Development Of Bulk Metallic Glasses Research Articles

Enhanced Mechanical, Thermal and Electrical Properties of High‐Entropy HfMoNbTaTiVWZr Thin Film Metallic Glass and its Nitrides

The inception of high‐entropy alloy promises to push the boundaries for new alloy design with unprecedented properties. This work reports entropy stabilisation of an octonary refractory, HfMoNbTaTiVWZr, high‐entropy thin film metallic glass, and derived nitride films. The thin film metallic glass exhibited exceptional ductility of ≈60% strain without fracture and compression strength of 3 GPa in micro‐compression, due to the presence of high density and strength of bonds. The thin film metallic glass shows thermal stability up to 750 °C and resistance to Ar‐ion irradiation. Nitriding during film deposition of HfMoNbTaTiVWZr thin film of strong nitride forming refractory elements results in deposition of nanocrystalline nitride films with compressive strength, hardness, and thermal stability of up to 10 GPa, 18.7 GPa, and 950 °C, respectively. The high amount of lattice distortion in the nitride films leads to its insulating behaviour with electrical conductivity as low as 200 S cm−1 in the as‐deposited film. The design and exceptional properties of the thin film metallic glass and derived nitride films may open up new avenues of development of bulk metallic glasses and the application of refractory‐based high entropy thin films in structural and functional applications.

Recent development of chemically complex metallic glasses: from accelerated compositional design, additive manufacturing to novel applications

Abstract Metallic glasses (MGs) or amorphous alloys are an important engineering material that has a history of research of about 80–90 years. While different fast cooling methods were developed for multi-component MGs between 1960s and 1980s, 1990s witnessed a surge of research interest in the development of bulk metallic glasses (BGMs). Since then, one central theme of research in the metallic-glass community has been compositional design that aims to search for MGs with a better glass forming ability, a larger size and/or more interesting properties, which can hence meet the demands from more important applications. In this review article, we focus on the recent development of chemically complex MGs, such as high entropy MGs, with new tools that were not available or mature yet until recently, such as the state-of-the-art additive manufacturing technologies, high throughput materials design techniques and the methods for big data analyses (e.g. machine learning and artificial intelligence). We also discuss the recent use of MGs in a variety of novel and important applications, from personal healthcare, electric energy transfer to nuclear energy that plays a pivotal role in the battle against global warming.

Investigation of Mechanical and Magnetic Properties of Co-Based Amorphous Powders Obtained by Atomization.

Properties of Co-based alloys with high Glass Forming Ability (GFA) in the form of powder are still not widely known. However, powders of high GFA alloys are often used for the development of bulk metallic glasses by additive manufacturing. In this work Co47.6B21.9Fe20.4Si5.1Nb5% at. and Co42B26.5Fe20Ta5.5Si5Cu1% at. were developed by gas-atomization. Obtained powders in size 50–80 µm were annealed at Tg and Tx of each alloy. Then SEM observation, EDS analyses, differential thermal analysis, X-ray diffraction, nanoindentation, Mössbauer, and magnetic properties research was carried out for as-atomized and annealed states. The gas atomization method proved to be an efficient method for manufacturing Co-based metallic glasses. The obtained powder particles were spherical and chemically homogeneous. Annealing resulted in an increase of mechanical properties such as hardness and the elastic module of Co47.6B21.9Fe20.4Si5.1Nb5% at and Co42B26.5Fe20Ta5.5Si5Cu1%, which was caused by crystallization. The magnetic study shows that Co47.6B21.9Fe20.4Si5.1Nb5 and Co42B26.5Fe20Ta5.5Si5Cu1 are soft magnetic and semi-hard magnetic materials, respectively.

RETRACTED: Development of Bulk Metallic Glasses and their Composites by Additive Manufacturing - Evolution, Challenges and a Proposed Novel Solution

RETRACTED ARTICLE: Bulk metallic glasses (BMGs) and their composites (BMGMCs) have emerged as competitive materials for structural engineering applications exhibiting superior tensile strength, hardness along with very large elastic strain limit. However, they suffer from lack of ductility and subsequent low toughness due to the inherent brittleness of the glassy structure which makes them amenable to failure without appreciable yielding. Various mechanisms and methods have been proposed to counter this effect out of which, recently Additive Manufacturing has gained widespread attention. It is proposed that additive manufacturing can overcome these difficulties in single step due to inherent existence of very high cooling rate in the process which is essential for glass formation. This, when coupled with careful selection of alloy chemistry is proposed to be the best solution to fabricate near net shape parts in a single step with excellent properties. In this report, an effort has been made to describe one possible route to achieve this. Solidification processing employing carefully selected inoculants based on edge to edge matching technique along with the carefuly controlled inoculation procedure is proposed to reflect upon enhanced mechanical properties. It is hypothesized that number density, size and distribution of ductile crystalline phase would best be able to improve microstructure and hence properties. This is meant to be controlled by manipulating type, size and the amount of inoculants. The proposed methodology is claimed to bear maximum potential.

