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Akihisa Inoue - One of the best experts on this subject based on the ideXlab platform.
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Crystallization behavior of Fe- and Co-based bulk metallic glasses and their Glass-Forming Ability
Materials Chemistry and Physics, 2015Co-Authors: Dmitry Louzguine-luzgin, A. I. Bazlov, Sergey V. Ketov, Akihisa InoueAbstract:Abstract In the present work we study and compare the crystallization behavior of Fe- and Co-based good bulk glass formers with an exceptionally high Glass-Forming Ability leading to the critical thickness of cast samples reaching 1 cm. For Fe-based alloys we also investigate the effect of opposite C/B content ratio on the Glass-Forming Ability and the crystallization behavior. The structure and phase composition of the glassy samples were examined by conventional X-ray diffractometry and transmission electron microscopy while thermal stAbility and phase transformations were studied by differential scanning calorimetry. The reasons for high Glass-Forming Ability are discussed. The Glass-Forming Ability of the studied alloys depends on both factors: the type of crystallization reaction and characteristic temperatures.
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Glass-Forming Ability of Bulk Pd40Ni10Cu30P20 Alloy
Materials Transactions JIM, 2014Co-Authors: Nobuyuki Nishiyama, Akihisa InoueAbstract:The partial replacement of Ni by 30 at%Cu for the Pd40Ni40-xCuxP20 alloys was found to cause the drastic increase in the Glass-Forming Ability as is evidenced from the decrease in the critical cooling rate for glass formation (R(c)) to 1.5 K/s and the increase in the critical sample thickness for glass formation (t(max)) to 40 mm. The Pd40Ni10Cu30P20 amorphous alloy exhibits the distinct glass transition, followed by the appearance of a wide supercooled liquid region (Delta T-x(= T-x-T-g)) reaching 95 K and then a single-stage crystallization. The differential thermal analysis indicates that the Pd-Ni-Cu-P alloy has a single stage melting reaction at 804 K. The resulting T-g/T-m is measured to be as high as 0.72. Considering that the R(c), t(max), Delta T-x and T-g/T-m are 128 K/s, about 7 mm, 63 K and 0.66, respectively, for a Pd40Ni40P20 amorphous alloy with the largest Glass-Forming Ability in previously reported Pd-based alloys, the present new Pd-Ni-Cu-P amorphous alloy is concluded to have a much larger Glass-Forming Ability and a higher thermal stAbility of the supercooled liquid. The crystallization occurs through a single stage due to the precipitation of more than four kinds of crystalline phases and hence the necessity of long-range rearrangement of the constituent elements for the progress of the precipitation seems to cause the large Glass-Forming Ability and the high thermal stAbility of the supercooled liquid through the retardation of crystallization. The finding of the new Pd-based amorphous alloy with the much larger Glass-Forming Ability is important for the future development of basic science and engineering application of amorphous alloys.
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an assessment of binary metallic glasses correlations between structure glass forming Ability and stAbility
International Materials Reviews, 2010Co-Authors: D B Miracle, Dmitri V Louzguineluzgin, Larissa V Louzguinaluzgina, Akihisa InoueAbstract:Abstract This manuscript explores the influence of atomic structure on glass forming Ability and thermal stAbility in binary metallic glasses. A critical assessment gives literature data for 628 alloys from 175 binary glass systems. The atomic structure is quantified for each alloy using the efficient cluster packing model. Comparison of atomic structure with amorphous thickness and thermal stAbility gives the following major results. Binary glasses show a strong preference for discrete solute to solvent atomic radius ratios R*, which give efficient local atomic packing. Of 15 possible R* values, only five are common and only four represent the most stable glasses. The most stable binary glasses are also typically solute rich, with enough solute atoms to fill all the solute sites and roughly one-third of the solvent sites. This suggests that antisite defects, where solutes occupy solvent atom sites, are important in the glass forming Ability of the most stable glasses. This stabilising effect resul...
