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In general, findings in this study raised the curtain for the potential application of BMGs as future candidates for stent applications. Vascular stents are medical devices typically used to restore the lumen of narrowed or clogged blood vessel. Despite the clinical success of metallic materials in stent-assisted angioplasty, post-surgery complications persist due to the mechanical failures, corrosion, and in-stent restenosis of current stents.

To overcome these hurdles, strategies including new designs and surface functionalization have been exercised. In addition, the development of new materials with. The structural properties of Zr-based bulk metallic glasses subjected to high pressure torsion at different temperatures. X-ray diffraction, transmission electron microscopy were used to determine peculiarities of the modified structure. Analysis of fracture surfaces, nanohardness measurements were conducted to investigate the influence of structural changes on mechanical behavior of processed samples.

Pair distribution function study and mechanical behavior of as-cast and structurally relaxed Zr-based bulk metallic glasses. Fan, Cang; Liaw, P. Contrary to reported results on structural relaxation inducing brittleness in amorphous alloys, the authors found that structural relaxation actually caused an increase in the strength of Zr55Cu35Al10 bulk metallic glass BMG without changing the plasticity.

Only a small portion of the atom pairs was found to change to more dense packing. The concept of free volume was defined based on the PDF and RMC studies, and the mechanism of mechanical behavior was discussed. Zr55Cu30Al10Ni5 bulk metallic glass and its composites were prepared by suction casting into a copper mold.

The wear mechanism of both the metallic glass and its composite is abrasive wear. The mechanism of crystalline phase-dependent tribological properties of the composite was discussed based on the wear track and mechanical properties in the present work. The wear behavior of Zr55Cu30Al10Ni5 BMG and its composite indicates that a good combination of the toughness and the hardness can make the composite be well wear resistant. Dual self-organised shear banding behaviours and enhanced ductility in phase separating Zr-based bulk metallic glasses.

Zhang, Z. The multiplication and interaction of self-organised shear bands often transform to a stick-slip behaviour of a major shear band along the primary shear plane, and ultimately the major shear band becomes runaway and terminates the plasticity of bulk metallic glasses BMGs. The formation of multi-step phase separation, being mainly governed by nucleation and growth, results in the microstructural inhomogeneity on a wide range of length-scales and leads to obviously macroscopic and repeatable ductility.

The good deformability can be attributed to two mechanisms for stabilizing shear banding process, i. The two mechanisms could come into effect in the intermediate stable and later plastic deformation regime, respectively. Our findings provide a possibility to enhance the shear banding stability over the whole plastic deformation through a proper design of microstructure heterogeneities. Effects of chemical composition and test conditions on the dynamic tensile response of Zr-based metallic glasses. Wang, F.

The effects of impact velocity and temperature on the dynamic mechanical behavior of two bulk metallic BMG alloys with slightly different elemental compositions Zr55Cu30Ni5Al30 and Zr46Cu38Ag8Al38 have been investigated. The samples impacted steel extrusion dies which subjected the bullets to high strains at relatively high strain-rates. It was found that shear banding was the dictating mechanism responsible for the fracture of all BMGs.

The influence of Sc addition on the welding microstructure of Zr-based bulk metallic glass : The stability of the amorphous phase. Anomalous shear band characteristics and extra-deep shock-affected zone in Zr-based bulk metallic glass treated with nanosecond laser peening. The effects of nanosecond laser peening on Zr 41 Ti 14 Cu The peening treatment produced an extra-deep shock-affected zone compared to crystal metal. As opposed to the conventional shear bands, numerous arc shear bands appeared and aggregated in the vertical direction of the laser beam, forming basic units for accommodating plastic deformation.

The arc shear bands exhibited short and discrete features near the surface of the material, then grew longer and fewer at deeper peened layer depths, which was closely related to the laser shock wave attenuation. An energy dissipation model was established based on Hugoniot Elastic Limit and shear band characteristics to represent the formation of an extra-deep shock-affected zone. The results presented here suggest that the bulk modification of metallic glass with a considerable affected depth is feasible.

