The elastic properties, elastic models and elastic perspectives of metallic glasses

Bulk metallic glass (BMG) provides plentiful precise knowledge of fundamental parameters of elastic moduli, which offer a benchmark reference point for understanding and applications of the glassy materials. This paper comprehensively reviews the current state of the art of the study of elastic properties, the establishments of correlations between elastic moduli and properties/features, and the elastic models and elastic perspectives of metallic glasses. The goal is to show the key roles of elastic moduli in study, formation, and understanding of metallic glasses, and to present a comprehensive elastic perspectives on the major fundamental issues from processing to structure to properties in the rapidly moving field.A plentiful of data and results involving in acoustic velocities, elastic constants and their response to aging, relaxation, applied press, pressure and temperature of the metallic glasses have been compiled. The thermodynamic and kinetic parameters, stability, mechanical and physical properties of various available metallic glasses especially BMGs have also been collected. A survey based on the plentiful experimental data reveals that the linear elastic constants have striking systematic correlations with the microstructural features, glass transition temperature, melting temperature, relaxation behavior, boson peak, strength, hardness, plastic yielding of the glass, and even rheological properties of the glass forming liquids. The elastic constants of BMGs also show a correlation with a weighted average of the elastic constants of the constituent elements. We show that the elastic moduli correlations can assist in selecting alloying components with suitable elastic moduli for controlling the elastic properties and glass-forming ability of the metallic glasses, and thus the results would enable the design, control and tuning of the formation and properties of metallic glasses.We demonstrate that the glass transition, the primary and secondary relaxations, plastic deformation and yield can be attributed to the free volume increase induced flow, and the flow can be modeled as the activated hopping between the inherent states in the potential energy landscape. We then propose an extended elastic model to understand flow in metallic glass and glass-forming supercooled liquid, and the model presents a simple and quantitative mathematic expression for flow activation energy of various glasses. The elastic perspectives, which consider all metallic glasses exhibit universal behavior based on a small number of readily measurable parameters of elastic moduli, are presented for understanding the nature and diverse properties of the metallic glasses.     

Bulk metallic glasses: A new class of engineering materials

Bulk glass-forming alloys have emerged over the past fifteen years with attractive properties and technological promise. A number of alloy systems based on lanthanum, magnesium, zirconium, palladium, iron, cobalt and nickel have been discovered. Glass-forming ability depends on various factors like enthalpy of mixing, atomic size and multicomponent alloying. A number of processes is available to synthesise bulk metallic glasses. The crystallisation behaviour and mechanical properties of these alloys pose interesting scientific questions. Upon crystallisation many of these glasses transform to bulk nanocrystals and nanoquasicrystals. A detailed study of the structure and the crystallisation behaviour of glasses has enabled the elucidation of the possible atomic configuration in liquid alloys. Their crystallisation behaviour can be exploited to synthesise novel nanocomposite microstructures and their mechanical properties can be enhanced. A broad overview of the present status of the science and technology of bulk metallic glasses and their potential technological uses is presented.     

Internal friction and elastic modulus of bulk metallic glasses

The mechanical relaxation in binary, ternary, quaternary, and quitary bulk metallic glasses with widely different glass-forming ability, or the critical cooling rate, has been studied. A single-roller melt-spinning apparatus was used for preparing thin specimens. The internal friction Q⁻¹ and the oscillation frequency f of the specimens were measured using an inverted torsion pendulum with the free decay method. The measurements were performed from room temperature, through the glass transition temperature T_g, up to the crystallization temperature T_x. As the temperature is increased, the background Q⁻¹ increases, and peaks can usually be seen near T_g and T_x. The shear modulus, which is proportional to f², is changed near the Q⁻¹ peak. The experimental data are presented and overall features of the results are discussed.     

