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[en] Glass forming ability (GFA) is one of the key factors hindering the application of bulk metallic glasses (BMGs). Microalloying has shown beneficial effects on GFA. However, the mechanism is still unclear. A new guidance via clusters was applied to understand and quickly choose beneficial microalloying elements for enhancing GFA which might help build a foundation for further quantitative analysis of minor alloying via clusters. Under the guidance, a series of beneficial microalloying elements could be quickly discovered, verified and understood. The results show that the beneficial microalloying elements for enhancing GFA should be chosen under the condition of bringing in new types of topologically efficiently packed clusters. (paper)
[en] Cold-rolled Zr55Cu30Ni5Al10 bulk metallic glasses (BMGs) exhibited volume dilatation across the entire range of thickness reduction fractions from 5.7% to 63%. The dilatation was dominantly attributed to the free volume generated during cold-rolling, together with any open volumes, like the voids or microcracks, or both, which survived even after sufficiently annealing the rolled sample at the temperature in the supercooled liquid region. The relaxation of free volume formed during cold-rolling resulted in more heat evolution per unit volume than that of as-cast glass. The structural change during cold-rolling could be ascribed to the increased fluctuation of atomic-level hydrostatic stress, 〈p2〉, in the glass
[en] As part of their research into the basic optical properties of laser glasses, the authors measured the two-photon absorption (2PA) coefficient β of some highly transparent oxide glasses. The authors tested several alkali silicate compositions (LG-650, LG-660, LG-670, and LSG-91H), several borosilicates (BK-3, BK-7, and BK-10), and one phosphate (LG-750)
[en] Two main by-products or waste from the production of glass fibre are following: sewage sludge containing montmorillonite clay as sorbent material and ca 50 % of organic matter as well as waste glass from aluminium borosilicate glass fibre with relatively high softening temperature (> 600 degree centigrade). In order to elaborate different new ceramic products (porous or dense composites) the mentioned by-products and illicit clay from two different layers of Apriki deposit (Latvia) with illite content in clay fraction up to 80-90 % was used as a matrix. The raw materials were investigated by differential-thermal (DTA) and XRD analysis. Ternary compositions were prepared from mixtures of 15 - 35 wt % of sludge, 20 wt % of waste glass and 45 - 65 wt % of clay and the pressed green bodies were thermally treated in sintering temperature range from 1080 to 1120 degree centigrade in different treatment conditions. Materials produced in temperature range 1090 - 1100 degree centigrade with the most optimal properties - porosity 38 - 52 %, water absorption 39 - 47 % and bulk density 1.35 - 1.67 g/cm3 were selected for production of porous ceramics and materials showing porosity 0.35 - 1.1 %, water absorption 0.7 - 2.6 % and bulk density 2.1 - 2.3 g/cm3 - for dense ceramic composites. Obtained results indicated that incorporation up to 25 wt % of sewage sludge is beneficial for production of both ceramic products and glass-ceramic composites according to the technological properties. Structural analysis of elaborated composite materials was performed by scanning electron microscopy(SEM). By X-ray diffraction analysis (XRD) the quartz, diopside and anorthite crystalline phases were detected. (Author) 16 refs.
[en] In the present work, a mass spectrometric Knudsen effusion method has been used to study the chemical forms of vapors with Na, B and Te over a borosilicate glass with simple composition 1Na2O-1B2O3-3SiO2-0.15TeO2. (orig./RK)
[en] In the present article we discuss a new class of scintillation materials that are prospective for application in high energy physics experiments and for detection of neutrons in a wide energy range.(authors)
[en] Based on the cluster line criterion, the Ag addition into the Cu8Zr5 cluster composition is investigated for the search of ternary Cu-Zr-Ag bulk metallic glasses with high glass forming abilities. Two initial binary compositions Cu0.618Zr0.382 and Cu0.64Zr0.36 are selected. The former one corresponds to a deep eutectic point; it is also the composition of the Cu8Zr5 icosahedron, which is derived from the Cu8Zr3 structure. The latter one, which can be regarded as the Cu8Zr5 cluster plus a glue atom Cu, is the best glass-forming composition in the Cu-Zr binary system. Two composition lines (Cu0.618Zr0.382)1-xAg x and (Cu0.64Zr0.36)1-xAg x are thus constructed in the Cu-Zr-Ag system by linking these two compositions with the third constitute Ag. A series of Cu-Zr-Ag bulk metallic glasses are found with 2-8 at.% Ag contents in both composition lines. The optimum composition (Cu0.618Zr0.382)0.92Ag0.08 within the searched region with the highest T g/T l = 0.633, is located along the cluster line (Cu0.618Zr0.382)1-xAg x, where the deep eutectic Cu0.618Zr0.382 exactly corresponds to the dense packing cluster Cu8Zr5. The alloying mechanism is discussed in the light of atomic size and electron concentration factors
[en] A solution now studied for the storage of fission products issued from the reprocessing plants consists in their introduction in a vitreous matrix. The dissipation of energy caused by the radioactive decay of fission products produces a partial devitrification of glasses by a temperature increase. The crystalline formed phases are observed by scanning electron microscopy and chemically analysed by X-ray emission. The identification of crystalline phases is realized by the comparison of the data given by X-ray diffraction and the previous results. Then the volumic fraction of different phases is evaluated. The study is presented for the aluminosilicate and borosilicate glasses
[fr]Une des solutions actuellement etudiees pour stocker les produits de fission issus des usines de retraitement consiste a les inclure dans une matrice vitreuse. L'energie degagee par la decroissance radioactive des produits de fission entraine une elevation de temperature des blocs de verre qui peuvent ainsi subir une devitrification partielle. Les phases cristallines formees sont visualisees par microscopie electronique a balayage et analysees chimiquement par emission X. La comparaison de ces resultats avec les donnees fournies par la diffraction des rayons X permet d'identifier les phases cristallisees. La mesure de la fraction volumique des differentes phases est alors realisee. L'etude est faite pour deux types de verre: le silico-alumineux et le silico-borate
[en] Highlights: • A novel method was proposed to estimate the volume of shear transformation zone (STZ) in bulk metallic glass through statistical analysis of the serration behavior in nanoindentation. • It was found that the STZ size exhibits an increasing trend during nanoindentation. • The STZ activation can promote the formation of self-organized critical (SOC) phenomena during serrated flow. - Abstract: This paper presents the research on the evolution of shear transformation zone (STZ) in a Pd-based bulk metallic glass (BMG) during serrated flow under nanoindentation. A novel method of estimating the STZ volume through statistical analysis of the serrated flow behavior was proposed for the first time. Based on the proposed method, the STZ volume of the studied BMG at various peak loads have been systematically investigated. The results indicate that the measured STZ volumes are in good agreement with that documented in literature, and the STZ size exhibits an increasing trend during indentation. Moreover, the correlation between the serrated flow dynamics and the STZ activation has also been evaluated. It is found that the STZ activation can promote the formation of self-organized critical (SOC) state during serrated flow.