Microstructure Of Glass Research Articles

Microstructure and properties of ultra-thick Fe-based metallic glass by twin-roll strip casting versus a traditional process

In this study, an ingenious twin-roll strip casting approach is described to process large-size Fe71Ni9P12B4.9Si2.5Cu0.6 amorphous ribbons. The 150 μm thick RT ribbon (novel process) characterized by a completely amorphous structure is 5 to 7 times thicker than the conventional Fe-based RS (conventional process) ribbon. The minimum cooling rates of the RS and RT ribbon were 1.78 × 106 and 5.58 × 105 K/s. The RT ribbon's excellent thermodynamic properties led to fine grain size and a high magnetic induction of 1.63 T. However, high internal stress led to a large magnetocrystalline anisotropy. The hardness of the two ribbons was similar at ∼1160 Hv. Moreover, the significant size effect led to a slight decrease in the fracture toughness of the RT ribbon. The impressive specifications, high impurity tolerance, and good properties of the RT ribbon render twin-roll strip casting promising for industrial applications.

Effect of substitution of ZrO2 by SnO2 on crystallization and properties of environment-friendly Li2O–Al2O3–SiO2 system (LAS) glass-ceramics

In this study, a transparent and environmentally friendly Li2O–Al2O3–SiO2 (LAS) glass-ceramic was prepared by melt-quenching and two-step heat treatment. The influence of the substitution amount of ZrO2 by SnO2 on the crystallization, microstructure, transparency, and mechanical properties of LAS glass and glass-ceramics was investigated by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Ultraviolet–visible Spectrophotometer, three-point bending strength test, and microhardness test. The results indicate that the main crystalline phase of LAS glass ceramics was a β-quartz solid solution when heat treated at 780 °C for 2 h and 870 °C for 1.5 h. When the substitution amount of ZrO2–SnO2 increased from 0.4 mol% to 2.5 mol%, the grain size and thermal expansion coefficient of LAS glass-ceramics first decreased and then increased, and the crystallinity first increased and then decreased. When the substitution amount of ZrO2–SnO2 was 0.8 mol%, the transparency of the LAS glass-ceramics was maximum, the bending strength was 96 MPa, and the Vickers hardness was 10.9 GPa.

Femtosecond Laser Assisted 3D Etching Using Inorganic-Organic Etchant.

Selective laser etching (SLE) is a technique that allows the fabrication of arbitrarily shaped glass micro-objects. In this work, we show how the capabilities of this technology can be improved in terms of selectivity and etch rate by applying an etchant solution based on a Potassium Hydroxide, water, and isopropanol mixture. By varying the concentrations of these constituents, the wetting properties, as well as the chemical reaction of fused silica etching, can be changed, allowing us to achieve etching rates in modified fused silica up to 820 μm/h and selectivity up to ∼3000. This is used to produce a high aspect ratio (up to 1:1000), straight and spiral microfluidic channels which are embedded inside a volume of glass. Complex 3D glass micro-structures are also demonstrated.

Glass-in-glass infiltration for 3D micro-optical composite components.

Chalcogenide glass exhibits a wide transmission window in the infrared range, a high refractive index, and nonlinear optical properties; however, due to its poor mechanical properties and low chemical and environmental stability, producing three-dimensional microstructures of chalcogenide glass remains a challenge. Here, we combine the fabrication of arbitrarily shaped three-dimensional cavities within fused silica molds by means of femtosecond laser-assisted chemical etching with the pressure-assisted infiltration of a chalcogenide glass into the resulting carved silica mold structures. This process enables the fabrication of 3D, geometrically complex, chalcogenide-silica micro-glass composites. The resulting products feature a high refractive index contrast that enables total-internal-reflection guiding and an optical quality roughness level suited for applications in the infrared.

