Excellent Glass-forming Ability Research Articles

Medium-range order structure analysis of metallic glasses based on reverse Monte Carlo modeling

The elucidation of amorphous alloy characteristics presents a formidable challenge due to the absence of crystalline arrangements and enigmatic imperfections. This study aimed to tackle this challenge through a comprehensive investigation utilizing synchrotron X-ray diffraction (XRD), extended X-ray absorption fine structure spectroscopy (EXAFS), ab initio molecular dynamics (AIMD) simulations, and reverse Monte Carlo (RMC) modeling. The primary objective was to delve into the medium range order (MRO) structure of metallic glasses (MGs) containing CuXZr100-X, wherein X represents values of 50, 56, 60, and 64. The results obtained from this research demonstrate that an increase in the Cu atom concentration within Cu-Zr MGs leads to the formation of complete icosahedral clusters and high-coordination polyhedral connections, thereby bolstering the stability and heterogeneity of local structures. Examination of the stiff full icosahedral bones shows that defects exist in the network connections on the MRO, resulting in a lack of connectivity in the positive icosahedron. Conversely, the density of defects decreases with an increase in Cu content. The observation suggests that the observed low MRO defects in Cu64Zr36 MGs may be accountable for their excellent glass-forming ability and kinetic stability.

Effect of boron content on microstructure evolution and crystallization behavior of Fe7(CoNi)93-xBx (x=15, 18, 21) eutectic high-entropy alloys

The effect of boron content on microstructure evolution, glass-forming ability and crystallization behavior of Fe7(CoNi)93-xBx (x = 15, 18, 21) eutectic high-entropy alloys (EHEAs) was investigated. Bulk Fe7(CoNi)93-xBx EHEAs and ribbons were prepared by vacuum frequency induction melting furnace and melt-spinning method, respectively. The results show that the microstructure of as-cast hypoeutectic Fe7(CoNi)78B15 alloy consists of primary (Fe, Co, Ni) dendrite and lamellar eutectic. The eutectic Fe7(CoNi)75B18 alloy shows a fully lamellar eutectic structure consisting of (Fe, Co, Ni) phase and B-rich phase. The microstructure of hypereutectic Fe7(CoNi)72B21 alloy exhibits primary B-rich dendrite and lamellar eutectic. The as-spun Fe7(CoNi)75B18 and Fe7(CoNi)72B21 alloys show an amorphous structure. By comparison, the hypereutectic Fe7(CoNi)72B21 alloy shows an excellent glass-forming ability and thermal stability, which is attributed to the increase of crystallization activation energy induced by B addition. In addition, the increase of B addition inhibits the crystallization behavior, which is caused by the formation of stable covalent bonds between boron and other elements. This work provides an alternative route for the preparation of metallic glass by introducing the non-metallic boron component.

Advancing Bulk Metallic Glass Formation: Utilizing Rare-Earth Elements in Zr-Based Alloys

Zr-based bulk metallic glasses (BMGs) are characterized by excellent glass-forming ability, combined with superior mechanical properties. However, oxygen impurities degrade both these aspects as oxides serve as heterogeneous nucleation sites during solidification. Rare-earth elements (REEs) are known to be good oxygen scavengers, binding oxygen to less harmful forms. The most stable rare-earth oxide (REO) is M2O3, which occurs in three polymorphic forms, depending on the radius of metal cation: cubic, hexagonal, and monoclinic. Here, we show the effect of Sc, Y, Lu, Nd, and Gd additions in relation to the oxygen content on the glass-forming ability of the Zr52.5Cu17.9Ni14.6Al10Ti5 alloy. Microscopic observations (SEM) supported by chemical analysis (EDS, WDS), structure identification (XRD), and thermal analysis (DTA) were carried out. The critical diameter for glass formation (Dc) in the high oxygen alloy doped with cubic oxide-forming elements (Sc, Y, and Lu) can be even higher (Dc = 9 mm) compared to the undoped alloy synthesized from low oxygen components. Therefore, we have demonstrated that it is feasible to produce BMG using low-purity constituents with REE-based oxygen scavengers. This bridges the gap between laboratory development and cost-effective commercial applications.Graphical

