Good Glass-forming Ability Research Articles

Computational Support to Explore Ternary Solid Dispersions of Challenging Drugs Using Coformer and Hydroxypropyl Cellulose.

A majority of drugs marketed in amorphous formulations have a good glass-forming ability, while compounds less stable in the amorphous state still pose a formulation challenge. This work explores ternary solid dispersions of two model drugs with a polymer (i.e., hydroxypropyl cellulose) and a coformer as stabilizing excipients. The aim was to introduce a computational approach by preselecting additives using solubility parameter intervals (i.e., overlap range of solubility parameter, ORSP) followed by more advanced COSMO-RS theory modeling. Thus, a mapping of calculated mixing enthalpy and melting points is proposed for in silico evaluation prior to hot melt extrusion. Following experimental testing of process feasibility, the selected formulations were tested for their physical stability using conventional bulk analytics and by confocal laser scanning and atomic force microscopy imaging. In line with the in silico screening, dl-malic and l-tartaric acid (20%, w/w) in HPC formulations showed no signs of early drug crystallization after 3 months. However, l-tartaric acid formulations displayed few crystals on the surface, which was likely a humidity-induced surface phenomenon. Although more research is needed, the conclusion is that the proposed computational small-scale extrusion approach of ternary solid dispersion has great potential in the formulation development of challenging drugs.

Thermodynamic stabilities of NdFe3Al2, Nd5Fe17 and μ compounds and evolutions of microstructures and magnetic properties of Nd-Fe-Al alloys with nanocrystallites

In the Nd-Fe-Al ternary system, thermodynamic stabilities of three compounds, NdFe3Al2, Nd5Fe17 and μ, were determined by the equilibrated alloys, indicating that both NdFe3Al2 and μ ternary compounds are metastable phases, while Nd5Fe17 compound is a stable phase. Meantime, the microstructures of five representative as-cast alloy buttons are illustrated, which are consisted of crystalline phases and the complex of nanocrystallites + amorphous matrix (NCAM). The crystalline phases including Nd, Nd3Al, Nd2Fe17-xAlx and Nd6Fe13-xAl1+x as well as the nanocrystallites such as dhcp-Nd, fcc-Nd and Nd6Fe13-xAl1+x embedded in the amorphous matrix were observed. Particularly, it is concluded that the fcc-Nd nanocrystallites may be transformed from the fcc dense packing clusters of the amorphous matrix and/or dhcp-Nd nanocrystallites. The hard magnetic properties of these as-cast alloys can be attributed to NCAM and present a non-strict proportionate effect. The alloy composed of Nd + NCAM, with curie temperature (Tc) 515 K, displays the highest intrinsic coercivity Hci 305 kA/m and remanent magnetization Br 10.8 emu/g. Its good glass-forming ability is presented by the high ratio (Tx/Tm) 0.88 and the small interval (Tm-Tx) 105 K of the crystallization temperature (Tx) with the melting temperature (Tm). Since the present investigation focuses on phase stabilities, microstructural characterizations, magnetic properties and glass-forming ability of the Nd-Fe-Al alloys, the obtained results can provide a better understanding for advancing the design of the Nd-Fe-Al based hard magnets and amorphous materials.

A unique Fe-based soft magnetic alloy and its magnetic softening mechanism

Fe-based amorphous alloys with good glass-forming ability (GFA), superior soft magnetic properties, low cost, and a wide heat treatment window have long been pursued in the field of soft magnetic materials due to their importance for mass production and broad applications. In the present study, by strategically adjusting the composition of a low-cost Fe-Si-B-P-Cu-C alloy, we achieved a saturation magnetization (Ms) of approximately 186 emu/g and a coercivity (Hc) of about 6 A/m for the Fe82.5 alloy with a good GFA. Specifically, the limited Cu content and suitable contents of metalloid elements played pivotal roles in enhancing the nuclei barrier and stabilizing the amorphous matrix. This, in turn, facilitated the formation of a finely uniform nanocrystalline structure dispersed within the amorphous matrix, enhancing soft magnetic properties during annealing. Notably, this magnetic softening behavior occurred at a lower heating rate. Structural characterizations revealed that a transient metalloid-rich shell and a stable amorphous matrix contributed to the slow growth of the α-Fe (Si) during prolonged isothermal annealing. This is in contrast to the agglomeration of small nanograins into larger clusters at high heating rates, which enhances the versatility and potential applicability of the alloy. The successful development of this novel nanocrystalline alloy offers promising guidance for addressing the challenges associated with the mass production of soft magnetic materials.

