Glass-forming ability of high refractive index amorphous materials prepared by TiO2 and Nb2O5

The glass forming ability (GFA) of the Cu-Zr-Ag alloy system was investigated on the basis of the thermal stability, and the structural, thermodynamic and kinetic properties of the material. We changed the concentration of the alloys, as we departed from the Cu58Zr42 composition and produced three different eutectic points in the Cu-Zr-Ag ternary system, in accordance with the results published in the respective literature. We produced various test pieces of Cu-Zr-Ag amorphous alloys with different Ag contents (0-70%), by casting the material into wedge-shaped copper moulds. In such ternary alloy system there is only a limited concentration range where amorphous materials can be produced: in the event that the Ag content of the material exceeds 35 at%, no amorphous material structure will develop. In our experiment the maximum temperature range of the supercooled liquid region (ΔTx) was 75 K. The calculated four GFA parameter values are not in perfect harmony and fail to point out the optimal composition available; however, based on γ and the reciprocal value of ω, the best compositions from the GFA aspect are Cu42.5Zr37.5Ag20and Cu40Zr37.5Ag22.5. The decrease of the maximum thickness of the bulk metallic glasses is influenced more by the oxygen content than the composition changes within the Cu-Zr-Ag system.

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The Role of Casting Temperature in Preparation of Bulk Metallic Glasses

Materials Science Forum ◽

10.4028/www.scientific.net/msf.638-642.1671 ◽

2010 ◽

Vol 638-642 ◽

pp. 1671-1676

Author(s):

Hao Wang

Keyword(s):

Metallic Glasses ◽

Crystalline Phase ◽

Amorphous Materials ◽

Bulk Metallic Glasses ◽

Processing Condition ◽

Past Research ◽

Glass Forming Ability ◽

Casting Temperature ◽

Glass Forming ◽

Controlling Parameter

In the past research on bulk metallic glasses (BMGs) has been concentrated on searching for alloy composition to obtain high glass forming ability. Very few studies are on the effect of processing condition on glass forming ability of BMGs. In this study, we have prepared CuZr-based BMGs at different casting temperatures. Increasing casting temperature increases glass forming ability and decreases the amount of the crystalline phase during BMG solidification. At a high casting temperature 1723 K, fully amorphous sample is obtained at a size of 2 mm in diameter. While under the lower casting temperatures (1523 K and 1323 K), crystalline CuZr phases exist. The formation of the crystalline phase is attributed to the initial crystals or cluster survived in the BMG melt during ingot remelting. The study indicates that casting temperature can be used as the controlling parameter to produce purely amorphous materials or crystalline CuZr-phase reinforced BMG composites, and the mechanical properties and thermal stability of the BMG composites can be tailored by the amount of the crystalline phase existed in the materials.

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Glass-forming region and high refractive index of TiO2 -based glasses prepared by containerless processing

physica status solidi (c) ◽

10.1002/pssc.201200313 ◽

2012 ◽

Vol 9 (12) ◽

pp. 2424-2427 ◽

Cited By ~ 21

Author(s):

Atsunobu Masuno ◽

Yasuhiro Watanabe ◽

Hiroyuki Inoue ◽

Yasutomo Arai ◽

Jianding Yu ◽

...

Keyword(s):

Refractive Index ◽

High Refractive Index ◽

Containerless Processing ◽

Glass Forming

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Preparation of Al72Ni8Ti8Zr6Nb3Y3 Amorphous Powder and Bulk Material

Materials Science Forum ◽

10.4028/www.scientific.net/msf.879.690 ◽

2016 ◽

Vol 879 ◽

pp. 690-696

Author(s):

Yu Wu ◽

Xin Fu Wang ◽

Fu Sheng Han

Keyword(s):