Enhancement of the radiation resistance of cerium-containing fluorophosphate glasses through codoping with Sb2O3 and Bi2O3

The growing demand for radiation-resistant optical glasses for space and nuclear radiation applications has attracted significant research interest. However, radiation-resistant fluorophosphate glasses have been poorly studied. In this work, we report on the tailoring and performance of radiation-resistant fluorophosphate glasses that contained cerium through codoping with Sb2O3 and Bi2O3. The physical properties, optical properties, microstructure, and defects of fluorophosphate glasses were investigated using transmittance measurements, absorption measurements, as well as Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. The results showed that the radiation resistance of all codoped fluorophosphate glasses was better than the undoped cerium-containing fluorophosphate glasses after 10–250 krad(Si) irradiation. Especially in glasses doped with Bi2O3, the optical density increment at 385 nm was only 0.1482 after 250 krad(Si) irradiation. The CeO2 prevented the development of phosphate-related oxygen hole center (POHC) defects, whereas further codoping with Bi2O3 suppressed the formation of oxygen hole center (OHC) and POEC defects, reducing the breaking of phosphate chains caused by CeO2. Bi3+ is more likely than Sb3+ to change the valence, affecting the transition equilibrium of intrinsic defects and reducing the concentration of defects produced by irradiation. When codoping with Sb2O3 and Bi2O3, Bi2O3 does not enhance radiation resistance owing to the scission effect of Sb2O3 on the phosphate chain, which is not conducive to the radiation resistance of glasses. This indicates that the cerium-containing fluorophosphate glasses doped with Bi2O3 can effectively suppress the defects caused by irradiation and improve the radiation resistance of the glasses.

Effect of Co addition on the microstructure, thermal stability and anti-corrosion properties of AlNiZrYCox high-entropy metallic glass ribbons

In this current research, the effect of Co addition on the microstructure and anti-corrosion properties of equiatomic AlNiZrY high-entropy metallic glass (abbreviated to HE-MG) ribbons were investigated. Also, the thermal stability and crystallization activation energy of these HE-MG ribbons have been studied. Ribbons of composition (Al1/4Ni1/4Zr1/4Y1/4)100-xCox (x= 0, 5, 8, 12) were synthesized via arc-melting method and melt-spinning technique. By increasing the content of Co, we found that the melt-spun equiatomic AlNiZrY and Co-containing AlNiZrY HE-MG ribbons could still remain amorphous state. The thermal stability of ribbons were conducted by means of a differential scanning calorimeter (DSC), which suggested that the thermal stability of four kinds of HE-MG ribbons is higher than common Al-Ni-based amorphous alloys. The maximum apparent activation energy of crystallization through thermodynamic analysis at different heating rates can reach ∼630 kJ/mol for (Al1/4Ni1/4Zr1/4Y1/4)92Co8 HE-MG ribbons. The microstructure characterization of each HE-MG ribbon before and after one-day corrosion immersion was done by scanning electron microscopy (SEM). In order to evaluate the microhardness and corrosion resistance of the as-received HE-MG ribbons with and without the addition of Co, the microhardness measurements and the electrochemical corrosion tests in 3.5 wt.% NaCl solution were carried out. The results revealed that the average microhardness value of HE-MG ribbons are all above 470 HV0.1, regardless of whether the ribbons immersed in corrosive media for one-day immersion or not. The corrosion current density of (Al1/4Ni1/4Zr1/4Y1/4)88Co12 HE-MG ribbons is around 0.46 μA/cm2, which possesses the sterling anti-corrosion property and opens vital possibilities for the development of high-performance metal coatings under the condition of harsh marine environment.

The production technology of mineral soda alumina glass: A perspective from microstructural analysis of glass beads in Iron Age Taiwan.

Mineral soda alumina (m-Na-Al) glass is a common glass production group found around the Indo-Pacific region. In Iron Age Taiwan, its presence dates back to the early 1st millennium AD. This research discusses m-Na-Al glass beads excavated from Iron Age sites in Taiwan. No production sites for m-Na-Al have been found, but microstructural analysis suggests m-Na-Al glass appears to originate around South Asia and is exchanged widely. SEM-EDS and EPMA were used to analyse red, orange, yellow, green and blue m-Na-Al glass. The microstructure of the glass shows the presence of plagioclase and alkali feldspar relics in the glass, suggesting a low manufacturing temperature. Copper-based colourants are identified in red, orange, blue and green glass, while lead tin oxide is used in yellow and green glass. It appears that various types of copper-containing raw materials were procured by craftspeople, and a self-reduction process for producing red and orange glass is tentatively proposed. Additionally, the microstructure of yellow glass reveals different colouring paths were used. These results increase our understanding of the selection of raw materials, and provide an impetus for further research on the cross craft interaction between glass and copper production.