Further, they reveal that nanosecond laser peening is promising as an effective approach to tuning shear bands for improved MGs ductility. In this paper, a new materials platform, utilizing the amorphous microstructure of bulk metallic glasses BMGs and the versatility of ion implantation, was developed for the fundamental investigation of cell responses to substrate-rigidity variations in the gigapascal modulus range, which was previously unattainable with polymeric materials. Surface softening was achieved due to the formation of nanobubble-doped transitional zones in the Zrbased BMG substrate.

Cell adhesion and actin filaments were found to be less established on less stiff surfaces, especially on the surface with an elastic modulus of 51 GPa. Cell growth appeared to be affected by surface mechanical properties. A lower stiffness was generally related to a higher growth rate. Findings in this study broadened our fundamental understanding concerning the mechanosensing of bone cells on stiff substrates. It also suggests that surface mechano-engineering of metallic materials could be a potential strategy to promote osseointegration of such materials for bone-implant applications.

Further investigations are proposed to fine tune the ion implantation variables in order to further distinguish the surface-mechanical effect on bone-forming cell activities from the contributions of other surface properties. Through high-energy x-ray diffraction and atomic pair density function analysis we find that Zr-based metallic alloy, heated to the supercooled liquid state under hydrostatic pressure and then quenched to room temperature, exhibits a distinct glassy structure.

The PDF indicates that the Zr-Zr distances in this glass are significantly reduced compared to those quenched without pressure. Annealing at the glass transition temperature at ambient pressure reverses structural changes and the initial glassy state is recovered.

References

This result suggests that pressure causes a liquid-to-liquid phase transition in this metallic alloy supercooled melt. Such a pressure induced transition is known for covalent liquids, but has not been observed for metallic liquids. The High Pressure Quenched glasses are stable in ambient conditions after decompression. Synchrotron x-ray scattering investigations of oxygen-induced nucleation in a Zr-based glass -forming alloy. The samples crystallized into either a primitive tetragonal phase or the so-called fcc 'big cube' phase in a glassy matrix.

A subsequent discussion on the role of oxygen in heterogeneous nucleation in Zr-based bulk metallic glasses is presented. Effect of multiple alloying elements on the glass -forming ability, thermal stability, and crystallization behavior of Zr-based glass -forming alloys were studied in the present work. We investigated the effect of complete or partial substitution of Ti and Ni with similar early and late transition metals , respectively, on the glass -forming ability and crystallization behavior of the Zr50Ti10Cu20Ni10Al10 alloy.

Poor correlation was observed between different parameters indicating the glass -forming ability and the critical size of the obtained glassy samples. Importance of the width of the crystallization interval is emphasized. The kinetics of primary crystallization, i. Thus, it is difficult to estimate the glass -forming ability only on the basis of the empirical parameters not taking into account the crystallization behavior and the crystallization interval. Characterisation of metallic glass incorporated Zircaloy-2 weldments. In this study the effect of incorporation of Zr based Fe and Ni bearing metallic glass in spot welds in Zircaloy components has been examined.

Metallic Glass

A comparison of strength and microstructure of the welded joint with and without glass has been carried out. The welded joint with metallic glass has been found to be stronger than the one without metallic glass. The microstructure of the welded region with metallic glass has been found to comprise a large region having martensite. This large martensitic region has also been found to have considerable amount of excess solute Fe, Ni. The higher strength of the weld with metallic glass seems to originate due to solid solution strengthening, small grain size and the presence of martensitic structure over a large region.

Metallic glass composition. A metallic glass alloy that is either iron-based or nickel-based or based on a mixture of iron and nickel, containing lesser amounts of elements selected from the group boron, silicon carbon and phosphorous to which is added an amount of a ductility enhancing element selected from the group cerium, lanthanum, praseodymium and neodymium sufficient to increase ductility of the metallic glass upon annealing.