Exploring new machinable, strong lithium metasilicate-based glass-ceramics for dental applications

This research aimed to create a new Li metasilicate-based glass-ceramic for dental use, prioritizing improved chemical durability (CD) and machinability while preserving good glass-forming ability (GFA) and adequate mechanical properties. Characterization also involved examining fracture strength (Sf) and fracture toughness (KIC). The experimental approach involved precise microstructural adjustments through designed compositional changes and controlled thermal treatments. Four compositions underwent scrutiny using mechanical tests, microscopy, differential scanning calorimetry, and X-ray diffraction to analyze the impact of lithium metasilicate (LS) and disilicate (LS2) crystals on these properties. Machinability was evaluated by weight loss measurements during controlled grinding experiments. The developed GCs exhibited interconnected acicular LS and LS2 crystals, which resulted in favorable Sf ∼300 MPa and KIC ∼1.7 MPa m1/2 (SEVNB). Although the KIC was smaller than that of an experimental LS-LS2 GC (285 MPa and 3 MPa m1/2(double torsion)) used as a reference, the chemical durability (126 μg/cm2 for ML14F GC) improved by nearly 50 % compared to the reference (∼220 μg/cm2). This study introduced three new GCs with LS as the major phase (rather than the traditional LS2), showcasing commendable GFA, chemical durability and machinability, with satisfactory flexural strength and fracture toughness.

Characterization of Drug with Good Glass-Forming Ability Loaded Mesoporous Silica Nanoparticles and Its Impact Toward in vitro and in vivo Studies.

Solid oral dosage forms are mostly preferred in pharmaceutical formulation development due to patient convenience, ease of product handling, high throughput, low manufacturing costs, with good physical and chemical stability. However, 70% of drug candidates have poor water solubility leading to compromised bioavailability. This phenomenon occurs because drug molecules are often absorbed after dissolving in gastrointestinal fluid. To address this limitation, delivery systems designed to improve the pharmacokinetics of drug molecules are needed to allow controlled release and target-specific delivery. Among various strategies, amorphous formulations show significantly high potential, particularly for molecules with solubility-limited dissolution rates. The ease of drug molecules to amorphized is known as their glass-forming ability (GFA). Specifically, drug molecules categorized into class III based on the Taylor classification have a low recrystallization tendency and high GFA after cooling, with substantial "glass stability" when heated. In the last decades, the application of mesoporous silica nanoparticles (MSNs) as drug delivery systems (DDS) has gained significant attention in various investigations and the pharmaceutical industry. This is attributed to the unique physicochemical properties of MSNs, including high loading capacity, recrystallization inhibition, excellent biocompatibility, and easy functionalization. Therefore, this study aimed to discuss the current state of good glass former drug loaded mesoporous silica and shows its impact on the pharmaceutical properties including dissolution and physical stability, along with in vivo study. The results show the importance of determining whether mesoporous structures are needed in amorphous formulations to improve the pharmaceutical properties of drug with a favorable GFA.

Composition Design Strategy for High Entropy Amorphous Alloys.

High entropy amorphous alloys (HEAAs) are materials that have received much attention in recent years. They exhibit many unique properties; however, research on their composition design method has not been deep enough. In this paper, we summarized some effective composition design strategies for HEAAs. By adjusting the atomic ratio from quinary bulk metallic glasses, Ti20Zr20Cu20Ni20Be20 HEAA with a high fracture strength of 2315 MPa was designed. By similar element addition/substitution, a series of Ti-(Zr, Hf, Nb)-Cu-Ni-Be HEAAs was developed. They possess good glass-forming ability with a maximum critical diameter of 30 mm. Combining elements from those ternary/quaternary bulk metallic glasses has also proved to be an effective method for designing new HEAAs. The effect of high entropy on the property of the alloy, possible composition design methods, and potential applications were also discussed. This paper may provide helpful inspiration for future development of HEAAs.