Design of Fe-based bulk metallic glasses for maximum amorphous diameter (Dmax) using machine learning models

The development of bulk metallic glasses (BMGs) is a topic of current interest due to the unique set of properties that distinguish them from their crystalline counterpart and make them attractive in industrial applications as both structural and functional materials. Currently, a great effort is being made to model and quantify the glass forming ability of the amorphous in an alloy, as well as in tuning their properties in view of the final application of the material. In this work we have used two machine learning techniques, multiple linear regression and tree boosting, to predict the maximum amorphous diameter of Fe-based BMGs, exclusively from the alloy’s chemical composition. The modeĺs predictive power is characterised by a predicted-R2 of 0.71 (predicted-R = 0.84) and a training-R2 of 0.90 (training-R = 0.95) over a set of 480 alloys present in the dataset. Learning curves are employed as part of a comparative prediction analysis of the two techniques and to help decide the modelling aspects on which effort should be invested in the future. Selected examples using pseudo-ternary diagrams for the design of new Fe-based BMGs are presented, where the potential of the model becomes clear.

Retracted: Development of Bulk Metallic Glasses and their Composites by Additive Manufacturing – Evolution, Challenges and a Proposed Novel Solution

Bulk metallic glasses (BMGs) and their composites (BMGMCs) have emerged as competitive materials for structural engineering applications exhibiting superior tensile strength, hardness along with very large elastic strain limit. However, they suffer from lack of ductility and subsequent low toughness due to the inherent brittleness of the glassy structure which makes them amenable to failure without appreciable yielding. Various mechanisms and methods have been proposed to counter this effect out of which, recently Additive Manufacturing has gained widespread attention. It is proposed that additive manufacturing can overcome these difficulties in single step due to inherent existence of very high cooling rate in the process which is essential for glass formation. This, when coupled with careful selection of alloy chemistry is proposed to be the best solution to fabricate near net shape parts in a single step with excellent properties. In this report, an effort has been made to describe one possible route to achieve this. Solidification processing employing carefully selected inoculants based on edge to edge matching technique along with the carefuly controlled inoculation procedure is proposed to reflect upon enhanced mechanical properties. It is hypothesized that number density, size and distribution of ductile crystalline phase would best be able to improve microstructure and hence properties. This is meant to be controlled by manipulating type, size and the amount of inoculants. The proposed methodology is claimed to bear maximum potential.

Glass formation and soft magnetic properties of novel Fe-rich Fe-B-Ti-Zr bulk metallic glasses

Composition design is an important issue concerning the development of bulk metallic glasses (BMGs), especially applicable Fe-based bulk metallic glasses (BMGs). In this work, new quaternary Fe77B18TixZr5-x (x = 1–4) BMGs were developed by promoting metastable transformation in solidification process. Their glass formation, thermal and soft magnetic properties have been investigated. Thermal analysis proves that the combined additions of Ti and Zr in the alloys have significant advantage in improving the glass forming ability (GFA). However, the alloy with best GFA does not show the optimal thermal performance, and such inconformity in MGs was usually neglected previously. We further explain the origin of the improvement in GFA and the inconformity between GFA and thermal properties by investigating the phase evolution of the crystalline alloys. Proper combined additions of Ti and Zr can promote the precipitation of metastable Fe23B6 phase, which is advantageous to GFA as the diverse crystallization pathways reflect different crystallization resistances in solidification. Owing to the high Fe content, the amorphous ribbons exhibit high saturation induction of over 1.3 T.

Micro-patterning by thermoplastic forming of Ni-free Ti-based bulk metallic glasses

The development of bulk metallic glasses for biomedical applications has become the focus of intense research interest. In this work, we report on the unique thermoplastic behavior of two Ni-free Ti-based bulk metallic glasses by utilizing the dramatic softening of the amorphous structure in the super cooled liquid region. Ti40Zr10Cu34Pd14Ga2 and Ti40Zr10Cu34Pd14Sn2 bulk glassy alloys were produced by copper mold casting. Ga and Sn micro-alloying (2at%) improve the glass-forming ability and mechanical properties of Ti40Zr10Cu36Pd14 alloy effectively. The cast rods were thermo-mechanically characterized to determine the most suitable processing temperature and time, and the load that has to be applied for thermoplastic net-shaping of the BMGs into anisotropically etched cavities of silicon chips. Periodic features with high surface smoothness and uniform height (24μm high circular bumps with sub-μm roughness) were created on the surface of the BMGs. The surface patterning with controllable roughness of Ti-based BMGs can be useful in biomedical studies by mediating material - cell interactions.