Connecting the composition, structure, and magnetic property in high-entropy metallic glasses

High-entropy metallic glasses (HE-MGs) are a new class of materials with unique properties that often exceed both those of crystalline high-entropy alloys and single-principal-element metallic glasses. In recent years, soft magnetic HE-MGs have shown excellent glass-forming ability and superb magnetic softness, thus exhibiting promising prospects. However, the lack of a sufficient understanding of composition-structure-property relationships is a major challenge for the development of HE-MGs. Here, we propose the "framework + fluctuation" model based on the Bethe-Slater (BS) curve. The model shows that in HE-MGs, metalloids will change the distribution of ferromagnetic metal atoms in the short-range (interatomic) length scale, thus affecting Curie temperature (TC) and saturation magnetic flux density (Bs) of HE-MGs. The model explains the dramatic variation of Bs caused by changing the ratio of metalloids in HE-MGs with a fixed content of ferromagnetic metal elements. The structural changes predicted by the model were further confirmed by ab initio molecular dynamics simulations. Besides providing a theoretical explanation, the model also quantitatively characterizes the effects of different metalloids on both structure and magnetic properties. The model sheds light on the role of the short-range distribution of ferromagnetic metal elements on ferromagnetism in HE-MGs, providing insights into the development of high-performance soft magnetic HE-MGs.

Biomolecular glass with amino acid and peptide nanoarchitectonics

Glass is ubiquitous in life and widely used in various fields. However, there is an urgent need to develop biodegradable and biorecyclable glasses that have a minimal environmental footprint toward a sustainable society and a circular materials economy. Here, we report a family of eco-friendly glasses of biological origin fabricated using biologically derived amino acids or peptides through the classic heating-quenching procedure. Amino acids and peptides with chemical modification at their ends are found able to form a supercooled liquid before decomposition and eventually glass upon quenching. These developed glasses exhibit excellent glass-forming ability and optical characteristics and are amenable to three-dimensional-printed additive manufacturing and mold casting. Crucially, the glasses show biocompatibility, biodegradability, and biorecyclability beyond the currently used commercial glasses and plastic materials.

Magnetic properties and magnetocaloric effect (MCE) in the melt-spun Tm20Ho20Gd20Ni20Al20 amorphous ribbon

We fabricated the Tm20Ho20Gd20Ni20Al20 ribbons by melt-spun technology and determined its glass forming ability (GFA), magnetic properties, magnetic phase transition (MPT) character, and magnetocaloric performance. The Tm20Ho20Gd20Ni20Al20 melt-spun ribbon exhibits fully amorphous nature and excellent GFA. A second order (SO) type MPT from ferromagnetic to paramagnetic was observed around the Curie temperature of 30.3 K. Moreover, considerable MCE and magnetocaloric performance in Tm20Ho20Gd20Ni20Al20 amorphous ribbon were realized with the maximum magnetic entropy change, temperature-averaged entropy change of 10 K lift, and relative cooling powder/refrigerant capacity of 9.4 J/kgK, 9.0 J/kgK, and 527.2/422.1 J/kg under 0–5 T field change, respectively. These magnetocaloric parameters are close to most of the recently reported magnetocaloric materials, which made the Tm20Ho20Gd20Ni20Al20 amorphous HE ribbon amorphous ribbon also of potential for practical cryogenic MR applications.