Recently, Zr-based metal organic frameworks MOFs were shown to be among the fastest catalysts of nerve-agent hydrolysis in solution. Here, we report a detailed study of the adsorption and decomposition of a nerve-agent simulant, dimethyl methylphosphonate DMMP , on UiO, UiO, MOF, and NU using synchrotron-based X-ray powder diffraction, X-ray absorption, and infrared spectroscopy, which reveals key aspects of the reaction mechanism. The diffraction measurements indicate that all four MOFs adsorb DMMP introduced at atmospheric pressures through a flow of helium or air within the pore space.

Our experimental probes into the mechanism of adsorption and decomposition of chemical warfare agent simulants on Zr-based MOFs open new opportunities in rational design of new and superior decontamination materials. Zr-based metal organic frameworks MOFs have been recently shown to be among the fastest catalysts of nerve-agent hydrolysis in solution. We report a detailed study of the adsorption and decomposition of a nerve-agent simulant, dimethyl methylphosphonate DMMP , on UiO, UiO, MOF, and NU using synchrotron-based X-ray powder diffraction, X-ray absorption, and infrared spectroscopy, which reveals key aspects of the reaction mechanism.

These experimental probes into the mechanism of adsorption and decomposition of chemical warfare agent simulants on Zr-based MOFs open new opportunities in rational design of new and superior decontamination materials. The dynamic pore systems and high surface areas of flexible metal -organic framework materials make them excellent candidates to be used in different kinds of adsorption processes.

However, the adsorption and desorption behaviors of therapeutic drugs on metal -organic frameworks in solution are not fully developed. Here, we systematically investigated the adsorption and desorption behaviors of a typical therapeutic drug, verapamil, over several Zr-based metal -organic frameworks [e.

These Zr-based materials had also been coated at the surface with filter papers for the analysis of various drugs and proteins in the process of paper spray mass spectrometry. Ni-Fe- Zr based Metallic glassy ribbons were prepared by melt spinning technique. The sealed metallic glassy ribbons were nano-crystallized at K for varying periods of time. The temperature dependence of the electrical resistivity of the nano-crystallized samples had been investigated over the temperature range K.

The crystallized ribbons at K for periods for less than 4 hours displayed insulating electrical behavior like at low temperatures, while those annealed for more than 4 hours showed metallic behavior like. Nonlinear I-V characteristics were also observed at low temperatures for samples annealed for less than four hours.

Microstructural development at weld interface between Zr-based glassy alloy and stainless steel by resistance microwelding. Zr-based bulk metallic glasses are expected to be welded to conventional structural alloys. Dissimilar welding of metallic glasses to stainless steel was carried out by resistance microwelding. The metallurgical analysis of the weld interface revealed the welding mechanism. A thin reaction layer was formed between the two liquid materials. The melting of stainless steel should be limited to obtain sound joints. Recent advances in bulk metallic glasses for biomedical applications.

With a continuously increasing aging population and the improvement of living standards, large demands of biomaterials are expected for a long time to come. Further development of novel biomaterials, that are much safer and of much higher quality, in terms of both biomedical and mechanical properties, are therefore of great interest for both the research scientists and clinical surgeons. Compared with the conventional crystalline metallic counterparts, bulk metallic glasses have unique amorphous structures, and thus exhibit higher strength, lower Young's modulus, improved wear resistance, good fatigue endurance, and excellent corrosion resistance.

For this purpose, bulk metallic glasses BMGs have recently attracted much attention for biomedical applications. This review discusses and summarizes the recent developments and advances of bulk metallic glasses , including Ti-based, Zr-based , Fe-based, Mg-based, Zn-based, Ca-based and Sr-based alloying systems for biomedical applications. Bulk metallic glasses BMGs , also known as amorphous alloys or liquid metals , are relative newcomers in the field of biomaterials. They have gained increasing attention during the past decades, as they exhibit an excellent combination of properties and processing capabilities desired for versatile biomedical implant applications.

Besides, the critical analysis and in-depth discussion on the current status, challenge and future development of biomedical BMGs are included. Cluster-assembled metallic glasses. A bottom-up approach to nanofabricate metallic glasses from metal clusters as building blocks is presented. Considering metallic glasses as a subclass of cluster-assembled materials, the relation between the two lively fields of metal clusters and metallic glasses is pointed out. Deposition of selected clusters or collections of them, generated by state-of-the-art cluster beam sources, could lead to the production of a well-defined amorphous material.

