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Tournier RF, Ojovan MI. NiTi 2, a New Liquid Glass. MATERIALS (BASEL, SWITZERLAND) 2023; 16:6681. [PMID: 37895662 PMCID: PMC10608734 DOI: 10.3390/ma16206681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 09/25/2023] [Accepted: 10/11/2023] [Indexed: 10/29/2023]
Abstract
Many endothermic liquid-liquid transitions, occurring at a temperature Tn+ above the melting temperature Tm, are related to previous exothermic transitions, occurring at a temperature Tx after glass formation below Tg, with or without attached crystallization and predicted by the nonclassical homogenous nucleation equation. A new thermodynamic phase composed of broken bonds (configurons), driven by percolation thresholds, varying from ~0.145 to Δε, is formed at Tx, with a constant enthalpy up to Tn+. The liquid fraction Δε is a liquid glass up to Tn+. The solid phase contains glass and crystals. Molecular dynamics simulations are used to induce, in NiTi2, a reversible first-order transition by varying the temperature between 300 and 1000 K under a pressure of 1000 GPa. Cooling to 300 K, without applied pressure, shows the liquid glass presence with Δε = 0.22335 as memory effect and Tn+ = 2120 K for Tm = 1257 K.
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Affiliation(s)
- Robert F. Tournier
- UPR 3228 Centre National de la Recherche Scientifique, Laboratoire National des Champs Magnétiques Intenses, European Magnetic Field Laboratory, Institut National des Sciences Appliquées de Toulouse, Université Grenoble Alpes, F-31400 Toulouse, France;
| | - Michael I. Ojovan
- Department of Materials, Imperial College London, London SW7 2AZ, UK
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Bruns S, Minnert C, Pethö L, Michler J, Durst K. Room Temperature Viscous Flow of Amorphous Silica Induced by Electron Beam Irradiation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2205237. [PMID: 36638235 PMCID: PMC9982523 DOI: 10.1002/advs.202205237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 12/01/2022] [Indexed: 06/17/2023]
Abstract
The increasing use of oxide glasses in high-tech applications illustrates the demand of novel engineering techniques on nano- and microscale. Due to the high viscosity of oxide glasses at room temperature, shaping operations are usually performed at temperatures close or beyond the point of glass transition Tg . Those treatments, however, are global and affect the whole component. It is known from the literature that electron irradiation facilitates the viscous flow of amorphous silica near room temperature for nanoscale components. At the micrometer scale, however, a comprehensive study on this topic is still pending. In the present study, electron irradiation inducing viscous flow at room temperature is observed using a micropillar compression approach and amorphous silica as a model system. A comparison to high temperature yielding up to a temperature of 1100 °C demonstrates that even moderate electron irradiation resembles the mechanical response of 600 °C and beyond. As an extreme case, a yield strength as low as 300 MPa is observed with a viscosity indicating that Tg has been passed. Those results show that electron irradiation-facilitated viscous flow is not limited to the nanoscale which offers great potential for local microengineering.
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Affiliation(s)
- Sebastian Bruns
- Department of Materials ScienceTechnical University of DarmstadtAlarich‐Weiss‐Straße 2DE‐64287DarmstadtGermany
| | - Christian Minnert
- Department of Materials ScienceTechnical University of DarmstadtAlarich‐Weiss‐Straße 2DE‐64287DarmstadtGermany
| | - Laszlo Pethö
- EmpaSwiss Federal Laboratories for Materials Science and TechnologyFeuerwerkerstrasse 39ThunCH‐3602Switzerland
| | - Johann Michler
- EmpaSwiss Federal Laboratories for Materials Science and TechnologyFeuerwerkerstrasse 39ThunCH‐3602Switzerland
| | - Karsten Durst
- Department of Materials ScienceTechnical University of DarmstadtAlarich‐Weiss‐Straße 2DE‐64287DarmstadtGermany
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Galimzyanov BN, Doronina MA, Mokshin AV. Arrhenius Crossover Temperature of Glass-Forming Liquids Predicted by an Artificial Neural Network. MATERIALS (BASEL, SWITZERLAND) 2023; 16:1127. [PMID: 36770134 PMCID: PMC9921151 DOI: 10.3390/ma16031127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/18/2023] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
The Arrhenius crossover temperature, TA, corresponds to a thermodynamic state wherein the atomistic dynamics of a liquid becomes heterogeneous and cooperative; and the activation barrier of diffusion dynamics becomes temperature-dependent at temperatures below TA. The theoretical estimation of this temperature is difficult for some types of materials, especially silicates and borates. In these materials, self-diffusion as a function of the temperature T is reproduced by the Arrhenius law, where the activation barrier practically independent on the temperature T. The purpose of the present work was to establish the relationship between the Arrhenius crossover temperature TA and the physical properties of liquids directly related to their glass-forming ability. Using a machine learning model, the crossover temperature TA was calculated for silicates, borates, organic compounds and metal melts of various compositions. The empirical values of the glass transition temperature Tg, the melting temperature Tm, the ratio of these temperatures Tg/Tm and the fragility index m were applied as input parameters. It has been established that the temperatures Tg and Tm are significant parameters, whereas their ratio Tg/Tm and the fragility index m do not correlate much with the temperature TA. An important result of the present work is the analytical equation relating the temperatures Tg, Tm and TA, and that, from the algebraic point of view, is the equation for a second-order curved surface. It was shown that this equation allows one to correctly estimate the temperature TA for a large class of materials, regardless of their compositions and glass-forming abilities.
