C0.1–0.3B0.2–0.3Si0.1–0.3)25, in which the Fe25Co25Ni25(P0.4C0.2B0.2Si0.2)25 and Fe25Co25Ni25(P0.5C0.1B0.2Si0.2)25 alloys possess the largest critical diameter of 2.0 mm. The HE-BMGs exhibit excellent soft magnetic and mechanical properties, i.e., low coercivity of 0.8–2.1 A/m, high saturation magnetization of 0.80–0.86 T, high compressive yield strength of 2970–3076 MPa, and large plastic strain of 1.9–2.1%. The mechanisms of the high GFA and good magnetic softness of the alloys were discussed.

A Centimeter-Size High Toughness Zr-Cu-Al-Nb Bulk Metallic Glass with Nano-Crystallization and Phase Separation

In this paper, a centimeter-size Zr-Cu-Al-Nb bulk metallic glass (BMG) with high notch toughness of 107±13 MPa∙m0.5 was designed and fabricated by copper mold casting. With 1% Nb substitution for Zr in Zr48Cu45Al7 glass forming alloy, the glass forming ability (GFA) and toughness of the BMG were enhanced significantly. The coexistence of nano-crystallization and phase separation in the glassy matrix was observed in Zr47Cu45Al7Nb1, which would possibly lead to the high toughness of this alloy due to the easy and populous nucleation of shear bands and the increasing resistance of shear band propagation. The influences of nano-crystallization and phase separation on the toughness of BMGs are discussed in detail. The strategy utilized in this study provides a novel approach in search for new BMGs with high toughness and good GFA.

Characterization, thermodynamic analysis and magnetic investigation of new soft magnetic amorphous/nanocrystalline Co50Fe21Ti19Ta5B5 powders produced by mechanical alloying

In this work, the microstructure, thermal stability and magnetic properties of a new Co50Fe21Ti19Ta5B5 alloy prepared by mechanical alloying (MA) were investigated. Quantitative X-ray diffraction (XRD) analysis performed via Rietveld refinement demonstrated a high glass-forming ability (GFA) of this alloy through a fast amorphization with a glass fraction of about 98 wt% after 20 h milling. In addition, a large driving force for amorphization in Co50Fe21Ti19Ta5B5 alloy was indicated via a great difference between the Gibbs free energy changes for amorphization (−68 kJ/mol) and solid-solution formation (−6 kJ/mol), calculated based on the extended Miedema's semi-empirical model. Thermal analysis confirmed a higher crystallization temperature of new alloy compared to some of mechanically alloyed Co-based glassy powders, recently produced. The presence of few remained nanocrystals with an average size of 5 nm and little un-dissolved boron nanoparticles inside the amorphous matrix were confirmed by high-resolution transmission electron microscopy (HRTEM) measurements. The magnetic measurements revealed that the powders after an optimized milling time and annealing condition show a promising magnetic softness. The new powders exhibited a larger saturation magnetization (78 Am2/kg) and significantly a lower coercivity (0.2 kA/m) with respect to the most of the Co-based amorphous powders prepared by MA.

Electronic structure and glass forming ability in early and late transition metal alloys

A correlation between the change in magnetic susceptibility (Δχexp) upon crystallisation of Cu–Zr and Hf metallic glasses (MG) with their glass forming ability (GFA) observed recently, is found to apply to Cu–Ti and Zr–Ni alloys, too. In particular, small Δχexp, which reflects similar electronic structures, ES, of glassy and corresponding crystalline alloys, corresponds to high GFA. Here, we studied Δχexp for five Cu–Ti and four Cu–Zr and Ni–Zr MGs. The fully crystalline final state of all alloys was verified from X-ray diffraction patterns. The variation of GFA with composition in Cu–Ti, Cu–Zr and Cu–Hf MGs was established from the variation of the corresponding critical casting thickness, dc. Due to the absence of data for dc in Ni–Zr MGs their GFA was described using empirical criteria, such as the reduced glass transition temperature. A very good correlation between Δχexp and dc (and/or other criteria for GFA) was observed for all alloys studied. The correlation between the ES and GFA showed up best for Cu–Zr and NiZr2 alloys where direct data for the change in ES (ΔES) upon crystallisation are available. The applicability of the Δχexp (ΔES) criterion for high GFA (which provides a simple way to select the compositions with high GFA) to other metal-metal MGs (including ternary and multicomponent bulk MGs) is briefly discussed.