Inverse design machine learning model for metallic glasses with good glass-forming ability and properties

The design of metallic glasses (MGs) with good properties is one of the long-standing bottlenecks in materials science and engineering, which has been relying mostly on far less efficient traditional trial-and-error methods. Even the currently popular machine learning-based forward designs, which use manual input to navigate high dimensional compositional space, often become inefficient with the increasing compositional complexity in MGs. Here, we developed an inverse design machine learning model, leveraging the variational autoencoder (VAE), to directly generate the MGs with good glass-forming ability (GFA). We demonstrate that our VAE with the property prediction model is not only an expressive generative model but also able to do accurate property prediction. Our model allows us to automatically generate novel MG compositions by performing simple operations in the latent space. After randomly generating 3000MG compositions using the model, a detailed analysis of four typical metallic alloys shows that unreported MG compositions with better glass-forming ability can be predicted. Moreover, our model facilitates the use of powerful optimization algorithms to efficiently guide the search for MGs with good GFA in the latent space. We believe that this is an efficient way to discover MGs with excellent properties.

A novel Zr-based Zr47Ti29Ni21V3 amorphous brazing filler metal for high toughness and strength joining of Ti6Al4V alloy

In order to achieve the combination of high impact toughness and strength of brazed titanium alloy joints, a novel Cu-free Zr47Ti29Ni21V3 (at%) alloy with good glass-forming ability was developed and synthesized as a brazing filler metal (BFM) in a ribbon form by melt-spinning. Significantly different from the Ti6Al4V joints obtained by using the conventional Ti–13Zr–21Cu–9Ni BFM, the joint brazed with the present amorphous Zr-based BFM at 1233 K for 30 min consisted of a uniform α-Ti+β-Ti lamellar colony microstructure without a fusion line. The resultant joint exhibited superior impact toughness (∼21.3 J/cm2) and tensile shear strength (∼441 MPa) compared with the joint brazed with the Ti–13Zr–21Cu–9Ni BFM (∼3.4 J/cm2 and ∼292 MPa). The good mechanical properties of the present Ti6Al4V joint are attributed to the formation of the uniform microstructure as well as the reduction of intermetallic compounds in the braze zone by using the novel Zr–Ti–Ni–V amorphous BFM.

Prediction of glass-forming ability based on multi-model fusion

At present, it is difficult to find metals with good glass-forming ability (GFA), seriously hindering the industrial application of metallic glasses (MGs). Therefore, it is urgent to develop a regression model that provides a prompt prediction for the critical diameter (Dmax) of alloys. Most established models rely heavily on elaborate feature descriptors and single algorithms, which may limit the predictive accuracy. In this work, the Stacking fusion is adopted to construct a more efficient model (Stack-Dmax). To avoid domain knowledge involved in feature engineering, only the alloy composition is treated as the input. Experiments revealed that compared to 6 individual models, the Stack-Dmax model is more robust and accurate regarding performance; it achieves improvement up to 41.61 %, 54.76 % and 35.67 % respectively in RMSE, R2 and MAE. The Stack-Dmax model is also better than the five most recently reported models based on RF, XGB, and CNN. In practical applications, our model exhibits potential for designing new La- and Mg-based MGs. These findings suggest that the Stacking approach provides an effective GFA-prediction model only based on the composition of alloys.

Composition design of high Bs Fe-based amorphous powders with good sphericity

Fe83SixByC(17-x-y) has good glass forming ability (GFA), and high saturation magnetic induction (Bs), and spherical amorphous powder can be prepared using a gas–water coupling atomization (GWC) device. Herein, the effects of metalloid elements (B, C, Si and P) on the thermal parameters and magnetic properties of the Fe83SixByC(17-x-y) powder are discussed. The research conclusion shows that the Fe83Si2.5B11.5C3 amorphous powder exhibits the best comprehensive performance. Through the Lorentz microscope pattern of Fe83Si2.5B11.5C3 amorphous powder, magnetic domains walls are observed to gather and interlace in the outer region of the particle. The Fe83Si2.5B11.5C3 amorphous powder exhibits a high initial crystallization temperature (Tx1), followed by a ΔTx of 27 ℃, and then crystallization completion at 561.1 ℃. Some clusters or primary crystals are produced in the amorphous matrix after annealing at 520 ℃ (below Tx1 534 ℃) for 1 h. A further increase in the annealing temperature to 570 ℃ (beyond Te1 561.1 ℃) causes the precipitation of a large amount of crystalline phase α- Fe (Si) and hard magnetic phase Fe2B, thereby resulting in the rapid deterioration of the magnetic properties of the amorphous powder.