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Affiliation(s)
- Bulat N. Galimzyanov
- Institute of Physics, Kazan Federal University, 420008 Kazan, Russia
- Udmurt Federal Research Center of the Ural Branch of RAS, 426067 Izhevsk, Russia
| | - Maria A. Doronina
- Institute of Physics, Kazan Federal University, 420008 Kazan, Russia
| | - Anatolii V. Mokshin
- Institute of Physics, Kazan Federal University, 420008 Kazan, Russia
- Udmurt Federal Research Center of the Ural Branch of RAS, 426067 Izhevsk, Russia
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Multiple Melting Temperatures in Glass-Forming Melts. SUSTAINABILITY 2022. [DOI: 10.3390/su14042351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
All materials are vitrified by fast quenching even monoatomic substances. Second melting temperatures accompanied by weak exothermic or endothermic heat are often observed at Tn+ after remelting them above the equilibrium thermodynamic melting transition at Tm. These temperatures, Tn+, are due to the breaking of bonds (configurons formation) or antibonds depending on the thermal history, which is explained by using a nonclassical nucleation equation. Their multiple existence in monoatomic elements is now demonstrated by molecular dynamics simulations and still predicted. Proposed equations show that crystallization enthalpy is reduced at the temperature Tx due to new vitrification of noncrystallized parts and their melting at Tn+. These glassy parts, being equal above Tx to singular values or to their sum, are melted at various temperatures Tn+ and attain 100% in Cu46Zr46Al8 and 86.7% in bismuth. These first order transitions at Tn+ are either reversible or irreversible, depending on the formation of super atoms, either solid or liquid.
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He Y, Wu Y, Bu F, Zhang Y, Zhang Y, Hei B, Zhang J, Wang H. Re-Examination of the Microstructural Evolution in Undercooled Co-18.5at.%B Eutectic Alloy. MATERIALS 2022; 15:ma15041315. [PMID: 35207849 PMCID: PMC8874835 DOI: 10.3390/ma15041315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/01/2022] [Accepted: 02/04/2022] [Indexed: 12/10/2022]
Abstract
The undercooling (∆T) dependencies of the solidification pathways, microstructural evolution, and recalescence behaviors of undercooled Co-18.5at.%B eutectic alloys were systematically explored. Up to four possible solidification pathways were identified: (1) A lamellar eutectic structure consisting of the FCC–Co and Co3B phase forms, with extremely low ΔT; (2) The FCC–Co phase primarily forms, followed by the eutectic growth of the FCC–Co and Co2B phases when ΔT < 100 K; (3) As the ΔT increases further, the FCC–Co phase primarily forms, followed by the metastable Co23B6 phase with the trace of an FCC–Co and Co23B6 eutectic; (4) When the ΔT increases to 277 K, the FCC–Co phase primarily forms, followed by an FCC–Co and Co3B eutectic, which is similar in composition to the microstructure formed with low ΔT. The mechanisms of the microstructural evolution and the phase selection are interpreted on the basis of the composition segregation, the skewed coupled zone, the strain-induced transformation, and the solute trapping. Moreover, the prenucleation of the primary FCC–Co phase was also detected from an analysis of the different recalescence behaviors. The present work not only enriches our knowledge about the phase selection behavior in the undercooled Co–B system, but also provides us with guidance for controlling the microstructures and properties practically.
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Affiliation(s)
- Yixuan He
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China; (Y.W.); (F.B.); (Y.Z.); (Y.Z.); (B.H.); (J.Z.)
- Center of Advanced Lubrication and Seal Materials, Northwestern Polytechnical University, Xi’an 710072, China
- Collaborative Innovation Center of NPU, Shanghai 201108, China
- Correspondence: (Y.H.); (H.W.); Tel.: +86-29-8846-0294 (Y.H.)
| | - Yuhao Wu
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China; (Y.W.); (F.B.); (Y.Z.); (Y.Z.); (B.H.); (J.Z.)
- Center of Advanced Lubrication and Seal Materials, Northwestern Polytechnical University, Xi’an 710072, China
| | - Fan Bu
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China; (Y.W.); (F.B.); (Y.Z.); (Y.Z.); (B.H.); (J.Z.)
- Center of Advanced Lubrication and Seal Materials, Northwestern Polytechnical University, Xi’an 710072, China
| | - Yiyuan Zhang
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China; (Y.W.); (F.B.); (Y.Z.); (Y.Z.); (B.H.); (J.Z.)