Effect of Fe substitution on magnetocaloric effects and glass-forming ability in Gd-based metallic glasses

In this work, we report on the systematic variation of the glass-forming ability (GFA) and magnetocaloric effect (MCE) in Gd55Co20-xAl24Si1Fex (x = 0, 1, 2, 3, 4 and 5 at%) metallic glasses (MGs), which are potential candidates for magnetocaloric cooling applications. The addition of Fe broadens the full width of half maximum of magnetic entropy change (δTFWHM), thereby greatly increases the refrigeration capacity (RC). Accordingly, the δTFWHM as large as 118 K, magnetic entropy change |ΔSM| of 7.26 J kg−1K−1 at 130 K, and corresponding large RC of 857 J kg−1 under applied field of 5 T are obtained for the composition with 5 at% Fe substitution. By increasing the atomic fraction of Fe dopants, the Curie temperature TC increases systematically at the same time. Such high GFA of novel Gd-based MGs with large MCE makes them attractive candidates for magnetic refrigeration applications in the future.

Influence of Ag replacement on supercooled liquid region and icosahedral phase precipitation of Zr65Al7.5Ni10Cu17.5-xAgx (x = 0–17.5 at%) glassy alloys

The glass transition phenomenon for Zr65Al7.5Ni10Cu17.5-xAgx (x = 5–17.5 at%) glassy alloys was observed in the Ag content range below about 15% and the icosahedral phase precipitated as the heating-induced primary phase in the limited Ag content range. In the higher Ag content range where glass transition is not clearly observed, the primary precipitation phase changed to mixed phases of tetragonal Zr3Ag + tetragonal Zr2Ni + hexagonal Zr4Al3. The good correspondence between the appearance of glass transition and the icosahedral phase precipitation was recognized in the multicomponent glassy alloys containing the immiscible type atomic pairs of Ni-Ag and Cu-Ag. Although neither glass transition nor supercooled liquid region is observed for Zr65Al7.5Ni10Ag17.5 and no icosahedral phase is formed, a modified Zr65Al7.5Ni17.5Ag10 alloy with higher Ni/Ag content ratio exhibits glass transition and supercooled liquid region and the primary precipitates also changes to an icosahedral phase. The good correspondence can be interpreted on the basis of the previous knowledge that the appearance of glass transition and supercooled liquid state originates from icosahedral-like medium range ordered atomic configurations. Besides, the 6%Ag-containing alloy keeps high glass-forming ability which is high enough to form a bulk glassy alloy rod of 6 mm by suction casting. The close correlation between the appearance of glass transition phenomenon and the primary precipitation of icosahedral phase is expected to provide a useful knowledge on the role of icosahedral-like atomic configuration in the achievement of bulk glass-forming ability through the stabilization of supercooled liquid.

Formation of Zr-based bulk metallic glass with large amount of yttrium addition

In this study, we systematically studied the effects of Y addition on the glass forming ability (GFA), thermal stability and mechanical property of Zr56Co28Al16 bulk metallic glass (BMG). The results show that two BMGs, i.e., Zr49Co28Al16Y7 and Zr46Co28Al16Y10 with diameters of at least 14 mm, were successfully prepared by the water quenching method. In addition, fully metallic glass ingot about 25 g can be obtained in the Zr46Co28Al16Y10 alloy by using the conventional arc-melting method. The origin of the high GFA of Zr46Co28Al16Y10 alloy was attributed to the smaller Gibbs free energy difference between the supercooled liquid state and crystalline state of the Zr46Co28Al16Y10 than that of Y-free alloy. On the other hand, the fracture strength of Zr-Co-Al-Y BMGs decreases with the increase of Y content. However, the Zr-Co-Al-Y BMGs containing 0–5 at.% Y still exhibit a high fracture strength of about 1690–1790 MPa. The fracture surface morphology of BMGs with 5–12 at.% Y shows a typical featureless mirror surface, implying the brittle deformation. This Zr-Co-Al-Y quaternary BMG could be regarded as a good candidate for developing a new series of BMGs.