Influence of thermal treatments on the elastic parameters in iron rich metallic glasses

The change of magnetoelastic properties after thermal treatments has been investigated for two groups of metallic glasses. (Fe₇₉Co₂₁)_75+xSi_15−1.4xB_10+0.4x (x (at.%)=0, 2, 4, 6, 8, 10) has been studied both in the as-prepared state and after thermal annealing in an applied magnetic field, to achieve a particular domain structure, at temperatures well below the crystallization temperatures. Changes in the ΔE effect, magnetomechanical coupling (k) and internal friction coefficient (Q⁻¹) are reported, reaching values of about 60% of the saturation value E_S. Fe₆₄Ni₁₀Nb₃Cu₁Si₁₃B₉ alloys annealed in vacuum for 1 h in the temperature range 350–550 °C showed maximum values of the ΔE effect and k of 61% and 0.85, respectively, accompanied by a minimum value of Q of around 2 for the sample annealed at 460 °C. These variations are related to the progress of nanocrystalization. The properties achieved are among the best reported for magnetomechanical applications.     

One-pot synthesis of magnetic,macro/mesoporous bioactive glasses for bone tissue engineering

Abstract

Magnetic and macro/mesoporous bioactive glasses were synthesized by a one-pot method via a handy salt leaching technique. It was identified to be an effective and simple synthetic strategy. The non-ionic triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123), was used as the structure directing agent for mesoporous structure but also as the reductant to reduce the iron source into magnetic iron oxide. The prepared materials exhibited excellent super-paramagnetic property with interconnected macroporous (200–300 μm) and mesoporous (3.4 nm) structure. Furthermore, their outstanding drug storage/release properties and rapid (5) induction of hydroxyapatite growth ability were investigated after immersing in simulated body fluid solution at 37 °C. Notably, the biocompatibility assessment confirmed that the materials obtained presented good biocompatibility and enhanced adherence of HeLa cells. Herein, the novel materials are expected to have potential application for bone tissue engineering.     

Annealing of shear bands in metallic glasses

Shear bands introduced into the as-quenched metallic glass alloy, Metglas^R 2826 (Fe₄₀Ni₄₀P₁₄B₆), were etched by immersion in a solution of CUS04 and HCI. Elimination of the etchability property through isothermal annealing had an apparent activation enthalpy of 250 kJ mol^–1, similar to that of stress relaxation. Direct microscopic observations indicated that the etching of shear bands may be a result of stress corrosion cracking. The electrochemical etchability of shear bands in the nickel-based alloy, BNi₂ (Ni_68.8Cr_6.6Fe_2.6B_14.1Si_7.9), polarized in a solution of perchloric acid and acetic acid at 12° C, could also be eliminated by thermal annealing. The loss of etchability had an apparent activation enthalpy of 580 kJ mol^–1, a value indicative of more complex atomic rearrangements taking place within the deformed material. Finally, shear bands introduced into the as-received BNi₂ material retained the ability to reverse shear after heat treatment at temperatures in the range of 192 to 375° C even if the electrolytic etchability was apparently diminished.     

Formation of MgNiPr bulk metallic glasses in air

The Mg–Ni–Pr bulk metallic glasses (BMGs) can be easily cast into glassy rods up to 3 mm in diameter in argon and air atmosphere. The underlying mechanism for the unusual oxygen resistance during the preparation process and high glass forming ability of the alloy are investigated and discussed.     

Application of Fe-based metallic glasses in wastewater treatment

This work pioneered the use of the Fe₇₈Si₉B₁₃ metallic glass ribbons in wastewater treatment. Fe₇₈Si₉B₁₃ metallic glass was employed to remediate wastewater contaminated with a mixture of organic dyes. The removal rate of chemical oxygen demand (COD) with Fe₇₈Si₉B₁₃ metallic glass and metallic Fe⁰ was up to 23 ± 0.93% in 30 min and 21 ± 0.67% with in 45 min, respectively. The dosage of Fe-based metallic glass was only 1/25 of that of metallic Fe⁰ to obtain equivalent effects. The mechanism of wastewater treatment through Fe-based metallic glasses is discussed.     