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A critical analysis of the Glass-Forming Ability of alloys
Journal of Non-crystalline Solids, 2009Co-Authors: C. Suryanarayana, Ichiro Seki, Akihisa InoueAbstract:Several empirical rules have been proposed during the past few years to synthesize bulk metallic glasses. But, the real reasons for the improved Glass-Forming Ability of these alloys are still not clear and the Ability to design alloy compositions to enable synthesis of larger diameter rods has not improved. The present work conducts a critical analysis of the existing data in terms of the different Glass-Forming criteria and concludes that the available parameters cannot satisfactorily predict the GFA and explain all the observed data. Reasons for this failure have been suggested.
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Influence of thermal conductivity on the Glass-Forming Ability of Ni-based and Cu-based alloys
Applied Physics Letters, 2006Co-Authors: Dmitri V. Louzguine-luzgin, Albertus D. Setyawan, Hidemi Kato, Akihisa InoueAbstract:In the present letter we compare the thermal conductivities of Cu- and Ni-based alloys in relation with their cooling rates and Glass-Forming abilities. The cooling rates obtained for Cu- and Ni-based bulk Glass-Forming alloys are found to scale with the thermal conductivities of the base elements. Relatively low thermal conductivity of Ni-based alloy compared to the Cu-based one explains its lower Glass-Forming Ability. The results also indicate that the thermal conductivity of the molten alloy should be also used as an indicator of the Glass-Forming Ability among the other factors.
Christel A. S. Bergström - One of the best experts on this subject based on the ideXlab platform.
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Early drug development predictions of Glass-Forming Ability and physical stAbility of drugs.
European Journal of Pharmaceutical Sciences, 2013Co-Authors: Denny Mahlin, Christel A. S. BergströmAbstract:Abstract The purpose of this study was to investigate if rapidly measured physical properties can predict Glass-Forming Ability and glass stAbility of drug compounds. A series of 50 structurally diverse drug molecules were studied with respect to Glass-Forming Ability and, for glass-formers ( n = 24), the physical stAbility upon 1 month of storage was determined. Spray-drying and melt-cooling were used to produce the amorphous material and the solid state was analysed by Differential Scanning Calorimetry (DSC) and Powder X-ray Diffraction. Thermal properties and molecular weight (Mw) were used to develop predictive models of (i) Glass-Forming Ability and (ii) physical stAbility. In total, the Glass-Forming Ability was correctly predicted for 90% of the drugs from their Mw alone. As a rule of thumb, drugs with Mw greater than 300 g/mole are expected to be transformed to its amorphous state by using standard process technology. Glass transition temperature and Mw predicted the physical stAbility upon storage correctly for 78% of the Glass-Forming compounds. A strong sigmoidal relationship ( R 2 of 0.96) was identified between crystallization temperature and stAbility. These findings have the potential to rationalize decisions schemes for utilizing and developing amorphous formulations, through early predictions of Glass-Forming Ability from Mw and physical stAbility from simple DSC characterization.
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toward in silico prediction of glass forming Ability from molecular structure alone a screening tool in early drug development
Molecular Pharmaceutics, 2011Co-Authors: Denny Mahlin, Sopana Ponnambalam, Mina Heidarian Hockerfelt, Christel A. S. BergströmAbstract:We present a novel computational tool which predicts the Glass-Forming Ability of drug compounds solely from their molecular structure. Compounds which show solid-state limited aqueous solubility were selected, and their Glass-Forming Ability was determined upon spray-drying, melt-quenching and mechanical activation. The solids produced were analyzed by differential scanning calorimetry (DSC) and powder X-ray diffraction. Compounds becoming at least partially amorphous on processing were classified as glass-formers, whereas those remaining crystalline regardless of the process method were classified as non-Glass-Forming compounds. A predictive model of the Glass-Forming Ability, designed to separate between these two classes, was developed through the use of partial least-squares projection to latent structure discriminant analysis (PLS-DA) and calculated molecular descriptors. In total, ten of the 16 compounds were determined experimentally to be good glass-formers and the PLS-DA model correctly sorted 1...