In contrast to rapidly quenched glasses where only the composition of the glass can be controlled, in cluster-assembled glasses , one can precisely control the structural building blocks. Comparing properties of glasses with similar compositions but differing in building blocks and therefore different in structure will facilitate the study of structure—property correlation in metallic glasses. This bottom-up method provides a novel alternative path to the synthesis of glassy alloys and will contribute to improving fundamental understanding in the field of metallic glasses.

It may even permit the production of glassy materials for alloys that cannot be quenched rapidly enough to circumvent crystallization. Additionally, gaining deeper insight into the parameters governing the structure—property relation in metallic glasses can have a great impact on understanding and design of other cluster-assembled materials. Quinary metallic glass alloys. At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than The composition is constrained such that the atomic percentage of iron is less than 10 percent.

The alloy composition formula is: Zr,Hf. Influence of thin-film metallic glass coating on fatigue behavior of bulk metallic glass : Experiments and finite element modeling. The results of finite-element modeling FEM revealed a delay in the shear-band nucleation and propagation in TFMG-coated samples under applied cyclic-loading. Cavitation instability in bulk metallic glasses. Recent experiments have shown that fracture surfaces of bulk metallic glasses BMGs usually exhibit an intriguing nanoscale corrugation like fractographic feature mediated by nanoscale void formation.

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We attribute the onset of this nanoscale corrugation to TTZs tension transformation zones mediated cavitation. In our recent study, the spall experiments of Zr-based BMG using a single-stage light gas gun were performed. To uncover the mechanisms of the spallation damage nucleation and evolution, the samples were designed to be subjected to dynamic tensile loadings of identical amplitude but with different durations by making use of the multi-stress pulse and the double-flyer techniques. It is clearly revealed that the macroscopic spall fracture in BMGs originates from the nucleation, growth and coalescence of micro-voids.

Then, a microvoid nucleation model of BMGs based on free volume theory is proposed, which indicates that the nucleation of microvoids at the early stage of spallation in BMGs is resulted from diffusion and coalescence of free volume. Furthermore, a theoretical model of void growth in BMGs undergoing remote dynamic hydrostatic tension is developed. The critical condition of cavitation instability is obtained. It is found that dynamic void growth in BMGs can be well controlled by a dimensionless inertial number characterizing the competition between intrinsic and extrinsic time scales.

To unveil the atomic-level mechanism of cavitation, a systematic molecular dynamics MD simulation of spallation behaviour of a binary metallic glass with different impact velocities was performed. It is found that micro-void nucleation is determined TTZs while the growth is controlled by shear transformation zones STZs at atomic scale. Mechanical rejuvenation in bulk metallic glass induced by thermo-mechanical creep. Using high energy X-ray diffraction we studied the temperature, stress, and time effect on structural changes in a Zr-based bulk metallic glass induced by thermo-mechanical creep.

Pair distribution functions obtained from two-dimensional diffraction patterns show that thermo-mechanical creep induces structural disordering, but only when the stress beyond a threshold is applied. A similar threshold behavior was observed for anelastic strain. We conclude that anelastic creep strain induces rejuvenation, whereas plastic strain does not. Fracture behaviors under pure shear loading in bulk metallic glasses. Pure shear fracture test, as a special mechanical means, had been carried out extensively to obtain the critical information for traditional metallic crystalline materials and rocks, such as the intrinsic deformation behavior and fracture mechanism.

However, for bulk metallic glasses BMGs , the pure shear fracture behaviors have not been investigated systematically due to the lack of a suitable test method. Here, we specially introduce a unique antisymmetrical four-point bend shear test method to realize a uniform pure shear stress field and study the pure shear fracture behaviors of two kinds of BMGs, Zr-based and La-based BMGs. All kinds of fracture behaviors, the pure shear fracture strength, fracture angle and fracture surface morphology, are systematically analyzed and compared with those of the conventional compressive and tensile fracture.

