Special Issue "Metallic Glasses"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (30 April 2015)

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Guest Editor
Prof. Dr. K.C. Chan

Advanced Manufacturing Technology Research Centre, Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
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Interests: bulk metallic glasses, superplasticity, processing and properties of advanced materials
Guest Editor
Prof. Dr. Jordi Sort Viñas

Institució Catalana de Recerca i Estudis Avançats (ICREA) and Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
Website | E-Mail
Interests: nanocrystalline alloys, metallic glasses, metallic films and patterned structures, nanomechanical properties, magnetic behaviour, phase transformations, modeling

Special Issue Information

Dear Colleagues,

Metallic glasses, a family of metallic materials with metastable glassy states, are obtained by rapid cooling of liquid alloys. Because of their amorphous atomic structures, metallic glasses exhibit unique mechanical, physical, and chemical properties, which are superior to conventional metals’ and alloys’, within a wide range of potential applications.

With the combination of high strength, elasticity, and fracture resistance, bulk metallic glasses (BMGs) have attracted tremendous research interest over the past few decades. However, low tensile ductility is still one of the key issues of BMGs in structural applications. Due to its high accuracy in replicating complicated mold shapes, the die casting technique has been successfully applied to produce BMG products. On the other hand, metallic glasses can also be formed into complex shapes, like plastics, in the supercooled liquid region, due to their high thermal-plastic forming abilities.

In addition to their unique mechanical properties, metallic glasses have also demonstrated interesting physical and chemical properties. For example, some metallic glasses have been found to have good magnetocaloric effects and display catalytic behavior, with potential for magnetic refrigeration or catalytic applications. In recent years, metallic glass thin films and coatings have also drawn much attention due to their potential engineering and biomedical applications.

Up to now, despite the encouraging achievements, the wide application of metallic glasses is still somewhat hindered by the mysterious physical origins of the unique properties, and by the difficulties in exploiting the alloys with benchmark performances. The wide range of studies will continue to further uncover the underlying physical meanings, and to expand the application potential of metallic glasses. Papers on recent advances, and review articles, particularly in regard to fundamental properties and the structural and functional applications of metallic glasses, are invited for inclusion in this Special Issue on "Metallic Glasses".

Prof. K.C. Chan
Prof. Dr Jordi Sort Viñas
Guest Editors

Manuscript Submission Information

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Keywords

  • bulk metallic glasses
  • metallic glass thin films or coatings
  • mechanical and physical properties
  • thermal-plastic forming ability
  • structural and functional applications

Published Papers (12 papers)

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Editorial

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Open AccessEditorial Metallic Glasses
Metals 2015, 5(4), 2397-2400; doi:10.3390/met5042397
Received: 15 December 2015 / Accepted: 15 December 2015 / Published: 16 December 2015
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Abstract
Metallic glasses are a fascinating class of metallic materials that do not display long-range atomic order. [...] Full article
(This article belongs to the Special Issue Metallic Glasses) Printed Edition available

Research

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Open AccessArticle Deformation-Induced Martensitic Transformation in Cu-Zr-Zn Bulk Metallic Glass Composites
Metals 2015, 5(4), 2134-2147; doi:10.3390/met5042134
Received: 23 October 2015 / Revised: 7 November 2015 / Accepted: 11 November 2015 / Published: 17 November 2015
Cited by 3 | PDF Full-text (691 KB) | HTML Full-text | XML Full-text
Abstract
The microstructures and mechanical properties of (Cu0.5Zr0.5)100−xZnx (x = 0, 1.5, 2.5, 4.5, 7, 10, and 14 at. %) bulk metallic glass (BMG) composites were studied. CuZr martensitic crystals together with minor B2 CuZr
[...] Read more.
The microstructures and mechanical properties of (Cu0.5Zr0.5)100−xZnx (x = 0, 1.5, 2.5, 4.5, 7, 10, and 14 at. %) bulk metallic glass (BMG) composites were studied. CuZr martensitic crystals together with minor B2 CuZr and amorphous phases dominate the microstructures of the as-quenched samples with low Zn additions (x = 0, 1.5, and 2.5 at. %), while B2 CuZr and amorphous phases being accompanied with minor martensitic crystals form at a higher Zn content (x = 4.5, 7, 10, and 14 at. %). The fabricated Cu-Zr-Zn BMG composites exhibit macroscopically appreciable compressive plastic strain and obvious work-hardening due to the formation of multiple shear bands and the deformation-induced martensitic transformation (MT) within B2 crystals. The present BMG composites could be a good candidate as high-performance structural materials. Full article
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Figures