Atomic Structures and Glass-Forming Ability of Pd-Based Bulk Metallic Glasses

To understand the relation of the glass-forming ability (GFA) to the atomic configurations of Pd42.5Ni7.5Cu30P20 (PNCP) metallic glass having the best GFA at present, the local structures were investigated by combining data obtained anomalous x-ray scattering, x-ray and neutron diffraction and applying reverse Monte Carlo modeling. By comparing the results of PNCP with Pd40Ni40P20 and Pd40Cu40P20 having a slightly and much worse GFAs, respectively, characteristic features were observed in the hyper-ordered atomic structures around the secondary metals of Ni and Cu, such as the concentration inhomogeneity, the fraction of pure and slightly distorted icosahedra, and the existence of large persistent homology rings. The structural heterogeneity for the excellent GFA of PNCP would be considered by an incompatible mixture of covalent-like Pd-P configurations and icosahedral clusters around the secondary metals.

Evolutionary design of machine-learning-predicted bulk metallic glasses.

The size of composition space means even coarse grid-based searches for interesting alloys are infeasible unless heavily constrained, which requires prior knowledge and reduces the possibility of making novel discoveries. Genetic algorithms provide a practical alternative to brute-force searching, by rapidly homing in on fruitful regions and discarding others. Here, we apply the genetic operators of competition, recombination, and mutation to a population of trial alloy compositions, with the goal of evolving towards candidates with excellent glass-forming ability, as predicted by an ensemble neural-network model. Optimization focuses on the maximum casting diameter of a fully glassy rod, D max, the width of the supercooled region, ΔT x, and the price-per-kilogramme, to identify commercially viable novel glass-formers. The genetic algorithm is also applied with specific constraints, to identify novel aluminium-based and copper-zirconium-based glass-forming alloys, and to optimize existing zirconium-based alloys.

Relationship between atomic structure and excellent glass forming ability in Pd[formula omitted]Ni[formula omitted]Cu[formula omitted]P[formula omitted] metallic glass

To understand the relation of the glass-forming ability (GFA) to the local atomic configurations of a Pd42.5Ni7.5Cu30P20 (PNCP) metallic glass having the best GFA at present, the local structures were investigated by combining data obtained from anomalous X-ray scattering, X-ray and neutron diffraction, and applying reverse Monte Carlo modeling. By comparing the results of PNCP with Pd40Ni40P20 (PNP) and Pd40Cu40P20 (PCP) having a slightly and much worse GFAs, respectively, characteristic features were observed in the hyper-ordered atomic structures. Firstly, the concentration inhomogeneity of Ni/Cu in PNCP is larger than that of Ni in PNP and Cu in PCP. Secondly, a Voronoi tessellation showed that the fraction of pure icosahedral arrangements around the Cu atoms increases significantly in PNCP by adding icosahedral-preferred Ni atoms in PCP. Finally, a persistent homology (PH) analysis reveals the largest intermediate-size Cu PH rings in PNCP among the PH rings in these Pd-based BMGs. The structural heterogeneity for the excellent GFA of PNCP would be considered by an incompatible mixture of specific Pd-P configurations and icosahedral clusters around the secondary Ni and Cu metals.

The effect of minor alloying on the glass forming ability and crystallization reaction of Ti32.8Zr30.2Cu9M5.3Be22.7 (M=Fe, Co, and Ni) bulk metallic glass

Glass forming ability (GFA) is critically important for large-scale processing and application of bulk metallic glasses (BMGs). It is now widely accepted that the compositions of BMGs with excellent GFA can be located in off-eutectic regions, where the melts have high stability and primary crystallization plays an important role. In this study we reported that the thermodynamic properties of Ti32.8Zr30.2Cu9Fe5.3Be22.7, Ti32.8Zr30.2Cu9Co5.3Be22.7 and Ti32.8Zr30.2Cu9Ni5.3Be22.7 BMGs to understand the origin of the GFA in these glass-forming systems. It is present that these off-eutectic TiZr-based alloys have high thermomechanical stability and the GFA can be improved by manipulating the primary crystallization through minor alloying. The icosahedron-like short-range ordered arrangement improves the stability of the supercooled liquid, and the (Ti, Zr)2M phase with complex structure formed by minor alloying slows down the nucleation and growth of crystal phase, synergistically contributing to better GFA.