Microstructure, thermophysical, and mechanical properties of bulk glass prepared from molten lunar regolith simulant

To provide the base data for the high-temperature processing of lunar regolith in future space activities, the materials prepared by fully melting of lunar regolith simulant (LRS) rather than the sintering is thoroughly characterized in terms of microstructure, thermophysical, and mechanical properties. The obtained material is glass–ceramic derived from the crystallization of molten regolith through a cooling process. Thermal expansion coefficient lies within a range of 6.42 × 10-6 1/℃ to 9.82℃ × 10-6 1/℃ between reference temperature (30 ℃) and softening point (919 ℃), and the thermal conductivity and specific heat capacity are close to the concrete. At room temperature, the ultimate compressive strength and the flexural strength is 67.1 ± 31.9 MPa and 100.7 ± 31.3 MPa, respectively, which are much higher than that of the traditional cement on Earth. Presented treatment crafts give a rise to thermal coating fabrication, and the products can be used as architectural and functional materials for the construction, operation, and maintenance of future lunar bases.

Role of MgO in lowering glass transition temperature and increasing hardness of lithium silicate glass and glass-ceramics

The effect of variation of MgO (1.5, 4.5 and 7.5 mol%) content on glass structure, crystallization behavior, microstructure and mechanical properties in a Li2O–K2O–Na2O–CaO–MgO–ZrO2–Al2O3–P2O5–SiO2 glass system has been reported here. Increased amount of MgO enhanced the participation of Al2O3 as a glass network former along with [SiO4] tetrahedra, reducing the amount of non-bridging oxygen (NBO) and increasing bridging oxygen (BO) amount in glass. The increased BO in glass resulted in a polymerized glass structure which suppressed the crystallization and subsequently increased the crystallization temperature, bulk density, nano hardness, elastic modulus in the glasses as well as the corresponding glass-ceramics. MgO addition caused phase separation in higher MgO (7.5 mol%) containing glass system which resulted in larger crystals. The nano hardness (∼10 GPa) and elastic modulus (∼127 GPa) values were found to be on a much higher side in 7.5 mol% MgO containing glass-ceramics as compared to lower MgO containing glass-ceramics.

Contrast of color-changing metallic glasses reveals the glass properties beneath the surface

Recently, color-changing glasses have been developed from a series of Ce-based metallic alloys. The functionality originates from fast and spontaneous surface oxidation. In most cases, single-color glasses have been obtained, but in a few cases, multicolor glasses that have spatially-dependent color contrast have been found. The natural color contrast mostly results from the interference effects on the oxide layer. The present work investigates factors that influence and control the variable oxidation rate observed at different locations on the surface, and what manufacturing steps and processing history lead to the rate variation. It is found that cooling rate, residual strain, and precipitation in melt-spun ribbons are the effects controlling the oxidation rate giving the enhanced color contrast. Therefore, the final surface color contrast reflects the non-uniform distribution of enthalpy (glassy state), microstructure, and chemistry of the metallic glass beneath the surface. The inspection of natural color contrast also represents technologically useful method for early surface flaw detection in color-changing metallic glasses.

Correlation of parameters and microstructure of 3D printing bulk medical titanium-based metallic glass

Metallic glass has developed over the past few decades. To fabricate the metallic glass, high cooling rates (105 K/s) is needed to form the disorder atomic structure [1]. Because metallic glass has no grain boundary, its characteristics are superior to traditional crystalline materials, such as good wear resistance, and excellent corrosion resistance [2]. In the past few decades, most amorphous alloy systems can only be manufactured to a millimeter size, causing the application difficulties [3]. Due to development of 3D printing technology nowadays, it’s expected to manufacture metallic glass in a larger size due to the localized melting process with a high cooling rate. Due to the breakthrough in size, it can be applied to medical equipment such as scalpels, dental implants, and various implants in the future. However, the relationship between the materials, 3D printing process parameter, and microstructure evolution is still needed to be explored. Thus, in study, such relationship of Ti-based metallic glass is studied through changing parameters of scan speed and laser power to vary cooling rates and microstructure by Selective Laser Melting (SLM). The samples were examined through the X-ray diffractometer (XRD) and the scanning electron microscope (SEM) with energy disthispersive spectrometry (EDS). The composition variation and microstructure evolution during the 3D printing process was discussed in detail from the point of view of 3D printing parameter, molten pool behavior, and heat of mixing. Furthermore, the mechanical properties of metallic glass were investigated by using micro-indentation, which results showed further that the microstructure indirect effects hardness and young’s modulus of the alloys.