高熵非晶合金耐腐蚀性能研究进展

高熵非晶合金是近年来发展起来的一种新型合金材料,因其兼具高熵合金和非晶合金优异的力学性能、耐腐蚀性能、磁性能等功能特性,引发了众多学者的广泛关注。本文简述了高熵非晶合金的含义与特点,介绍了高熵非晶材料的制备方法及组织与性能;归纳了该类材料的耐蚀机理与耐腐蚀性能的最新研究成果;展望了采用机器学习助力设计高熵非晶合金的新范式,并指出探究工况环境下的腐蚀失效机制、完善高熵非晶合金微观耐蚀机理与优化相关制备工艺是该材料广泛应用的前提条件。针对高熵非晶合金的开发及其耐腐蚀性开展的应用基础研究,将为我国海洋事业的“远洋化、深海化”提供先进的技术支撑和材料保障。     

Applicability of FMR for crystallization studies in metallic glasses

It has been shown theoretically that the peak-to-peak ferromagnetic resonance (FMR) line-width (H _pp) should be proportional to the volume fraction (f) of the crystalline phase formed during annealing in ferromagnetic glasses. However, in the case of zero-magnetostrictive cobalt-based glasses (=0), H _pp should remain constant due to very low values of anisotropy. In Co₆₈Fe₄Mo₁Si₁₇B₁₀ glass (=0), H _pp has been found to remain unaffected upon progressive crystallization. In Fe₆₅Cr₈B₂₇ glass, H _pp has been found to be linearly proportional tof. Using this dependence, the activation energy of crystallization (E _a) has been calculated. The value ofE _a obtained from the FMR technique (248 kJ mol^–1) agrees quite well with those from DTA studies using Kissinger's or Ozawa's technique.     

Ultrasound-velocity measurement of strain in metallic polycrystals

During extension tests of metallic polycrystals, in situ measurement of ultrasound velocity (USV, V _US ) was carried out for the plastically deforming metallic polycrystalline specimens. USV has been found to depend on the plastic strain or acting stress of plastic flow. The complicated form of these dependencies is discussed in the context of the concept of evolution of lattice defects. V _US is shown to be associated with the multistage nature of the plastic flow curve. This allows plastic flow stages to be recognised with a higher degree of certainty. Thus the linear stage of work hardening has been separated for Al polycrystals by the procedure of USV measurement and certain peculiarities of plastic strains localisation as associated with USV variation have been investigated. Received: 2 April 2001 / Accepted: 24 May 2001     

Nucleation kinetics of primary crystallization products in FeSiB metallic glasses

Three iron-based metallic glasses in the Fe_96–x Si₄B _x series were examined after various dynamic and isothermal annealing treatments. The number and type of the primary crystallization products formed in these alloys were determined as functions of time and temperature, and the results compared with theoretical models. It has been found that, for certain alloys, a proportion of the primary -iron crystals in the structure are nucleated by particles of the metastable Fe₃B phase. The transformation kinetics of these composite crystals are different from those which do not contain an Fe₃B core, suggesting different nucleation mechanisms for the two types of crystal.     

Crystallization of stable and metastable eutectics in FeSiB metallic glasses

Two iron-based metallic glasses, Fe₇₈Si₉B₁₃ and Fe₇₈Si₁₀B₁₂, have been examined after isothermal annealing at different temperatures and it has been found that both stable and metastable eutectics can crystallize simultaneously during the annealing process. At low temperatures, the majority of the eutectic cells in the structure consist of -iron and the stable Fe₂B phase with a lesser amount of the -iron and metastable Fe₃B eutectic, whereas at higher temperatures the metastable eutectic predominates. It is suggested that these observations may be explained in terms of the presence of overlapping coupled zones of both the stable and metastable eutectics in the phase diagram.     

Role of minor alloying additions in formation of bulk metallic glasses: A Review

Minor alloying addition or microalloying technology has already shown dramatic effects on glass formation and thermal stability of bulk metallic glasses (BMGs). This paper intends to provide a comprehensive review of recent developments of this technology in the field of BMGs. The beneficial effects of minor alloying additions on the glass formation and the thermal stability of BMGs will be summarized and analyzed. In addition, principles and guidelines for future application of this technology will also be proposed.