Alloy design strategy to improve fluidity of Zr-based bulk metallic glass for near-net-shape manufacturing

The near-net-shape manufacturing via casting has great potential to commercialize bulk metallic glasses (BMGs) for the complex-shaped structural material. However, it is difficult to cast BMGs with the excellent glass-forming ability (GFA) into the precise dimensions of complex shapes, because the slow kinetics of crystallization of the BMG is related to the high viscosity and low fluidity of the melt. In this study, to overcome this limitation, Zr-based BMG with excellent GFA, hardness, and significantly improved fluidity compared to Vitreloy 106 was systematically developed. Utilizing the ZrCuNi liquidus projection, it is possible to design BMG-forming alloy compositions with a low liquidus temperature (TL) by compositional tuning in the ZrCuNiAl quaternary alloy system. We also propose an alloy design methodology that can simultaneously improve the key properties of Zr-based BMGs by minor addition. Interestingly, Ag can be added instead of Zr in ZrCuNiAl alloys, resulting in higher hardness and lowest TL without deterioration of GFA. Thus, the addition of Ag can lead to a significant increase in flow length of about 40% compared to that of Vitreloy 106, because the TL is a dominant factor that determines fluidity under various casting conditions. This study shed light on how to simultaneously improve the dimensional accuracy of BMG products and life span of casting facilities when manufacturing through various conventional casting methods, which should be important to fabricate macro to nano-sized industrial parts through BMGs.

Improved glass forming ability and soft magnetic properties by minor Mo alloying in Fe–P–C–B–Si bulk metallic glasses

The glass forming ability (GFA), mechanical, corrosion resistance and soft magnetic properties of Fe76-xP8C6B6Si4Mox (x = 0, 0.5, 1, 1.5 and 2 at. %) bulk metallic glasses (BMGs) were investigated. It was shown that the GFA of this BMGs system is greatly enhanced from the critical diameter of 1 mm for base alloy to 5 mm for the alloy with the addition of 2 at. % Mo. The highest fracture strength of the BMG with 1.5 at. % Mo alloying reached 3.1 GPa. The corrosion resistance featured by corrosion voltage and current density and the passivating ability of these BMGs was obviously improved as minor Mo was added. The Mo-alloyed alloys exhibited excellent magnetic properties, e.g., Fe75.5P8C6B6Si4Mo0.5 BMG has an ultra-low coercivity as low as 1.45 A/m combined with high saturation magnetization of 1.41 T and effective permeability of about 5700 at 1 kHz. The mechanism for the excellent GFA and soft magnetic properties led by minor Mo alloying was discussed in detail. It is believed that these BMGs have great potential for future industrial applications, such as the fabrication of high-frequency soft magnetic composite materials.

In Situ Scattering Studies of Crystallization Kinetics in a Phase-Separated Zr–Cu–Fe–Al Bulk Metallic Glass

Thermal stability and the crystallization kinetics of a phase-separated Zr–Cu–Fe–Al bulk metallic glass were investigated using in situ high-energy synchrotron X-ray and neutron diffraction, as well as small-angle synchrotron X-ray scattering. It was revealed that this glass with excellent glass-forming ability possesses a two-step crystallization behavior. The crystalline products and their evolution sequence are more complicated than a homogeneous Zr–Cu–Al glass with average glass-forming ability. The experimental results indicate that a finely distributed nanometer-sized cubic Zr2Cu phase forms first and then transforms to a tetragonal Zr2Cu phase, while the matrix transforms to an orthorhombic Zr3Fe phase. The strength of the Zr–Cu–Fe–Al composite containing cubic Zr2Cu phase and glass matrix increases, and the plasticity also improves compared to the as-cast Zr–Cu–Fe–Al bulk metallic glass. Our results suggest that the formation of multiple and complex crystalline products would be the characteristics of the Zr–Cu–Fe–Al glass with better glass-forming ability. Our study may shed light on the synthesis of bulk-sized glass–nanocrystals composites of high strength and good plasticity.