Microstructure and mechanical behavior evolution of Ti-based bulk metallic glass induced by sub-Tg isothermal annealing

In this study, the effects of sub-Tg isothermal annealing on the microstructure, mechanical and serrated flow behaviors of Ti33Zr30Cu9Ni5.5Be22.5 bulk metallic glass (BMG) were investigated. The change in free volume content of the BMG was characterized according to the structural relaxation enthalpy δHr and the onset structural relaxation temperature Tr, with the results indicating a monotonic decreasing trend of the free volume content with the extension in annealing time. A number of nanocrystals with a size of approximately 4 nm were precipitated on the glassy matrix when the annealing time was extended to 1.0 h, and then the size of these nanocrystals increased with further prolongation of the annealing time. Meanwhile, the room-temperature compressive plasticity of the Ti33Zr30Cu9Ni5.5Be22.5 BMG greatly improved from 1.4% to 4.2%, and the high strength was retained after annealing for 1.0 h, which can be largely attributed to the formation of the nanocrystals with the size of about 4 nm. With the extension of the annealing time, however, the further growth of the nanocrystals resulted in the degeneration of the compressive strength and the plasticity. The serrated rheology analysis revealed that the distribution histogram of the stress drop for the 1.0 h-annealed specimen represented a well characteristic of power-law distribution, whereas the 4.0 h-annealed showed a chaotic dynamics of jerk flow. Furthermore, the 1.0 h-annealed specimen possessed the lower average stress drop (12 MPa), formation energy per unit shear band (254.9 J/m2) and average shear band velocity (1.21 × 10−5 m s−1).

Aggregation-induced emission fluorophore doped phosphate glass: Toward light-emitting electrochemical cells

Light-emitting electrochemical cells (LECs) are an easy-to-fabricate electroluminescent device, which in its simplest manifestation comprises an electroluminescence organic fluorophore and electrolytes as the active layer sandwiched between two electrodes. The LEC exhibits poor operational stability, and the poor thermal stability of the electrolyte is a major cause of the instability. Because most of the electrolytes utilized in LEC are organic electrolytes (polymer and ionic liquids), the thermal stability is difficult to improve on a large scale. Therefore, in this work, we are devoted to preliminarily exploring the possibility of using an inorganic glass electrolyte for LEC application. Following this objective, organic fluorophore (π-extended phosphole sulfide 1) doped inorganic phosphate amorphous matrix was successfully synthesized using spark plasma sintering technology. The optical properties, microstructure, and electrochemical properties of the hybrid glass were investigated, respectively. The ionic conductivity of the glass host can reach 10−7 S/cm at room temperature, and the glass matrix contain aggregates of 1 of around 100 nm. Strong photoluminescence at 600 nm, characteristic of the organic fluorophore, was observed in the hybrid glass. The cyclic voltammetry performed on the hybrid glass shows a redox couple contribution of the organic fluorophore. The result suggests 1 can complete the exchange of electric charges in the inorganic glass electrolyte, which is one of the fingerprints of the transient phenomena of a LEC.