Prediction of glass-forming ability in ternary alloys based on machine learning method

In this paper, six machine learning (ML) models including k-nearest neighbour, adaptive boosting, gradient boosting regression tree, extreme gradient boosting tree, support vector regression (SVR) and random forest were built in the frame of ternary alloys to predict the critical size of glass formation (Dmax) based on 840 alloy data. Composition, atomic size difference, enthalpy of mixing, electronegativity difference, and valence electron concentration were selected as input features. The features were selected by Pearson correlation analysis and target value of Dmax was transformed into the logarithmic form. The determination coefficient and root mean square error were used to evaluate the prediction performance of models. The result showed that the SVR model has a good generalization ability. Additionally, the prediction ability of SVR was verified in Zr−Al−Co and La−Al−Co alloy systems. It is thus suggested that ML has great potential in predicting and pinpointing the amorphous composition with good glass-forming ability.

Mechanical properties and non-isothermal crystallization kinetics of novel Ti-based high-entropy bulk metallic glasses

In this work, five novel Ti- and TiZr-based high entropy bulk metallic glasses (HE-BMGs) with good glass forming ability (GFA) were developed, among which the (Ti37.31Zr22.75Be26.39Al4.55Cu9)94Ni6 alloy possesses the largest critical diameter of 9 mm. All developed HE-BMGs exhibit high yield strength and good compressive plasticity at room temperature. Especially, the (Ti37.31Zr22.75Be26.39Al4.55Cu9)94Co6 alloy with large GFA has suitable density and high specific strength (3.90 × 105 N m/kg), showing great potential in the aerospace sector. Moreover, the activation energies at characteristic temperatures of three HE-BMGs were obtained using the Kissinger method. The local Avrami exponents were calculated to analyze the crystallization mechanism of these HE-BMGs, revealing that the first crystallization process is mostly dominated by diffusion-controlled three-dimensional growth of pre-existing nuclei. In addition, all three HE-BMGs can be classified as “intermediate glasses” according to their fragility index values.

Design and investigation of an FeSiBCNb metallic glass with low electrical and thermal conductivity

In this work, a cost-efficient Fe-based metallic glass in the Fe74BxSiyCzNb2 (x + y + z = 24) composition range with low electrical and thermal conductivity is developed. Ingots with different alloy compositions are produced from high-purity Fe, B, Si, C, Nb powders in a tube furnace and processed into metallic ribbons by melt spinning. The high content of various metalloids in the compositions is expected to enhance the electrical resistivity and lower the thermal conductivity in the amorphous phase. The thermophysical properties and the amorphous structure of the ribbon samples are investigated by x-ray diffractometry (XRD), differential scanning calorimetry (DSC), dilatometry (DSD) and high resolution transmission electron microscopy (HRTEM). The investigations confirm that the characteristic temperatures Tg, Tm, Tx and Tl of the alloy and thus its GFA are strongly dependent on the atomic composition. A particularly good glass forming ability (GFA) is achieved with the alloy composition Fe74B8Si12C4Nb2. In addition to that a high hardness of 984 HV0.1 and a thermal conductivity as low as 6.41 W/mK is observed. It is concluded that metallic glasses in the Fe74BxSiyCzNb2 (x + y + z = 24) composition range can be considered as a cost-effective coating material for thermal insulation in a temperature range below Tg ≈ 540 °C, as well as electrical components and wear protection.