Hydrogen microalloying as a viable strategy for enhancing the glass-forming ability of Zr-based bulk metallic glasses

The development of bulk metallic glasses (BMGs) with both high critical casting thickness and ductility is a great challenge. In this study we show that the glass-forming ability (GFA) of ductile Zr-rich Zr–Cu–Al BMGs can be increased by processing the alloys under hydrogen-containing atmosphere. After considering various reasons for this GFA enhancement, we attribute it to hydrogen microalloying, which generates a higher packing density. We also discuss the role of applied hydrogen pressure and present implications for future alloy design.

Combinatorial development of bulk metallic glasses

The identification of multicomponent alloys out of a vast compositional space is a daunting task, especially for bulk metallic glasses composed of three or more elements. Despite an increasing theoretical understanding of glass formation, bulk metallic glasses are predominantly developed through a sequential and time-consuming trial-and-error approach. Even for binary systems, accurate quantum mechanical approaches are still many orders of magnitude away from being able to simulate the relatively slow kinetics of glass formation. Here, we present a high-throughput strategy where ∼3,000 alloy compositions are fabricated simultaneously and characterized for thermoplastic formability through parallel blow forming. Using this approach, we identified the composition with the highest thermoplastic formability in the glass-forming system Mg-Cu-Y. The method provides a versatile toolbox for unveiling complex correlations of material properties and glass formation, and should facilitate a drastic increase in the discovery rate of metallic glasses.

Structural origin of the pinpoint-composition effect on the glass-forming ability in the NiNb alloy system

Abstract

Evaluation of the elastic properties of bulk metallic glasses

The development of bulk metallic glasses as a prominent class of functional and structural materials has attracted considerable interest in the last years. One of the fundamental physical quantities necessary to describe the mechanical properties of the materials is the bulk modulus. In the present article, a simple method to estimate the bulk modulus and its pressure derivative is proposed. It is shown that these quantities can be estimated from the values of the constituent elements and their compositions. Comparison with measured data shows good agreement. The physical background of the method is discussed based on the jellium model of metals.

Development of bulk metallic glasses based on the Dy-Al binary eutectic composition

A series of dysprosium-based ternary, quadruple, and quintuple bulk metallic glasses (BMGs) based on Dy-Al binary eutectic composition were obtained with the partial substitution of Co, Gd, and Ni elements, for dysprosium. The results showed that the Dy 31Gd 25Co 20Al 24 alloy, which had the best glass forming ability (GFA), could be cast into an amorphous rod with a diameter of 5 mm. The GFA of alloys was evaluated on the basis of the supercooled liquid region width, γ parameter, the formation enthalpy, and the equivalent electronegativity difference of amorphous alloys. It was found that the eutectic composition was closely correlated with the GFA of the Dy-based BMGs.

Effect of addition of Be on glass-forming ability, plasticity and structural change in Cu–Zr bulk metallic glasses

The present study reports the effect of the addition of Be in Cu–Zr bulk metallic glass (BMG) on glass-forming ability (GFA), plasticity and structural change. Although Be has a negative enthalpy of mixing with all the constituent elements of these glasses, Cu 47.5Zr 40Be 12.5 alloy exhibits apparent double glass transitions ( T g) and enhanced plasticity as well as improved GFA. Intensive structural analysis using extended X-ray absorption fine structure suggests that a large difference in the enthalpy of mixing between atom pairs in multi-component BMGs can cause atomic scale structural inhomogeneity and/or locally favored structures in the amorphous matrix, resulting in enhanced compressive strains, although the enthalpies of mixing for atom pairs are all negative. This concept may shed light on the development of BMGs with large plasticity as well as high GFA.

Identifying bulk metallic glass-formers from multi-component eutectics

Multi-component eutectics are potentially bulk metallic glass (BMG)-formers, making their compositions the best starting points in the development of BMGs. Here we formulate a thermodynamic strategy to pin down BMG-formers from invariant eutectic compositions calculated using a Calphad approach. Taking Zr–Ti–Cu–Ni as a model system, we demonstrate that 4 out of 14 thermodynamically predicted eutectics are BMG-formers, and, more strikingly, 2 of them are associated with the experimentally observed Zr–Cu-rich and Ti–Cu-rich BMG-forming regions. A variety of new amorphous alloys are also expected by tailoring the compositions of the other 2 BMG-forming eutectics.

Mechanical properties of bulk metallic glasses and composites

The development of bulk metallic glasses and composites for improving the mechanical properties has occurred with the discovery of many ductile metallic glasses and glass matrix composites with second phase dispersions with different length scales. This article reviews the processing, microstructure development, and resulting mechanical properties of Zr-, Ti-, Cu-, Mg-, Fe-, and Ni-based glassy alloys and also considers the superiority of composite materials containing different phases for enhancing the strength, ductility, and toughness, even leading to a “work-hardening-like” behavior. The morphology, shape, and length scale of the second phase dispersions are crucial for the delocalization of shear bands. The article concludes with some comments regarding future directions of the investigations of spatially inhomogeneous metallic glasses.