Open AccessArticle Effect of Yttrium Addition on Glass-Forming Ability and Magnetic Properties of Fe–Co–B–Si–Nb Bulk Metallic Glass
Metals 2015, 5(3), 1127-1135; doi:10.3390/met5031127
Received: 28 April 2015 / Revised: 20 June 2015 / Accepted: 23 June 2015 / Published: 29 June 2015
Cited by 3 | PDF Full-text (662 KB) | HTML Full-text | XML Full-text
Abstract
The glass-forming ability (GFA) and the magnetic properties of the [(Fe0.5Co0.5)0.75B0.20Si0.05]96Nb4−xYx bulk metallic glasses (BMGs) have been studied. The partial replacement of Nb by Y
[...] Read more.
The glass-forming ability (GFA) and the magnetic properties of the [(Fe0.5Co0.5)0.75B0.20Si0.05]96Nb4−xYx bulk metallic glasses (BMGs) have been studied. The partial replacement of Nb by Y improves the thermal stability of the glass against crystallization. The saturation mass magnetization (σs) exhibits a maximum around 2 at. % Y, and the value of σs of the alloy with 2 at. % Y is 6.5% larger than that of the Y-free alloy. The coercivity shows a tendency to decrease with increasing Y content. These results indicate that the partial replacement of Nb by Y in the Fe–Co–B–Si–Nb BMGs is useful to simultaneous achievement of high GFA, high σs, and good soft magnetic properties. Full article
(This article belongs to the Special Issue Metallic Glasses) Printed Edition available
Open AccessArticle On the Stability of the Melt Jet Stream during Casting of Metallic Glass Wires
Metals 2015, 5(2), 1029-1044; doi:10.3390/met5021029
Received: 19 May 2015 / Revised: 31 May 2015 / Accepted: 2 June 2015 / Published: 8 June 2015
Cited by 2 | PDF Full-text (514 KB) | HTML Full-text | XML Full-text
Abstract
The factors that affect the stability of the melt stream during the casting of wire directly from the melt have been investigated. It is shown that the criticality of process parameters centres mostly on the forces imposed on the melt stream at confluence
[...] Read more.
The factors that affect the stability of the melt stream during the casting of wire directly from the melt have been investigated. It is shown that the criticality of process parameters centres mostly on the forces imposed on the melt stream at confluence with the cooling water. The analysis of these forces indicated that the shear component of the disturbance is dependent on the ratio of the velocity of the melt stream (vm) to that of the cooling water (vw) in accord with results obtained from previous experiments. The role of oxide-forming elements in widening the process parameters range is attributed to the increased stability of the melt stream due to the additional shear force resistance offered by the solid oxide layer. The roles of Cr and Si oxides in stabilising the melt stream are confirmed by X-ray photoelectron spectroscopy (XPS) of wire indicating the presence of these oxides on fresh as-cast wires. Melt superheat and nozzle clearance distance are not strictly stream stability factors, but rather their role in glass formation prescribes optimal limits for fully amorphous wire. Full article
(This article belongs to the Special Issue Metallic Glasses) Printed Edition available
Open AccessArticle Mechanical and Structural Investigation of Porous Bulk Metallic Glasses
Metals 2015, 5(2), 920-933; doi:10.3390/met5020920
Received: 28 April 2015 / Revised: 20 May 2015 / Accepted: 25 May 2015 / Published: 2 June 2015
Cited by 6 | PDF Full-text (2959 KB) | HTML Full-text | XML Full-text
Abstract
The intrinsic properties of advanced alloy systems can be altered by changing their microstructural features. Here, we present a highly efficient method to produce and characterize structures with systematically-designed pores embedded inside. The fabrication stage involves a combination of photolithography and deep reactive
[...] Read more.
The intrinsic properties of advanced alloy systems can be altered by changing their microstructural features. Here, we present a highly efficient method to produce and characterize structures with systematically-designed pores embedded inside. The fabrication stage involves a combination of photolithography and deep reactive ion etching of a Si template replicated using the concept of thermoplastic forming. Pt- and Zr-based bulk metallic glasses (BMGs) were evaluated through uniaxial tensile test, followed by scanning electron microscope (SEM) fractographic and shear band analysis. Compositional investigation of the fracture surface performed via energy dispersive X-ray spectroscopy (EDX), as well as Auger spectroscopy (AES) shows a moderate amount of interdiffusion (5 at.% maximum) of the constituent elements between the deformed and undeformed regions. Furthermore, length-scale effects on the mechanical behavior of porous BMGs were explored through molecular dynamics (MD) simulations, where shear band formation is observed for a material width of 18 nm. Full article
(This article belongs to the Special Issue Metallic Glasses) Printed Edition available
Open AccessArticle Effect of Milling Time and the Consolidation Process on the Properties of Al Matrix Composites Reinforced with Fe-Based Glassy Particles
Metals 2015, 5(2), 669-685; doi:10.3390/met5020669
Received: 27 March 2015 / Revised: 19 April 2015 / Accepted: 22 April 2015 / Published: 27 April 2015
Cited by 7 | PDF Full-text (1909 KB) | HTML Full-text | XML Full-text
Abstract
Al matrix composites reinforced with 40 vol% Fe50.1Co35.1Nb7.7B4.3Si2.8 glassy particles have been produced by powder metallurgy, and their microstructure and mechanical properties have been investigated in detail. Different processing routes (hot pressing and hot
[...] Read more.
Al matrix composites reinforced with 40 vol% Fe50.1Co35.1Nb7.7B4.3Si2.8 glassy particles have been produced by powder metallurgy, and their microstructure and mechanical properties have been investigated in detail. Different processing routes (hot pressing and hot extrusion) are used in order to consolidate the composite powders. The homogeneous distribution of the glassy reinforcement in the Al matrix and the decrease of the particle size are obtained through ball milling. This has a positive effect on the hardness and strength of the composites. Mechanical tests show that the hardness of the hot pressed samples increases from 51–155 HV, and the strength rises from 220–630 MPa by extending the milling time from 1–50 h. The use of hot extrusion after hot pressing reduces both the strength and hardness of the composites: however, it enhances the plastic deformation significantly. Full article
(This article belongs to the Special Issue Metallic Glasses) Printed Edition available
Open AccessArticle A New Ni-Based Metallic Glass with High Thermal Stability and Hardness
Metals 2015, 5(1), 162-171; doi:10.3390/met5010162
Received: 20 October 2014 / Revised: 9 January 2015 / Accepted: 27 January 2015 / Published: 2 February 2015
Cited by 3 | PDF Full-text (780 KB) | HTML Full-text | XML Full-text
Abstract
Glass forming ability (GFA), thermal stability and microhardness of Ni51−xCuxW31.6B17.4 (x = 0, 5) metallic glasses have been investigated. For each alloy, thin sheets of samples having thickness of 20 µm and 100 µm
[...] Read more.
Glass forming ability (GFA), thermal stability and microhardness of Ni51−xCuxW31.6B17.4 (x = 0, 5) metallic glasses have been investigated. For each alloy, thin sheets of samples having thickness of 20 µm and 100 µm were synthesized by piston and anvil method in a vacuum arc furnace. Also, 400 µm thick samples of the alloys were synthesized by suction casting method. The samples were investigated by X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). Crystallization temperature of the base alloy, Ni51W31.6B17.4, is found to be 996 K and 5 at.% copper substitution for nickel increases the crystallization temperature to 1063 K, which is the highest value reported for Ni-based metallic glasses up to the present. In addition, critical casting thickness of alloy Ni51W31.6B17.4 is 100 µm and copper substitution does not have any effect on critical casting thickness of the alloys. Also, microhardness of the alloys are found to be around 1200 Hv, which is one of the highest microhardness values reported for a Ni-based metallic glass until now. Full article
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Review