Efecto de la sustitución parcial de Cr con Co sobre la capacidad de formación de vidrio, propiedades mecánicas y magnéticas en vidrios metálicos a granel Fe48Mo14Cr15-xCoxB6P8Si7Y2

Fe-based BMGs are well known for its attractive combination of structural, magnetic and corrosion properties. These alloys are widely used in industry because of low price and good glass forming ability (GFA). In this paper, the effect of partial substitution of Cr with Co on GFA, mechanical and magnetic properties of Fe48Mo14Cr15-xCoxB6P8Si7Y2 bulk metallic glasses was studied. The samples were prepared by copper mold casting technique in rod form. The elaborated alloys were structurally investigated by X-Ray diffraction (XRD) and differential scanning calorimetry (DSC), while the mechanical properties were investigated by compressive and nanoindentation tests. Also, the magnetic properties were investigated. The GFA was estimated by several criterion or parameters (reduced transition temperature Trg, ΔTx, α, β, γ and δ parameters). It was found that the addition of Co instead of Cr leads to a slight increase of the glass forming ability of Fe-Mo-Cr-B-P-Si-Y family. Also, an increase in magnetic properties, hardness, elastic modulus and compressive strength has been noted.

Enhancing glass forming ability and magnetic properties of Co–Fe–Si–B metallic glasses by similar element substitution: Experimental and theoretical investigations

The poor glass forming ability (GFA) and magnetic properties of Co-based metallic glasses limit their applications. Herein the effects of similar element substitution of Co by Fe on the GFA and magnetic properties of Co72.5-xFexSi12.5B15 (x = 0, 4.5, 20, and 36) amorphous alloys were studied by experiments and density functional theory (DFT) calculations. The experimental results indicate that Fe substitution for Co improves the GFA of the studied metallic glasses, but in a concentration dependent manner, where Co52.5Fe20Si12.5B15 shows the best GFA. Meanwhile, the saturated mass magnetization (Ms) enhances with increasing Fe content. The atomic structures were analyzed by pair distribution function, coordination number, chemical short-range order, Voronoi polyhedron, and locally five-fold symmetry, and it was found that the highest average degree of the locally five-fold symmetry in Co52.5Fe20Si12.5B15 is a critical factor for enhancing GFA, which improves the stability of the local atomic structures by increasing the packing density and reducing the potential energy. Density of states and magnetic moments calculated for the four metallic glasses manifest that the larger magnetic moment of Fe atoms and gradual increase in the contribution of the Fe 3d state are responsible for the increase in the Ms with Fe content. This work links the GFA and magnetic properties of Co–Fe–Si–B metallic glasses with their atomic/electronic structures, providing reference for designing Co-based metallic glasses with good GFA and enhanced magnetism.

Even partially amorphous Pd2Ni2P metallic glass significantly promotes hydrogen evolution electrocatalysis

Metallic glasses are expected to be endowed with higher electrocatalytic activity, with respect to their crystalline counterparts, due to the presence of a high density of under-coordinated sites. However, glasses made of metals, as opposed to metal oxide/sulfides are harder to synthesize, with the challenge increasing with amorphousness. In light of these issues, we calibrate the increase in hydrogen evolution reactivity using the Pd2Ni2P bulk metallic glass composition as a model system. This composition has a good glass-forming ability and is interesting from a catalytic point of view, as Ni and P lie on the opposite leg of the HER volcano plot with respect to Pd. Partially amorphous (PA) Pd2Ni2P alloy displayed a five-fold higher specific electrocatalytic activity on per unit electrochemical surface area (ECSA) basis compared to its crystalline (C) counterpart. This magnitude of specific electrocatalytic activity, which is on par with that for pure Pd, has been achieved with just 40% of the precious metal, leading to a considerable saving in cost. The homogeneous single-phase structure of the highly electro-active partially amorphous alloy leads to higher electrochemical stability than its polycrystalline counterpart. This finding implies that many compositions ignored traditionally due to their poor electrocatalytic activity or stability can now be reconsidered in amorphous forms, thus expanding the material space of valuable catalysts.

Nanocomposite (S3Sb2) x (S2Ge)100−x chalcogenide glasses: structural and physical properties

The current paper shows the different effects of the incorporation of sulfur (S)–antimony (Sb) on both the structural and physical properties of nanocomposite (S3Sb2) x (S2Ge)100−x chalcogenide glass for x = 15, 30, 45 and 60. Different physical parameters such as lone-pair electrons, average coordination number, interatomic spacing and field of strength increase with the addition of antimony–sulfur, while other parameters such as heat of atomization and polaron radius show the reverse behavior. The stoichiometry (R > 1) shows that the studied compounds are rich in chalcogen atoms, and an increase in lone-pair electrons indicates the good glass-forming ability of the studied compound.