- Center of Advanced Lubrication and Seal Materials, Northwestern Polytechnical University, Xi’an 710072, China
| | - Yifan Zhang
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China; (Y.W.); (F.B.); (Y.Z.); (Y.Z.); (B.H.); (J.Z.)
| | - Bo Hei
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China; (Y.W.); (F.B.); (Y.Z.); (Y.Z.); (B.H.); (J.Z.)
| | - Jianbao Zhang
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China; (Y.W.); (F.B.); (Y.Z.); (Y.Z.); (B.H.); (J.Z.)
- Center of Advanced Lubrication and Seal Materials, Northwestern Polytechnical University, Xi’an 710072, China
| | - Haifeng Wang
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China; (Y.W.); (F.B.); (Y.Z.); (Y.Z.); (B.H.); (J.Z.)
- Center of Advanced Lubrication and Seal Materials, Northwestern Polytechnical University, Xi’an 710072, China
- Correspondence: (Y.H.); (H.W.); Tel.: +86-29-8846-0294 (Y.H.)
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Tournier RF, Ojovan MI. Prediction of Second Melting Temperatures Already Observed in Pure Elements by Molecular Dynamics Simulations. MATERIALS 2021; 14:ma14216509. [PMID: 34772033 PMCID: PMC8585396 DOI: 10.3390/ma14216509] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/19/2021] [Accepted: 10/26/2021] [Indexed: 12/01/2022]
Abstract
A second melting temperature occurs at a temperature Tn+ higher than Tm in glass-forming melts after heating them from their glassy state. The melting entropy is reduced or increased depending on the thermal history and on the presence of antibonds or bonds up to Tn+. Recent MD simulations show full melting at Tn+ = 1.119Tm for Zr, 1.126Tm for Ag, 1.219Tm for Fe and 1.354Tm for Cu. The non-classical homogeneous nucleation model applied to liquid elements is based on the increase of the Lindemann coefficient with the heating rate. The glass transition at Tg and the nucleation temperatures TnG of glacial phases are successfully predicted below and above Tm. The glass transition temperature Tg increases with the heating rate up to Tn+. Melting and crystallization of glacial phases occur with entropy and enthalpy reductions. A universal law relating Tn+ and TnG around Tm shows that TnG cannot be higher than 1.293Tm for Tn+= 1.47Tm. The enthalpies and entropies of glacial phases have singular values, corresponding to the increase of percolation thresholds with Tg and TnG above the Scher and Zallen invariant at various heating and cooling rates. The G-phases are metastable up to Tn+ because the antibonds are broken by homogeneous nucleation of bonds.
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Affiliation(s)
- Robert F. Tournier
- UPR 3228 Centre National de la Recherche Scientifique, Laboratoire National des Champs Magnétiques Intenses, European Magnetic Field Laboratory, Institut National des Sciences Appliquées de Toulouse, Université Grenoble Alpes, F-31400 Toulouse, France
- Correspondence:
| | - Michael I. Ojovan
- Department of Materials, Imperial College London, London SW7 2AZ, UK;
- Department of Radiochemistry, Moscow State University, 119991 Moscow, Russia
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Ojovan MI, Tournier RF. On Structural Rearrangements Near the Glass Transition Temperature in Amorphous Silica. MATERIALS 2021; 14:ma14185235. [PMID: 34576458 PMCID: PMC8466242 DOI: 10.3390/ma14185235] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/04/2021] [Accepted: 09/08/2021] [Indexed: 12/29/2022]
Abstract
The formation of clusters was analyzed in a topologically disordered network of bonds of amorphous silica (SiO2) based on the Angell model of broken bonds termed configurons. It was shown that a fractal-dimensional configuron phase was formed in the amorphous silica above the glass transition temperature Tg. The glass transition was described in terms of the concepts of configuron percolation theory (CPT) using the Kantor-Webman theorem, which states that the rigidity threshold of an elastic percolating network is identical to the percolation threshold. The account of configuron phase formation above Tg showed that (i) the glass transition was similar in nature to the second-order phase transformations within the Ehrenfest classification and that (ii) although being reversible, it occurred differently when heating through the glass–liquid transition to that when cooling down in the liquid phase via vitrification. In contrast to typical second-order transformations, such as the formation of ferromagnetic or superconducting phases when the more ordered phase is located below the transition threshold, the configuron phase was located above it.
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Affiliation(s)
- Michael I. Ojovan
- Department of Materials, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK
- Department of Radiochemistry, Moscow State University Named after M.V. Lomonosov, Leninskie Gory 1, Bd.3, 119991 Moscow, Russia
- Correspondence: ; Tel.: +44-747-828-9098
| | - Robert F. Tournier
- Laboratoire National des Champs Magnétiques Intenses, European Magnetic Field Laboratory, UPR 3228 Centre National de la Recherche Scientifique, Université Grenoble Alpes, Institut National des Sciences Appliquées de Toulouse, F-31400 Toulouse, France;
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