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Open AccessReview Toughness of Bulk Metallic Glasses
Metals 2015, 5(3), 1279-1305; doi:10.3390/met5031279
Received: 1 June 2015 / Revised: 6 July 2015 / Accepted: 10 July 2015 / Published: 17 July 2015
Cited by 14 | PDF Full-text (1337 KB) | HTML Full-text | XML Full-text
Abstract
Bulk metallic glasses (BMGs) have desirable properties like high strength and low modulus, but their toughness can show much variation, depending on the kind of test as well as alloy chemistry. This article reviews the type of toughness tests commonly performed and the
[...] Read more.
Bulk metallic glasses (BMGs) have desirable properties like high strength and low modulus, but their toughness can show much variation, depending on the kind of test as well as alloy chemistry. This article reviews the type of toughness tests commonly performed and the factors influencing the data obtained. It appears that even the less-tough metallic glasses are tougher than oxide glasses. The current theories describing the links between toughness and material parameters, including elastic constants and alloy chemistry (ordering in the glass), are discussed. Based on the current literature, a few important issues for further work are identified. Full article
(This article belongs to the Special Issue Metallic Glasses) Printed Edition available
Open AccessReview Stress-Corrosion Interactions in Zr-Based Bulk Metallic Glasses
Metals 2015, 5(3), 1262-1278; doi:10.3390/met5031262
Received: 7 May 2015 / Revised: 8 July 2015 / Accepted: 10 July 2015 / Published: 15 July 2015
Cited by 1 | PDF Full-text (910 KB) | HTML Full-text | XML Full-text
Abstract
Stress-corrosion interactions in materials may lead to early unpredictable catastrophic failure of structural parts, which can have dramatic effects. In Zr-based bulk metallic glasses, such interactions are particularly important as these have very high yield strength, limited ductility, and are relatively susceptible to
[...] Read more.
Stress-corrosion interactions in materials may lead to early unpredictable catastrophic failure of structural parts, which can have dramatic effects. In Zr-based bulk metallic glasses, such interactions are particularly important as these have very high yield strength, limited ductility, and are relatively susceptible to localized corrosion in halide-containing aqueous environments. Relevant features of the mechanical and corrosion behavior of Zr-based bulk metallic glasses are described, and an account of knowledge regarding corrosion-deformation interactions gathered from ex situ experimental procedures is provided. Subsequently the literature on key phenomena including hydrogen damage, stress corrosion cracking, and corrosion fatigue is reviewed. Critical factors for such phenomena will be highlighted. The review also presents an outlook for the topic. Full article
(This article belongs to the Special Issue Metallic Glasses) Printed Edition available
Open AccessReview Dynamics and Geometry of Icosahedral Order in Liquid and Glassy Phases of Metallic Glasses
Metals 2015, 5(3), 1163-1187; doi:10.3390/met5031163
Received: 22 May 2015 / Revised: 24 June 2015 / Accepted: 25 June 2015 / Published: 2 July 2015
Cited by 2 | PDF Full-text (6691 KB) | HTML Full-text | XML Full-text
Abstract
The geometrical properties of the icosahedral ordered structure formed in liquid and glassy phases of metallic glasses are investigated by using molecular dynamics simulations. We investigate the Zr-Cu alloy system as well as a simple model for binary alloys, in which we can
[...] Read more.
The geometrical properties of the icosahedral ordered structure formed in liquid and glassy phases of metallic glasses are investigated by using molecular dynamics simulations. We investigate the Zr-Cu alloy system as well as a simple model for binary alloys, in which we can change the atomic size ratio between alloying components. In both cases, we found the same nature of icosahedral order in liquid and glassy phases. The icosahedral clusters are observed in liquid phases as well as in glassy phases. As the temperature approaches to the glass transition point Tg, the density of the clusters rapidly grows and the icosahedral clusters begin to connect to each other and form a medium-range network structure. By investigating the geometry of connection between clusters in the icosahedral network, we found that the dominant connecting pattern is the one sharing seven atoms which forms a pentagonal bicap with five-fold symmetry. From a geometrical point of view, we can understand the mechanism of the formation and growth of the icosahedral order by using the Regge calculus, which is originally employed to formulate a theory of gravity. The Regge calculus tells us that the distortion energy of the pentagonal bicap could be decreased by introducing an atomic size difference between alloying elements and that the icosahedral network would be stabilized by a considerably large atomic size difference. Full article
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Figures