API solubility in semi-crystalline polymer: Kinetic and thermodynamic phase behavior of PVA-based solid dispersions

The formulation of amorphous solid dispersions (ASDs) represents a promising strategy for improving the poor bioavailability of many active pharmaceutical ingredients (APIs). The objective of this study was to investigate and compare the long-term physical stability (LTPS) of polyvinyl alcohol (PVA)-based solid dispersions formulated via hot-melt extrusion (HME) with their respective API–PVA temperature–composition (T–C) phase diagram. Furthermore, the impact of API glass-forming ability (GFA) on the LTPS was evaluated through the selection of two APIs with contrasting GFA (i.e., indomethacin (IND; good GFA) and naproxen (NAP; poor GFA)). Even though the predicted solubility of both APIs in PVA was less than 1 wt% at T = 25 °C, IND remained fully amorphous in HME-formulated IND–PVA extrudates with initial API loadings of 50, 40, and 30 wt% after a 24-month storage period. Meanwhile, NAP recrystallized to a considerable degree in each analogous sample with an amorphous NAP content of 22.5–23.5 wt% remaining after a 12-month storage period. While the constructed T–C phase diagrams were still in agreement with their respective LTPS study, they did not account for the impact of water uptake as well as potential HME-induced effects on the extrudate glass-transition temperature. This work may serve as a useful reference point for researchers who are interested in determining the solubility of an API in a semi-crystalline polymer and the challenges therein.

Exploring the utility of co-amorphous materials to concurrently improve the solubility and permeability of Fexofenadine

In this study, the co-amorphous materials of BCS class-IV drug Fexofenadine were prepared by employing Naringin as a co-former. Naringin was employed as a coformer anticipating the concurrent improvement in the solubility and permeability by virtue of its good glass-forming ability and p-gp inhibition potential, respectively. The solid-state characterization of prepared co-amorphous materials by powder-XRD, DSC, and FTIR revealed amorphous state and π-π interactions between Fexofenadine and Naringin. The interactions were confirmed by Molecular Dynamic studies employing Schrodinger material science Suite®. The co-amorphous materials demonstrated improved solubility and dissolution for both Fexofenadine and Naringin. The deliquescent nature of Naringin led to the significant moisture uptake by coamorphous materials. However, the dissolution advantage of Fexofenadine and Naringin sustained in the stability samples due to accelerated π-π interactions in the presence of water. The permeability of co-amorphous samples was estimated using everted gut sac method which was found improved by 5-fold and 3.5-fold for Fexofenadine and Naringin, respectively. The improvement in the permeability was attributed to the interplay between solubility improvement and dose-dependent P-gp inhibition by Naringin.

Utilization of high entropy in rare earth-based magnetocaloric metallic glasses

In this study, the magnetic behavior and magnetocaloric effect (MCE) of Dy18Er18Y18Ni26Al20 and Dy13.5Er13.5Y13.5Gd13.5Ni26Al20 high-entropy bulk metallic glasses (BMGs) were systematically investigated, as well as Dy27Er27Ni26Al20 and Dy54Ni26Al20 medium-entropy BMGs. Distinct spin glass-like behavior below the Curie temperature and large MCE at cryogenic temperature were observed in all BMGs. Competitive magnetic entropy change values of 10.6 and 10.2 J kg−1K−1 were obtained for the Dy27Er27Ni26Al20 and Dy18Er18Y18Ni26Al20 BMGs, respectively, under a magnetic field change of 5 T. Accordingly, the effect of configuration entropy on the magnetic response and MCE was discussed. It was found that the magnetic phase transition temperature, magnetic hysteresis and refrigeration capacity can be altered by utilization of configuration entropy, which can be ascribed to the change in random magnetic anisotropy and magnetic interactions. However, no distinct difference in the magnetic entropy change was observed from the ternary Dy54Ni26Al20 to senary Dy13.5Er13.5Y13.5Gd13.5Ni26Al20 BMGs with increasing configuration entropy. The results reveal that the typical cocktail effect of high-entropy alloys is not applicable to magnetic entropy changes in these BMGs. Nevertheless, all BMGs in this study show good glass-forming ability and MCE which make them promising refrigerant candidates at cryogenic temperatures.