Classification of Bulk Metallic Glasses by Atomic Size Difference, Heat of Mixing and Period of Constituent Elements and Its Application to Characterization of the Main Alloying Element

Bulk metallic glasses (BMGs) have been classified according to the atomic size difference, heat of mixing (ΔHmix) and period of the constituent elements in the periodic table. The BMGs discovered to date are classified into seven groups on the basis of a previous result by Inoue. The seven groups are as follows: (G-I) ETM/Ln-LTM/BM-Al/Ga, (G-II) ETM/Ln-LTM/BM-Metalloid, (G-III) Al/Ga-LTM/BM-Metalloid, (G-IV) IIA-ETM/Ln-LTM/BM, (G-V) LTM/BM-Metalloid, (G-VI) ETM/Ln-LTM/BM and (G-VII) IIA-LTM/BM, where ETM, Ln, LTM, BM and IIA refer to early transition, lanthanide, late transition, group IIIB–IVB and group IIA-group metals, respectively. The main alloying element of ternary G-I, G-V and G-VII, ternary G-II and G-IV, and ternary G-VI BMGs is the largest, intermediate and smallest atomic radius compared to the other alloying elements, respectively. The main alloying element of ternary BMGs belonging to G-I, G-V, G-VI and G-VII is an element in the atomic pair with the largest and negative value of ΔHmix (ΔHL.N.mix), while the main element of ternary BMGs belonging to G-II and G-IV is independent of the atomic pair with ΔHL.N.mix. The characteristics of the main element derived for the ternary BMGs are directly applicable to multicomponent BMGs belonging to G-I, G-II, G-IV (Mg-based BMGs), G-V and G-VII. The main element can be the larger-sized element in the atomic pair with ΔHL.N.mix or in the same group as the other elements for multicomponent BMGs belonging to G-III, G-IV (Be-containing Zr-based BMG) and G-VI. The main element of BMGs belonging to G-VI tends to change from the element with the smallest atomic radius in a ternary system to an element with a relatively large atomic size in a multicomponent system. The change is due to an increase in glass-forming ability through multicomponent alloying of BMGs belonging to G-VI. The results of the classification of BMGs obtained in the present study are important for further development of BMGs, with the results providing a road map for the development of new BMG compositions.

Bulk metallic glass matrix composites

Composites with a bulk metallic glass matrix were synthesized and characterized. This was made possible by the recent development of bulk metallic glasses that exhibit high resistance to crystallization in the undercooled liquid state. In this letter, experimental methods for processing metallic glass composites are introduced. Three different bulk metallic glass forming alloys were used as the matrix materials. Both ceramics and metals were introduced as reinforcement into the metallic glass. The metallic glass matrix remained amorphous after adding up to a 30 vol% fraction of particles or short wires. X-ray diffraction patterns of the composites show only peaks from the second phase particles superimposed on the broad diffuse maxima from the amorphous phase. Optical micrographs reveal uniformly distributed particles in the matrix. The glass transition of the amorphous matrix and the crystallization behavior of the composites were studied by calorimetric methods.

Thermodynamic and mechanical properties of Zr-based bulk metallic glasses

Glasses are generally produced from the highly undercooled liquid state by rapid quenching methods or quasistatically at slow cooling by the effective control of potent heterogeneous nucleation sites. For metallic systems the latter method recently has led to the development of bulk metallic glasses, so-called supermetals, with a complex multicomponent chemistry and advanced engineering properties. As long as crystallization can be prevented, the relevant thermodynamic properties of the metastable glassy and undercooled liquid phases can be measured below and above the glass transition temperature respectively. The data suggest that the glass transition corresponds to kinetic freezing triggered by an underlying entropic instability. Further measurements of the mechanical and wear properties of these new metastable materials point to unique engineering properties for technological applications.

Metastability and Properties of Metallic Bulk Glass Forming Alloys

ABSTRACTGlasses are generally produced from the highly undercooled liquid state by rapid quenching methods or quasi-statically at slow cooling by the effective control of potent heterogeneous nucleation sites. For metallic systems the latter method recently has led to the development of bulk metallic glass with a complex multicomponent chemistry and advanced engineering properties. With these alloys crystallization can be avoided over a broad temperature / time window. As such, the relevant thermodynamic properties of the metastable glassy and undercooled liquid states can be directly measured below and above the glass transition temperature, respectively. The obtained data give new insight into the nature of the glass transition suggesting that it is not a phase transition in the classical sense but kinetic freezing triggered by an underlying entropie instability to avoid crystallization. Further measurements of the mechanical and wear properties point to the unique engineering properties of these highly disordered materials for technological applications.