Our results indicate that both the Zr-based and La-based BMGs follow the same fracture mechanism under pure shear loading, which is significantly different from the situation of some previous research results. Our results might offer new enlightenment on the intrinsic deformation and fracture mechanism of BMGs and other amorphous materials.

Glass formation of a liquid undercooled below its melting temperature requires the complete avoidance of crystal nucleation and subsequent crystal growth. Even though they are not part of the glass formation process, a detailed knowledge of both processes involved in crystallization is mandatory to determine the glass -forming ability of metals and metallic alloys. In the present work, methods of containerless processing of drops by electrostatic and electromagnetic levitation are applied to undercool metallic melts prior to solidification.

Heterogeneous nucleation on crucible walls is completely avoided giving access to large undercoolings. A freely suspended drop offers the additional benefit of showing the rapid crystallization process of an undercooled melt in situ by proper diagnostic means. As a reference, crystal nucleation and dendrite growth in the undercooled melt of pure Zr are experimentally investigated. The experimental results are analyzed within classical nucleation theory and models of dendrite growth.

The findings give detailed knowledge about the nucleation-undercooling statistics and the growth kinetics over a large range of undercooling. Four-point-bending-fatigue behavior of the Zr-based Vitreloy bulk metallic glass. The fatigue lifetimes in four-point bending were found to be greater than those reported in uniaxial testing. However, the fatigue-endurance limit found in four-point bending was slightly less than that reported for uniaxial fatigue.

Thus, the significant differences between fatigue studies in the literature are not likely due to this difference in testing geometry. The four-point-bending-fatigue performance of the Vit alloy was found to be greater than most BMGs and similar to the M high-strength steel and other crystalline alloys in spite of not being 'perfectly amorphous. Elastic Heterogeneity in Metallic Glasses. Therefore it may appear obvious that a metallic glass deforms elastically.

We suggest that this anelastic portion represents residual liquidity in the glassy state. This study aimed to perform in vivo evaluations of Zr65Al7. In the study for intramedullary implants, osteotomies of the femoral bones were performed in male Wistar rats and were stabilized with Zr65Al7. In the study for bone surface implants, Zr65Al7. Local effects on the surrounding soft tissues of the implanted BMGs were assessed by histological observation.

In the study for intramedullary implants, bone healing after osteotomy was assessed by peripheral quantitative computed tomography QCT and mechanical tests. Histological observation showed no findings of the biological effects. In conclusion, Zr-based BMGs are promising for osteosynthesis devices that are eventually removed. Preparation, glass forming ability, crystallization and deformation of zirconium, hafnium -copper-nickel-aluminum-titanium-based bulk metallic glasses.

Multicomponent Zr-based bulk metallic glasses are the most promising metallic glass forming systems. They exhibit great glass forming ability and fascinating mechanical properties, and thus are considered as potential structural materials. One potential application is that they could be replacements of the depleted uranium for making kinetic energy armor-piercing projectiles, but the density of existing Zr-based alloys is too low for this application.

Based on the chemical and crystallographic similarities between Zr and Hf, we have developed two series of bulk metallic glasses with compositions of HfxZr1-x Remarkably increased density and improved mechanical properties have been achieved in these alloys. In these glasses , Hf and Zr play an interchangeable role in determining the short range order. Although the glass forming ability decreases continuously with Hf addition, most of these alloys remain bulk glass -forming. Recently, nanocomposites produced from bulk metallic glasses have attracted wide attention due to improved mechanical properties.

However, their crystalline microstructure the grain size and the crystalline volume fraction has to be optimized. We have investigated crystallization of Zr, Hf -based bulk metallic glasses , including the composition dependence of crystallization paths and crystallization mechanisms. Our results indicate that the formation of high number density nanocomposites from bulk metallic glasses can be attributed to easy nucleation and slowing-down growth processes, while the multistage crystallization behavior makes it more convenient to control the microstructure evolution.