Open AccessReview Mechanical Relaxation of Metallic Glasses: An Overview of Experimental Data and Theoretical Models
Metals 2015, 5(2), 1073-1111; doi:10.3390/met5021073
Received: 20 May 2015 / Revised: 11 June 2015 / Accepted: 12 June 2015 / Published: 19 June 2015
Cited by 13 | PDF Full-text (1945 KB) | HTML Full-text | XML Full-text
Abstract
Relaxation phenomena in glasses are a subject of utmost interest, as they are deeply connected with their structure and dynamics. From a theoretical point of view, mechanical relaxation allows one to get insight into the different atomic-scale processes taking place in the glassy
[...] Read more.
Relaxation phenomena in glasses are a subject of utmost interest, as they are deeply connected with their structure and dynamics. From a theoretical point of view, mechanical relaxation allows one to get insight into the different atomic-scale processes taking place in the glassy state. Focusing on their possible applications, relaxation behavior influences the mechanical properties of metallic glasses. This paper reviews the present knowledge on mechanical relaxation of metallic glasses. The features of primary and secondary relaxations are reviewed. Experimental data in the time and frequency domain is presented, as well as the different models used to describe the measured relaxation spectra. Extended attention is paid to dynamic mechanical analysis, as it is the most important technique allowing one to access the mechanical relaxation behavior. Finally, the relevance of the relaxation behavior in the mechanical properties of metallic glasses is discussed. Full article
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Figures