Xiufang Bian - One of the best experts on this subject based on the ideXlab platform.
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The glass‐forming Ability and thermal stAbility of novolac–phenolic resin
Polymer Composites, 2011Co-Authors: Xiufang Bian, Lei YangAbstract:Glass-Forming Ability and thermal stAbility of novolac–phenolic resin with different contents of curing agent hexamethylenetramine (HMTA) are investigated. Melt fragility (Mg) and Tgd (Tgd = Tg/Td) are proposed to characterize Glass-Forming Ability and thermal stAbility of the novolac–phenolic resin, respectively. It is found that Mg has a negative linear relationship with Tgd. The lower Mg represents the better Glass-Forming Ability of liquid phenolic resin while the higher Tgd represents the better thermal stAbility of the fully cured phenolic resin. Further more, Mg establishes a kinetic relationship between Glass-Forming Ability of liquid uncured and thermal stAbility of fully cured novolac–phenolic resin in terms of comparing with Tgd. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers
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Prediction of Glass-Forming Ability of metallic liquids
Applied Physics Letters, 2007Co-Authors: Xiufang Bian, Xiaoqian Lv, Caidong WangAbstract:We propose a concept for the prediction of the Glass-Forming Ability (GFA) before quenching through studies of the stabilization of clusters in metallic liquids in terms of a parameter, B=dr∕dT (r is the correlation radius of clusters and T is the absolute temperature). Strong correlation between B and GFA was found for a broad range of alloy systems. When the absolute value of B is lower than 1×10−4nm∕K, the metallic liquid can be prepared into a metallic glass. This criterion is important for studies of Glass-Forming abilities of metallic liquids in the future.
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Liquid structure : Is it directly correlative to Glass-Forming Ability?
Physics Letters A, 2007Co-Authors: Yan Zhao, Xiufang BianAbstract:Abstract A new concept, the structural fragility of liquids, has been proposed based on different structural changing behaviors with temperature. A fragility parameter, F s , was introduced to quantify the structural fragility, and the Glass-Forming Ability (GFA) of some binary alloys was discussed subsequently. The results show that the structural fragility is closely related to the GFA of liquids, a smaller F s corresponds to a higher GFA.
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Effect of Ni on Glass-Forming Ability of Cu-Ti-based amorphous alloys
Transactions of Nonferrous Metals Society of China, 2006Co-Authors: Jiang Jiang, Xiufang Bian, Ying DongAbstract:Abstract Ribbons of amorphous Cu-Ti-Ni alloys were prepared by the melt spinning method. The amorphous structure of these ribbons was confirmed by X-ray diffractametry and transmission electron microscopy. The effect of Ni on the Glass-Forming Ability of Cu-Ti-based alloys was studied by differential scanning calorimetry(DSC). It is found that the supercooled liquid region, ΔTx value shows the maximum value of 61°C at x=10 in the Cu50Ti50-xNix (x=0, 5, 10, 15 mole fraction, %) system. And the reduced glass transition temperature, Trg, is smaller than 0.45. The glass forming Ability(GFA) of Cu-Ti alloy is not effectively promoted by Ni addition.
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Fragility of superheated melts and Glass-Forming Ability in Al-based alloys
Physics Letters A, 2005Co-Authors: Xiufang Bian, Lina HuAbstract:Abstract A new concept, the fragility of superheated melt defined as M = | ∂ η ( T ) / η ( T L ) ∂ T / T L | T = T L | = | ∂ η r ∂ T r | T r = 1 | , has been proposed in this work. It has been found that this kind of fragility value of liquid above liquidus temperature is closely related to the Glass-Forming Ability in Al-based amorphous alloys. By calculation of the M, the Glass-Forming Ability of Al-based amorphous alloys could be predicted prior to the preparation for amorphous solids.
Xuebin Yu - One of the best experts on this subject based on the ideXlab platform.