Metallic glasses are known to exhibit unique plastic deformation behavior. At low temperature and high stress, plastic flow is localized in narrow shear bands. Macroscopic investigations of shear bands e. Thermal rejuvenation in metallic glasses. Structural rejuvenation in metallic glasses by a thermal process i. An increase in the potential energy, a decrease in the density, and a change in the local structure as well as mechanical softening were observed after thermal rejuvenation. A rejuvenation map was constructed using these two parameters. Since the thermal history of metallic glasses is reset above 1.

The glassy structure transforms into a more disordered state with the decomposition of icosahedral short-range order within this temperature range. Therefore, a new glassy structure rejuvenation depending on the subsequent quenching rate is generated. This behavior probably originates from disordering in the weakly bonded loosely packed region.

This study provides a novel approach to improving the mechanical properties of metallic glasses by controlling their glassy structure. Spallation behaviour of a Zr-bulk metallic glass. Plate impact experiments have been conducted on a Zr-based bulk metal glass BMG using a single stage light gas gun. To understand the spallation process of the material, samples were subjected to dynamic tensile loadings of the same amplitude but different durations.

Fractographs of spallation surface and fracture features were characterized and the fracture mechanism of different regions of the spallation surface was discussed. Morphology of the spallation surface in the Zr-BMG exhibited a typical equiaxial cellular pattern and porous microstructure. These experiments revealed that, subjected to hydro-tensile stresses, the microdamage of the spallation occurred in the Zr-BMG is microvoids; the spallation in the Zr-BMG is resulted from nucleation, growth and coalescence of microvoids; and the time needed for these microvoids nucleation is less than ns with a stress amplitude of 3.

Bulk metallic glasses BMGs represent an emerging class of materials that offer an attractive combination of properties, such as high strength, low modulus, good fatigue limit, and near-net-shape formability.

The BMGs have been explored in mechanical, chemical, and magnetic applications. However, little research has been attracted in the biomedical field. In this work, we study the potential of BMGs for the orthopedic repair and replacement. We report the biocompatibility study of zirconium Zr -based solid BMGs using mouse osteoblast cells.

Cell attachment, proliferation, and differentiation are compared to Ti-6Al-4V, a well-studied alloy biomaterial. Our in-vitro study has demonstrated that cells cultured on the Zr-based BMG substrate showed higher attachment, alkaline phosphatase activity, and bone matrix deposition compared to those grown on the control Ti alloy substrate. Cytotoxicity staining also revealed the remarkable viability of cells growing on the BMG substrates.

Magnetic antenna using metallic glass. A lightweight search-coil antenna or sensor assembly for detecting magnetic fields and including a multi-turn electromagnetic induction coil wound on a spool type coil form through which is inserted an elongated coil loading member comprised of metallic glass material wrapped around a dielectric rod. The dielectric rod consists of a plastic or a wooden dowel having a length which is relatively larger than its thickness so as to provide a large length-to-diameter ratio.

A tri-axial configuration includes a housing in which is located three substantially identical mutually orthogonal electromagnetic induction coil assemblies of the type described above wherein each of the assemblies include an electromagnetic coil wound on a dielectric spool with an elongated metallic glass coil loading member projecting therethrough.

Production of glass or glass -ceramic to metal seals with the application of pressure. In a process for preparing a glass or glass -ceramic to metal seal comprising contacting the glass with the metal and heat-treating the glass and metal under conditions whereby the glass to metal seal is effected and, optionally, the glass is converted to a glass -ceramic, an improvement comprises carrying out the heat-treating step using hot isostatic pressing.

U-based metallic glasses with superior glass forming ability. By using Al as the third and B as the fourth but minor alloying elements for the U The improvement in GFA would result from denser atomic packing in the undercooled liquids due to the presence of small B atoms. Some U-Co-Al -B glasses showed corrosion resistance comparable to that of U64Co34Al2 glass , known for premium anti-corrosive performance among the unveiled U-based glasses.