Role of Co content on the microstructure and anti-corrosion performance of high-hardness AlNiYCox high entropy metallic glasses

In the present paper, the role of Co content on phase structure, thermal stability and anti-corrosion performance of melt-spun (Al1/3Ni1/3Y1/3)100-xCox (x= 5, 8, 12, 15 and 20 at.%) high entropy metallic glasses has been investigated. The microstructure and average hardness of AlNiYCox alloy ribbons were characterized and detected using a scanning electron microscope (SEM) and Vickers-type hardness tester, respectively. The corrosion behavior in 3.5 wt% NaCl solution was tested through the conventional potentiodynamic polarization curves (Tafel curves) and electrochemical impedance spectroscopy (EIS). Results suggested that all kinds of high entropy metallic glass ribbons could remain amorphous nature and the crystallization onset temperature are all above 750 K. The average hardness value of each ribbon sample is more than 530 HV0.1 as well. With the increase of Co content, the corrosion resistance begins to enhance and then lowers gradually. When the Co content increases from 5 at.% to 20 at.%, it can result in a decrease of corrosion current density from 9.546 µA/cm2 of the (Al1/3Ni1/3Y1/3)95Co5 to 0.508 µA/cm2 of the (Al1/3Ni1/3Y1/3)92Co8 and 0.741 µA/cm2 of the (Al1/3Ni1/3Y1/3)80Co20 alloy ribbons. Therefore, it is assumed that adding appropriate content of Co element into (Al1/3Ni1/3Y1/3)100-xCox alloys can enhance ability to resist corrosion in 3.5 wt% NaCl solution. The ribbons with 8 at.% Co exhibited the excellent anti-corrosion performance in this current study.

Experimental investigation of deep-hole micro-drilling of glass using LIPAA process

ABSTRACT This paper aims to study the mechanism of glass deep-hole micro-drilling by the Laser-Induced Plasma-Assisted Ablation (LIPAA) process. The Micro-drilling of glass was studied under various laser intensities. Nd:YAG nanosecond pulsed laser with 12 ns pulse duration was used as the laser light source. Copper was used as the metal target for the experiments. It is shown that laser glass micro-drilling is divided into two ablation stages. In the first stage, ablation is done by the brittle failure of glass caused by the collision of plasma plume with the glass surface. Exertion of mechanical pressure is also an important factor in the first few laser shots. Due to mechanical failure, glass microstructure changes in the focal spot. Second stage ablation is directly conducted by the thermal mechanism through absorption of laser by the glass. The hole produced on the glass by thermal mechanism is free of cracks. Cylindricity and roundness of the hole are very desirable. Laser intensity plays a vital role in material removal rate, hole depth and diameter. The process can be used for high-speed deep-hole micro-drilling of transparent materials to laser with good surface integrity and high-aspect ratio.

Microstructure and mechanical evolution of Ti-based bulk metallic glass induced by deformation and isothermal annealing in supercooled liquid region

The effects of deformation and isothermal annealing in supercooled liquid region on the microstructure and room-temperature mechanical properties of the Ti33Zr30Cu9Ni5.5Be22.5 bulk metallic glass were systematically investigated. The results indicated that the thermally-deformed specimens exhibited denser structures and higher characteristic temperatures (Tg and Tx) than the annealed specimens at the corresponding temperature; however, this difference gradually decreased as the experimental temperature increased. Further, the thermally-deformed specimens exhibited higher yield and fracture strengths than the annealed specimens, whereas they exhibited similar plasticity. The deformed and annealed specimens precipitated some nanocrystals with a size of approximately 10 nm when the experimental temperature increased to 648 K, causing the rapid deterioration of their plasticity.

Evaluating the Microstructure of Photoluminescent Concrete Pavement Containing Strontium-Aluminate, Acrylic and Recycled Waste Glass

This paper constructs the photoluminescent concrete pavement (PhotoCP) mixing the photoluminescent material (Strontium-Aluminate) with recycled waste glass and transparent acrylic to visible the neighbourhood streets without streetlights. The non-destructive analyses of photoluminescent materials were conducted using the X-Ray Fluorescence, X-Ray diffraction, and Scanning Electron Microscopy instruments to understand the behaviour of atoms in photoluminescent materials when they interact with radiation. The compressive strength test examined the load bearing capacity of PhotoCP. A 30cm x 230cm test bed was constructed at a neighbourhood street in Peshawar, Pakistan to assess the impact of photoluminescent materials on lighting the neighbourhood street. The non-destructive analyses and compressive strength test show that PCP specimens have good interlocking capability, structural strength and durability. The testbed experiment observed the illuminance of PhotoCP for a period of 6 to 8 hours with highest lumen intensity of 1-3 lux from sunset to 8:30 pm.