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a new ti zr hf cu ni si sn bulk amorphous alloy with high glass forming Ability
Journal of Alloys and Compounds, 2007Co-Authors: Yongjiang Huang, J Shen, Xuebin YuAbstract:The effect of Sn substitution for Cu on the Glass-Forming Ability was investigated in Ti41.5Zr2.5Hf5Cu42.5−xNi7.5Si1Snx (x = 0, 1, 3, 5, 7) alloys by using differential scanning calorimetry (DSC) and X-ray diffractometry. The alloy containing 5% Sn shows the highest Glass-Forming Ability (GFA) among the Ti–Zr–Hf–Cu–Ni–Si–Sn system. Fully amorphous rod sample with diameters up to 6 mm could be successfully fabricated by the copper mold casting Ti41.5Zr2.5Hf5Cu37.5Ni7.5Si1Sn5 alloy. The activation energies for glass transition and crystallization for Ti41.5Zr2.5Hf5Cu37.5Ni7.5Si1Sn5 amorphous alloy are both larger than those values for the Sn-free alloy. The enhancement in GFA and thermal stAbility after the partial replacement of Cu by Sn may be contributed to the strong atomic bonding nature between Ti and Sn and the increasing of atomic packing density. The amorphous Ti41.5Zr2.5Hf5Cu37.5Ni7.5Si1Sn5 alloy also possesses superior mechanical properties.
Denny Mahlin - One of the best experts on this subject based on the ideXlab platform.
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Early drug development predictions of Glass-Forming Ability and physical stAbility of drugs.
European Journal of Pharmaceutical Sciences, 2013Co-Authors: Denny Mahlin, Christel A. S. BergströmAbstract:Abstract The purpose of this study was to investigate if rapidly measured physical properties can predict Glass-Forming Ability and glass stAbility of drug compounds. A series of 50 structurally diverse drug molecules were studied with respect to Glass-Forming Ability and, for glass-formers ( n = 24), the physical stAbility upon 1 month of storage was determined. Spray-drying and melt-cooling were used to produce the amorphous material and the solid state was analysed by Differential Scanning Calorimetry (DSC) and Powder X-ray Diffraction. Thermal properties and molecular weight (Mw) were used to develop predictive models of (i) Glass-Forming Ability and (ii) physical stAbility. In total, the Glass-Forming Ability was correctly predicted for 90% of the drugs from their Mw alone. As a rule of thumb, drugs with Mw greater than 300 g/mole are expected to be transformed to its amorphous state by using standard process technology. Glass transition temperature and Mw predicted the physical stAbility upon storage correctly for 78% of the Glass-Forming compounds. A strong sigmoidal relationship ( R 2 of 0.96) was identified between crystallization temperature and stAbility. These findings have the potential to rationalize decisions schemes for utilizing and developing amorphous formulations, through early predictions of Glass-Forming Ability from Mw and physical stAbility from simple DSC characterization.
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toward in silico prediction of glass forming Ability from molecular structure alone a screening tool in early drug development
Molecular Pharmaceutics, 2011Co-Authors: Denny Mahlin, Sopana Ponnambalam, Mina Heidarian Hockerfelt, Christel A. S. BergströmAbstract:We present a novel computational tool which predicts the Glass-Forming Ability of drug compounds solely from their molecular structure. Compounds which show solid-state limited aqueous solubility were selected, and their Glass-Forming Ability was determined upon spray-drying, melt-quenching and mechanical activation. The solids produced were analyzed by differential scanning calorimetry (DSC) and powder X-ray diffraction. Compounds becoming at least partially amorphous on processing were classified as glass-formers, whereas those remaining crystalline regardless of the process method were classified as non-Glass-Forming compounds. A predictive model of the Glass-Forming Ability, designed to separate between these two classes, was developed through the use of partial least-squares projection to latent structure discriminant analysis (PLS-DA) and calculated molecular descriptors. In total, ten of the 16 compounds were determined experimentally to be good glass-formers and the PLS-DA model correctly sorted 1...