Origin of anomalous inverse notch effect in bulk metallic glasses. Understanding notch-related failure is crucial for the design of reliable engineering structures. However, substantial controversies exist in the literature on the notch effect in bulk metallic glasses BMGs , and the underlying physical mechanism responsible for the apparent confusion is still poorly understood.

Here we investigate the physical origin of an inverse notch effect in a Zr-based metallic glass , where the tensile strength of the material is dramatically enhanced, rather than decreased as expected from the stress concentration point of view , by introduction of a notch. Our experiments and molecular dynamics simulations show that the seemingly anomalous inverse notch effect is in fact caused by a transition in failure mechanism from shear banding at the notch tip to cavitation and void coalescence. Based on our theoretical analysis, the transition occurs as the stress triaxiality in the notched sample exceeds a material-dependent threshold value.

Our results fill the gap in the current understanding of BMG strength and failure mechanism by resolving the conflicts on notch effects and may inspire re-interpretation of previous reports on BMG fracture toughness where pre-existing notches were routinely adopted. Effective temperature dynamics of shear bands in metallic glasses.

We study the plastic deformation of bulk metallic glasses with shear transformation zone STZ theory, a physical model for plasticity in amorphous systems, and compare it with experimental data. In STZ theory, plastic deformation occurs when localized regions rearrange due to applied stress and the density of these regions is determined by a dynamically evolving effective disorder temperature.

We compare the predictions of STZ theory to experiments that explore the low-temperature deformation of Zr-based bulk metallic glasses via shear bands at various thermal temperatures and strain rates. By following the evolution of effective temperature with time, strain rate, and temperature through a series of approximate and numerical solutions to the STZ equations, we successfully model a suite of experimentally observed phenomena, including shear-band aging as apparent from slide-hold-slide tests, a temperature-dependent steady-state flow stress, and a strain-rate- and temperature-dependent transition from stick-slip serrated flow to steady-sliding nonserrated flow.

We find that STZ theory quantitatively matches the observed experimental data and provides a framework for relating the experimentally measured energy scales to different types of atomic rearrangements. A nanoscale Zr-based fluorescent metal -organic framework for selective and sensitive detection of hydrogen sulfide. Hydrogen sulfide H2S has been commonly viewed as a gas signaling molecule in various physiological and pathological processes. However, the highly efficient H2S detection still remains challenging. This MOF-based probe also exhibited fast response 10 s and high sensitivity with a detection limit of 6.

Moreover, this constructed MOF featured water-stability, nanoscale nm and low toxicity, which made it a promising candidate for biological H2S sensing. Metallic glasses are metallic alloy systems with disordered atomic structure. Due to their unique amorphous structure, they exhibit an extraordinary set of properties that are ideal for a wide variety of applications ranging from electrical transformers, armor-piercing projectiles, sporting goods and fuel cells to precision gears for micromotors.

Unfortunately, their unique structure also gives rise to significant limitations, such as limited ductility at room temperature due to rapid localization of plastic flow in shear bands. This study investigates the phenomenon of strain localization using both experimental and computational techniques.

On the experimental front, sample size effects on strength, plasticity and deformation modes were explored in a Zr-based bulk metallic glass via micron- and sub-micron scale compression testing. Specimens with diameters ranging from nm to a few microns were fabricated using Focused Ion Beam technique and were tested under uniaxial compression in a nanoindentation set-up with a flat punch tip. Effect of extrinsic factors like specimen geometry and machine stiffness on deformation behavior was discussed. Shear banding was shown to be more stable at this length scale than in macro-scale testing because of a smaller specimen to load frame stiffness ratio.

It was found that as the specimen size is reduced to below nm, the deformation mode changes from being discrete and inhomogeneous to more continuous flow including both localized and. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites. Wang, Z. Springer, pp. Maak C. Martinelli A. Meyer H. Michalchuk A. Mokhtari M. Ormstrup J. Pietsch P. Proudhon H. Quey R. Romedenne M. Schenk T. Shahzad S. Sun J. Voillot M. Wang Z. Weber H.

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Designing in situ and ex situ bulk metallic glass composites via spar…

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