Glass-forming ability, thermal properties, and corrosion resistance of Fe-based (Fe, Ni, Mo, Cr)-P-C-B metallic glasses

Co-addition of appropriate Mo, Cr and Ni in the Fe80P12C4B4 alloy not only enhances the thermal stability of the supercooled liquid and glass-forming ability (GFA) but also reduces the glass transition temperature (Tg) of the Fe-based metallic glass. The Fe55Ni15Cr7Mo3P12C4B4 bulk metallic glass (BMG) exhibits a low Tg of 690K, large supercooled liquid region (ΔTx) of 60K, and high GFA with a critical diameter of 2.5mm. The co-addition of Mo, Cr and Ni remarkably improves the corrosion resistance of the BMGs in 1M HCl and 0.5M H2SO4 solutions, which is superior compared to the SUS316L stainless steel. The alloys also possess high compressive yield strength of ~3.01GPa with distinct plastic strain of ~1.2%. The good combination of low Tg, large ΔTx, high GFA, excellent corrosion resistance and mechanical properties makes the developed (Fe, Ni, Cr, Mo)80P12C4B4 BMGs show great promise as anti-corrosion materials suitable for thermoplastic processing.

Zr-Al-Co-Cu bulk metallic glasses for biomedical devices applications

Toxic element-free Zr-based bulk metallic glasses (BMGs) with a property combination of high glass-forming ability, ultrahigh strength and large room-temperature plasticity are useful as surgical devices materials. In the present work, the critical glass formation size (dmax), thermal glass stability and room-temperature mechanical properties of a series of Zr56.25Al18.75(Co1-xCux)25 (x = 0, 0.125, 0.25, 0.375, 0.5, at.%) alloys have been investigated. The Zr56.25Al18.75Co18.75Cu6.25 (x = 0.25) BMG alloy is found to combine a centimeter scale dmax with ultrahigh strength (σy = 2.05 GPa), high Young's modulus (E = 92.4 GPa) and large room-temperature plasticity (ɛP = 3.5%). Comparison of the property combination of various biomedical Zr-based BMGs suggests that the Zr56.25Al18.75Co18.75Cu6.25 BMG can be a promising surgical devices material. The thermal and mechanical stabilities of these BMG alloys are qualitatively understood with the electron concentration and split d-band electronic structure stabilization mechanisms.

On the high glass-forming ability of Pt-Cu-Ni/Co-P-based liquids

The continuous and isothermal crystallization diagrams of the Pt42.5Cu27Ni9.5P21 and the Pt60Cu16Co2P22 bulk glass forming compositions are determined using calorimetric experiments. In the case of the Pt42.5Cu27Ni9.5P21 bulk metallic glass, the formation of the primary crystalline phase can be prevented by rapid cooling in a conventional DSC. In contrast, for similar cooling conditions, the formation of the primary precipitating compound in Pt60Cu16Co2P22 cannot be prevented in a conventional DSC as also observed in in-situ synchrotron X-ray scattering experiments. This is attributed to a critical overheating, above which remaining structures dissolve, resulting in a drastic increase of the degree of undercooling, similar to what is observed in Zr-based BMGs. Using the classical nucleation theory, the combined thermodynamic and kinetic data are used to model the isothermal crystallization data for Pt42.5Cu27Ni9.5P21, yielding an interfacial energy value of 0.11 J/m2 between the primary nucleating crystal and the liquid. This value is three times higher than the value for good Zr-based glass-formers, suggesting that the interfacial energy plays a pivotal role in the exceptionally high glass-forming ability of Pt-P-based systems and compensates for the fragile liquid behavior and the large driving force for crystallization.