Glass formation, magnetic properties, and electrical resistivity of the multi-component FeNbBCuNiCo amorphous alloys

Abstract The effects of additions of Co and Ni to the FeNbBCu alloys on the glass forming ability (GFA), soft magnetic properties and electrical resistivity of Fe-based amorphous alloys were studied by means of X-ray diffraction, differential scanning calorimetry, vibrating sample magnetometry and four-probe testing. The Fe80–x–y Nb5B14Cu1Co x Ni y alloys exhibit high thermal stability and excellent GFA with T x1 ≥ 735 K and T x1/T m ≥ 0.539. They also show excellent soft magnetic properties with high saturation magnetization of 93– 101 emu g–1 and low coercivity of 0.04 –2.37 Oe. The electrical resistivity of these alloys ranges from 121 μΩ cm to 163 μΩ cm. The newly developed FeNbBCu-CoNi glassy alloys not only possess good GFA and high thermal stability, but also have excellent magnetic properties, high electrical resistivity and low cost. With such promising properties, these alloys have potential for industrial applications.

Detailed structural analysis of amorphous Pd40Cu40P20: Comparison with the metallic glass Pd40Ni40P20 from the viewpoint of glass forming ability

To clarify the relationship between the glass-forming ability (GFA) and local atomic structure of Pd-based metallic glasses, the structures of an amorphous Pd40Cu40P20 (PCP) were investigated using the same methods as for Pd40Ni40P20 (PNP) metallic glass, i.e., by a combination of anomalous X-ray scattering, X-ray and neutron diffraction, and reverse Monte Carlo modeling. From the comparison between the results of PNP with an excellent GFA and the PCP with a worse GFA, important features characteristic to the GFA are found in the hyper-ordered structures. Firstly, the compositional inhomogeneity of Cu in PCP is larger than Ni in PNP. Secondly, a Voronoi tessellation reveals that icosahedral arrangements are found with considerable probability around the Ni atoms in PNP, while a less existence around the Cu atoms in PCP. Thirdly, a persistent homology (PH) analysis shows smaller intermediate-size Cu PH rings in PCP than Ni PH rings in PNP.

Improving glass forming ability of off-eutectic metallic glass formers by manipulating primary crystallization reactions

Glass forming ability (GFA) is critically important for large-scale applications of bulk metallic glasses with maximized functionalities at low costs in materials and processing. Traditionally, excellent glass formers usually have compositions in eutectic regions where liquid phases have high stability and low liquid temperatures while GFA of off-eutectic alloys is largely limited by primary crystallization. In this study we reported that the GFA of Ni-based off-eutectic alloys can be dramatically improved by manipulating the primary crystallization reaction through minor alloying. As a result, a novel Ni60Pd20P14Si2B4 metallic glass with excellent GFA is developed by substituting P in Ni60Pd20P20 using 2 at.% Si and 4 at.% B. The minor alloying leads to the transition of the primary crystallization from a tetragonal (Ni, Pd)3P phase to a chemically modulated complex monoclinic phase. The enhanced GFA results in the largest achievable processing diameter (25 mm) of Ni-based bulk metallic glasses, which is more than four times larger than that of Ni60Pd20P20. The complex crystal structure of the primary crystalline phase with chemical modulation and a large unit cell leads to slow crystal growth, and hence the improved stability of supercooled liquid for better GFA.