Amorphous Materials ◽

Bulk Material ◽

Amorphous Powder ◽

Supercooled Liquid ◽

Bulk Sample ◽

Supercooled Liquid Region ◽

Glass Forming Ability ◽

Liquid Region ◽

Bulk Materials ◽

Glass Forming

Al-based amorphous materials are believed to be a promising light weight and high strength material, but the application has not yet been realized due to difficulties in fabricating bulk materials resulted from their quite weak glass forming ability. In order to overcome this difficulty, a solid state route was studied to fabricate bulk Al-based metallic glass. An amorphous Al72Ni8Ti8Zr6Nb3Y3 powder was first fabricated by mechanical alloying, and then the microstructure, glass-forming ability and crystallization behavior were characterized. The powder shows a wide supercooled liquid region (81K), and high activation energy for crystallization (312.6kJ/mol). By this powder, a bulk material was fabricated through high pressure (2GPa) sintering (673K and 723K). The microhardness of bulk sample is as high as 1215Hv, providing a solid basis for fabricating bulk materials and applications.

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Numerical Model of Thermal Field Developed in Fe67Cr4Mo4Ga4P12B5C4 Bulk Amorphous Alloy Processing

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.254.249 ◽

2016 ◽

Vol 254 ◽

pp. 249-254

Author(s):

Bogdan Radu ◽

Dragoş Buzdugan ◽

Cosmin Codrean ◽

Viorel Aurel Şerban ◽

George Vișan

Keyword(s):

Amorphous Alloy ◽

Amorphous Alloys ◽

Amorphous Materials ◽

Thermal Field ◽

Good Control ◽

Experimental Tests ◽

Glass Forming Ability ◽

Bulk Amorphous Alloy ◽

Bulk Amorphous Alloys ◽

Glass Forming

Metallic amorphous materials were developed during 80’s as new materials, with very interesting industrial properties (heat conductivity, magnetic properties, fusion temperature, corrosion resistance, etc.). Technology to obtain these materials, based on very rapid cooling of a melted alloy with glass forming ability, has limitations for the dimensions of the products that can be obtained with amorphous structure (thickness has to be very thin), which can be overpassed by development of bulk amorphous alloys with high glass forming ability and good control of the cooling speed. Numerical modeling of thermal field during ultra-high cooling, developed in researches presented in this paper, allows researchers to estimate the results of applying in reality certain cooling conditions. This model will help developers of bulk amorphous alloys in checking if are ensured conditions to obtain an amorphous alloy with fewer experimental tests, less time and low expenses.

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A New Mounting Medium of High Refractive Index

Scientific American ◽

10.1038/scientificamerican02131886-8429csupp ◽

1886 ◽

Vol 21 (528supp) ◽

pp. 8429-8430

Keyword(s):

Refractive Index ◽

High Refractive Index

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Accelerated Discovery of High-Refractive-Index Polyimides via First-Principles Molecular Modeling, Virtual High-Throughput Screening, and Data Mining

10.26434/chemrxiv.7670903.v1 ◽

2019 ◽

Author(s):

Mohammad Atif Faiz Afzal ◽

Mojtaba Haghighatlari ◽

Sai Prasad Ganesh ◽

Chong Cheng ◽

Johannes Hachmann

Keyword(s):

Data Mining ◽

Refractive Index ◽

High Throughput ◽

First Principles ◽

High Throughput Screening ◽

Large Scale ◽

Computational Study ◽

High Refractive Index ◽

Structural Features ◽

Learning Program

<div>We present a high-throughput computational study to identify novel polyimides (PIs) with exceptional refractive index (RI) values for use as optic or optoelectronic materials. Our study utilizes an RI prediction protocol based on a combination of first-principles and data modeling developed in previous work, which we employ on a large-scale PI candidate library generated with the ChemLG code. We deploy the virtual screening software ChemHTPS to automate the assessment of this extensive pool of PI structures in order to determine the performance potential of each candidate. This rapid and efficient approach yields a number of highly promising leads compounds. Using the data mining and machine learning program package ChemML, we analyze the top candidates with respect to prevalent structural features and feature combinations that distinguish them from less promising ones. In particular, we explore the utility of various strategies that introduce highly polarizable moieties into the PI backbone to increase its RI yield. The derived insights provide a foundation for rational and targeted design that goes beyond traditional trial-and-error searches.</div>

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