Development and application of Fe-based soft magnetic bulk metallic glassy inductors

The characteristics and application fields of core inductors made of Fe-based glassy alloy powders have been reviewed based on the data of Fe-based bulk metallic glasses developed for the last two decades. Fe-based glassy alloys in Fe-Cr-(B,Si,P,C) and Fe-Cr-Nb-(B,P) systems have been used as core inductors in various electronic-magnetic devices. The commercialization is attributed to a bulk glass-forming ability in conjunction with good soft magnetic properties, high mechanical strength, high corrosion resistance and high thermal stability during annealing at the high temperature near glass transition temperature (Tg). Besides, the possibility whether or not the application can be made even for Fe-based amorphous alloys without glass transition as well as bulk glass-forming ability is also discussed on the basis of fundamental properties for recently developed Fe-Cr-Nb-(B,Si,P) and Fe-Mo-(B,Si,P) amorphous alloys. It is concluded that the success of mass production application to magnetic core inductors is attributed to the utilization of Fe-based glassy type alloys with high glass-forming ability, high degree of magnetic softness (low coercivity, high effective permeability and low core losses), high mechanical strength and high corrosion resistance.

Structural properties and energy analysis of ZrxCu92−xAl8 ternary metallic glasses

In this work, classic molecular dynamics simulations were employed to study ZrxCu92−xAl8 (x=55, 60, 65, and 70) ternary alloys. When Cu atoms were gradually replaced by Zr atoms, the local atomic structural evolution and energy landscape were analyzed. Pair distribution functions were used to characterize the structural features. The results showed that Zr-Al, Zr-Cu and Cu-Al atom pairs showed a strong short range order (SRO) within the first shell and they exhibited a weak sensitivity to atomic concentrations while Zr-Zr and Cu-Cu atom pairs presented a strong sensitivity to atomic concentrations. The analyses of the coordination number and coordination polyhedra indicated that substituting Zr atoms for Cu atoms led to the reduction of high coordination polyhedra and precluded the formation of the icosahedral structure, resulting in a more loosely packed atomic structure of the metallic glass. Finally, the energy landscape revealed that, with the increase of Zr composition and the decrease of Cu composition, the energy distribution of the Zr-centered clusters shifted towards a higher energy significantly and this originated from the increase of the number of Zr-Zr atom pairs and the growth of the Zr-Zr atom pair energy. The simulation results revealed that, from both consideration of the structure and energy distributions, the high Zr content Zr-Cu-Al metallic glasses were composed of more weakly bonded regions and packed more loosely, in line with the experimental results that the high Zr content glassy alloys exhibited high plasticity and low glass-forming ability.

Structural signature in Au-based amorphous alloys

Here we elucidated that the anomalous shoulder at the left side of first main peak in structural factor is resulted from packing of AuAu bonds in the Au55Cu25Si20 amorphous alloy (AA), while the first main peak is largely from contributions of AuAu, AuCu and AuSi bonds. Local atomic packing of this glass is mainly composed of 9, 10 and 11-coordinated polyhedra rather than icosahedral-like clusters, in which the small sized clusters prefer avoiding each other while large ones prefer connecting themselves. This anomalous atomic packing structure limits its glass forming ability (GFA) and results in the anomalous shoulder of the first peak in structural factor. With the replacement of 5 at.% Cu atoms by Ag atoms, the spatial connectivity and the atomic packing density in Au55Cu20Ag5Si20 AA are largely increased, which homogenize atomic structures at least up to the second nearest neighbors and frustrate the geometry of competing crystalline-like nuclei, consequently, enhancing the GFA, as observed in experiments. This work illustrates how the atomic packing in an Au-based glass is altered by element substitution and sheds new insights to understanding of high GFA from the atomic scale and thus developing novel AAs with larger critical sizes.