Improving Glass Forming Ability of Off-Eutectic Metallic Glass Formers by Manipulating Primary Crystallization Reactions

Glass forming ability (GFA) is critically important for large-scale applications of bulk metallic glasses with maximized functionalities at low costs in materials and processing. Traditionally, excellent glass formers usually have compositions in eutectic regions where liquid phases have high stability and low liquid temperatures while GFA of off-eutectic alloys is largely limited by primary crystallization. In this study we reported that the GFA of Ni-based off-eutectic alloys can be dramatically improved by manipulating the primary crystallization reaction through minor alloying. As a result, a novel Ni60Pd20P14Si2B4 metallic glass with excellent GFA is developed by substituting P in Ni60Pd20P14Si2B4 using 2 at.% Si and 4 at.% B. The minor alloying leads to the transition of the primary crystallization from a tetragonal (Ni, Pd)3P phase to a chemically modulated complex monoclinic phase. The enhanced GFA results in the largest achievable processing diameter (25 mm) of Ni-based bulk metallic glasses, which is more than four times larger than that of Ni60Pd20P14Si2B4 . The complex crystal structure of the primary crystalline phase with chemical modulation and a large unit cell leads to slow crystallization kinetics from high barrier energy for crystal nucleation and growth, and hence the improved glass forming ability.

Metallic Glacial Glass Formation by a First-Order Liquid-Liquid Transition.

The glacial phase, with an apparently glassy structure, can be formed by a first-order transition in some molecular-glass-forming supercooled liquids. Here we report the formation of metallic glacial glass (MGG) from the precursor of a rare-earth-element-based metallic glass via the first-order phase transition in its supercooled liquid. The excellent glass-forming ability of the precursor ensures the MGG to be successfully fabricated into bulk samples (with a minimal critical diameter exceeding 3 mm). Distinct enthalpy, structure, and property changes are detected between MGG and metallic glass, and the reversed "melting-like" transition from the glacial phase to the supercooled liquid is observed in fast differential scanning calorimetry. The kinetics of MGG formation is reflected by a continuous heating transformation diagram, with the phase transition pathways measured at different heating rates taken into account. The finding supports the scenario of liquid-liquid transition in metallic-glass-forming liquids.

Physical, thermal and absorption traits of lithium strontium zinc borate glasses: Sensitiveness on Dy3+ doping

The development and ultimate acceptance of the glassy materials for the industrial applications depend directly on their ambient stability determined by the host compositions. Accordingly, some new types of dysprosium ions (Dy3+)-doped lithium strontium zinc borate (LSZB) glasses were prepared using the conventional melt quenching. The prepared glasses were characterized via different measurements to determine the sensitiveness of the varying Dy3+ doping levels on their physical, thermal and optical absorbance characteristics. The XRD analysis of the as-quenched samples confirmed their amorphous nature. The UV–Vis–NIR spectra of the glasses displayed nine absorption bands where the hypersensitive transition (6F11/2+6H9/2) was positioned around 1270 nm. In addition, the ASF, DASF and Tauc methods were used to evaluate the optical band gap energies of the studied glasses. The DTA results of the glasses revealed excellent thermal stability (Hurby parameter of 2.44 and stability against crystallization of 114) and glass-forming ability in the range of 1.34–2.44. The physical, structural, thermal and optical absorption properties of the studied glasses were observed to be highly sensitive to the Dy+3 doping levels. It was shown that by controlling the Dy3+ contents in the proposed compositions their overall traits can be tailored. The proposed glasses with excellent thermal stability, high transparency and very low signal loss indicated their potential for the optical fibres drawing. It is established that the present disclosure may contribute towards the development of the glass-based low loss optical fibres needed for various applied purposes.

Fracture response of [formula omitted] bulk metallic glass subjected to quasi-static compression loading

Lanthanum based bulk metallic glass (BMG) is one of the BMG which have the excellent glass-forming ability (GFA). In this empirical study, as-received La61.4Al15.9Ni11.35Cu11.35 bulk metallic glasses were subjected to a quasi-static compression test. The results show the maximum modulus Young’s of 191 GPa, the compressive force of 590 MPa and the compressive displacement at maximum force of 0.35 mm. The La-based BMG were comparable to the 304 stainless steels in term of the mechanical properties. The La-based BMG fracture response from the quasi-static compression test was documented. The fracture response under compressive loading is vital to understand the La-based BMG for the promising used in lightweight alloy applications.