Open AccessReview Understanding of the Structural Relaxation of Metallic Glasses within the Framework of the Interstitialcy Theory
Metals 2015, 5(2), 504-529; doi:10.3390/met5020504
Received: 31 January 2015 / Revised: 18 March 2015 / Accepted: 19 March 2015 / Published: 25 March 2015
Cited by 20 | PDF Full-text (1044 KB) | HTML Full-text | XML Full-text
Abstract
A review of the new approach to the understanding of the structural relaxation of metallic glasses based on the interstitialcy theory has been presented. The key hypothesis of this theory proposed by Granato consists of the statement that the thermodynamic properties of crystalline,
[...] Read more.
A review of the new approach to the understanding of the structural relaxation of metallic glasses based on the interstitialcy theory has been presented. The key hypothesis of this theory proposed by Granato consists of the statement that the thermodynamic properties of crystalline, liquid and glassy states are closely related to the interstitial defects in the dumbbell (split) configuration, called also interstitialcies. It has been argued that structural relaxation of metallic glasses takes place through a change of the concentration of interstitialcy defects frozen-in from the melt upon glass production. Because of a strong interstitialcy-induced shear softening, the defect concentration can be precisely monitored by measurements of the unrelaxed shear modulus. Depending on the relation between the current interstitialcy concentration c and interstitialcy concentration in the metastable equilibrium, different types of structural relaxation (decreasing or increasing c) can be observed. It has been shown that this approach leads to a correct description of the relaxation kinetics at different testing conditions, heat effects occurring upon annealing, shear softening and a number of other structural relaxation-induced phenomena in metallic glasses. An intrinsic relation of these phenomena with the anharmonicity of the interatomic interaction has been outlined. A generalized form of the interstitialcy approach has been reviewed. Full article
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