Effect of alloying oxygen on the microstructure and mechanical properties of Zr-based bulk metallic glass

Due to the high solubility limit of oxygen in Zr, dissolution of oxygen in the Zr-based alloys is unavoidable. However, as an alloying element, the effect of oxygen on the microstructure and mechanical properties of monolithic Zr-based bulk metallic glasses (BMGs) is rarely reported. Here, we systematically investigated the evolution of microstructure and mechanical properties of monolithic Zr61Cu25Al12Ti2 BMGs with alloying oxygen content ranging from 650 at. ppm to 5600 at. ppm. With increasing oxygen content from 650 at. ppm to 3500 at. ppm, the compressive plasticity only decreased slightly, from 2.00±0.85% to 1.60±0.91%; however, it plunged to 0.77±0.33% when the oxygen content was further increased to 5600 at. ppm. The threshold oxygen content level for the ductile-brittle transition was revealed at 3500 at. ppm, and the embrittlement at high oxygen content is closely related with a number of changes in microstructure: sharply increases in the size of shear transformation zone (STZ) and in the degree of local ordering, including the imperfect ordered packing (IOP) atomic clusters and large medium-range ordering (MRO) domains. The above findings not only advance the understanding of the effect of alloying oxygen on the microstructure and mechanical properties, but also help to design Zr-based BMGs with excellent performance, promoting their wider commercial application.

Microstructure and performance of novel ductile FeNi-based metallic glasses

Fe-based bulk metallic glasses (BMGs) are of significant interest because of their superior magnetic and mechanical properties, but the plastic strain deficiency at room temperature restricts their application. In the present study, the effect of Ni content on thermal stability, soft magnetic properties and compressive plastic deformation was investigated in Fe80−xNixP12B4.9Si2.5Cu0.6 (x = 0, 3, 6, 9, 12, 15) BMGs. We discovered that the Ni-bearing BMGs exhibit strong GFA, good soft magnetic and mechanical properties, and high Tc, while the excessive Ni addition causes performance deterioration. The Fe71Ni9P12B4.9Si2.5Cu0.6 bulk glass exhibits high strength of about 3000 MPa and elevated plastic strain of 5.1%, together with high saturation magnetic induction of 1.51 T and low coercivity of 1.8 A/m. The Curie temperature up to 636 K was an intriguing finding. X-ray photoelectron spectroscopy results suggest that the brittle-ductile transition comes from the more s-like bonds between clusters because of the Ni addition. In terms of the inherent elastic nature, we consider that the high Poisson's ratio and the low G/K ratio of Ni lead to a large effective volume of the shear transition zone, which corresponds to the nucleation of shear bands. The significant compressive plastic behavior, large GFA and good soft magnetic properties indicated that the current Fe-based BMGs are promising for structural and magnetic functional applications.

Tailoring microstructure of metallic glass for delocalized plasticity by pressure annealing: Forward and inverse studies

As an extreme processing condition, pressure annealing has a great potential in tailoring the microstructure of metallic materials to improve their mechanical properties. Determining the process-microstructure-mechanical properties relationship with high-pressure and high-temperature is thus of scientific importance. Herein, we propose an approach of pressure annealing in tuning the structure and mechanical behavior of a prototype of Fe80P20 metallic glass (MG) through a combination of experiments, molecular dynamics (MD) simulations, and machine learning. The experimental results show that pressure annealing can induce structural rejuvenation and more distributed deformation in Fe80P20 MG. Inspired by this, forward studies from experiments to MD simulations are carried out to systematically investigate the effects of pressure annealing on the mechanical properties and microstructure of the Fe80P20 MG for a broad pressure and temperature range, followed by inverse studies from machine learning to experimental verification that enable us to capture the hiding structural feature affecting the mechanical behavior of pressure-annealed Fe80P20 MG. We demonstrate that pressure annealing can endow a MG having a transition of deformation mode from localized to delocalized, which is predominantly governed by pressure-annealing-induced variations in an atomic packing structure. Our work proposes a promising route for fine-tuning the mechanical properties of MGs, and provides insights into the current understanding of the relationship between the microstructure and mechanical behaviors of Fe80P20 MG with pressure annealing.