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W. Gust - One of the best experts on this subject based on the ideXlab platform.

  • A new mode of the discontinuous Dissolution Reaction in Mg-10 wt.% Al alloy
    Materials Chemistry and Physics, 2001
    Co-Authors: D. Bradai, Paweł Zięba, E. Bischoff, W. Gust
    Abstract:

    The occurrence of discontinuous precipitation (DP) and Dissolution Reactions has been investigated in Mg-10 wt.% Al alloy. The application of a special cyclic heat treatment allowed to observe a new mode of the discontinuous Dissolution Reaction. The Reaction starts preferably and occurs faster at the original locations of the grain boundaries, which is in contrast to the commonly observed behaviour where the Reaction occurs, in the early stage, primarily at the Reaction front of the former DP colonies. The proposed explanation is attributed to a characteristic movement of the Reaction front of the DP colony away from and back to the original location of the grain boundary during subsequent cycles of ageing and Dissolution.

  • AEM of the solute redistribution during discontinuous Dissolution
    Mikrochimica Acta, 2000
    Co-Authors: Paweł Zięba, W. Gust
    Abstract:

    High spatial resolution X-ray microanalysis of thin foils in a transmission electron microscope has been used for the first time to examine the residual solute content profiles resulting from the discontinuous Dissolution Reaction in a Ni-4 at. % Sn alloy. The sharp change in the Sn content, detected performing the line scans across the Reaction front, indicated that the solute redistribution occurred just at the Reaction front. The Sn profiles measured along the Reaction front were the reverse of those typical for the discontinuous precipitation Reaction, with a relatively higher excess amount of tin stored close to the position where the Ni3Sn lamellae had previously existed. The obtained results also suggest that the chemistry and shape of profiles are not only dependent on the Dissolution temperature, but that the initial state of the single cell just before the beginning of the discontinuous Dissolution Reaction plays an important role.

  • The kinetics of the discontinuous precipitation and Dissolution in Mg-rich Al alloys
    Journal of Materials Science, 1999
    Co-Authors: D. Bradai, Paweł Zięba, M. Kadi-hanifi, W. M. Kuschke, W. Gust
    Abstract:

    The morphology and growth kinetics of the discontinuous precipitation and Dissolution Reactions in supersaturated Mg-Al solid solutions containing 7.3, 9.1 and 10.9 at % Al have been investigated by optical and scanning electron microscopy and X-ray measurements. The volume fraction of regions transformed by the discontinuous precipitation Reaction, the Reaction front velocity, the interlamellar spacing and the average composition of the solute-depleted lamellae were determined as a function of the temperature. For the first time, the kinetics of the discontinuous Dissolution Reaction has been studied in the Mg-Al system. It has been shown that the transport of the solute atoms during both Reactions is governed by grain boundary diffusion.

  • On the discontinuous Dissolution Reaction in a Mg-8 wt.% Al alloy
    Practical Metallography, 1998
    Co-Authors: D. Bradai, M. Kadi-hanifi, P. Zieba, W. Gust
    Abstract:

    The present studies of a Mg-8 wt.% Al alloy have shown that the discontinuous precipitation Reaction is occurring during ageing at 500 K. A subsequent Dissolution heat treatment at 625 K revealed that the Dissolution process occurs in the discontinuous mode by receding of the former Reaction front of the discontinuous precipitation towards the position of the original grain boundary. The solid solution resulting from the discontinuous Dissolution process is very inhomogeneous. As the theoretical calculations proved the differences in the Al content can be as large as 15 wt.%.

Danielle Hilhorst - One of the best experts on this subject based on the ideXlab platform.

  • a fast precipitation and Dissolution Reaction for a Reaction diffusion system arising in a porous medium
    Nonlinear Analysis-real World Applications, 2009
    Co-Authors: Nicolas Bouillard, Robert Eymard, Marie Henry, Raphaele Herbin, Danielle Hilhorst
    Abstract:

    Abstract This paper is devoted to the study of a fast Reaction–diffusion system arising in reactive transport. It extends the articles [R. Eymard, T. Gallouet, R. Herbin, D. Hilhorst, M. Mainguy, Instantaneous and noninstantaneous Dissolution: Approximation by the finite volume method, ESAIM Proc. (1998); J. Pousin, Infinitely fast kinetics for Dissolution and diffusion in open reactive systems, Nonlinear Anal. 39 (2000) 261–279] since a precipitation and Dissolution Reaction is considered so that the Reaction term is not sign-definite and is moreover discontinuous. Energy type methods allow us to prove uniform estimates and then to study the limiting behavior of the solution as the kinetic rate tends to infinity in the special situation of one aqueous species and one solid species.

  • A fast precipitation and Dissolution Reaction for a Reaction–diffusion system arising in a porous medium☆
    Nonlinear Analysis: Real World Applications, 2009
    Co-Authors: Nicolas Bouillard, Robert Eymard, Marie Henry, Raphaele Herbin, Danielle Hilhorst
    Abstract:

    Abstract This paper is devoted to the study of a fast Reaction–diffusion system arising in reactive transport. It extends the articles [R. Eymard, T. Gallouet, R. Herbin, D. Hilhorst, M. Mainguy, Instantaneous and noninstantaneous Dissolution: Approximation by the finite volume method, ESAIM Proc. (1998); J. Pousin, Infinitely fast kinetics for Dissolution and diffusion in open reactive systems, Nonlinear Anal. 39 (2000) 261–279] since a precipitation and Dissolution Reaction is considered so that the Reaction term is not sign-definite and is moreover discontinuous. Energy type methods allow us to prove uniform estimates and then to study the limiting behavior of the solution as the kinetic rate tends to infinity in the special situation of one aqueous species and one solid species.

  • A fast precipitation and Dissolution Reaction for a Reaction diffusion system arising in a porous medium
    ESAIM: Mathematical Modelling and Numerical Analysis, 2007
    Co-Authors: Nicolas Bouillard, Robert Eymard, Marie Henry, Raphaele Herbin, Danielle Hilhorst
    Abstract:

    This paper is devoted to the study of a fast Reaction diffusion system arising in reactive transport. It extends previous articles since a precipitation and Dissolution Reaction is considered so that the Reaction term is not sign-definite and is moreover discontinuous. %Therefore the Reaction term is discontinuous and of unknown sign. %Monotonicity methods allow to prove uniform estimates and then to Energy type methods allow us to prove uniform estimates and then to study the limiting behavior of the solution as the kinetic rate tends to infinity in the special situation of one aqueous species and one solid species.

Nicolas Bouillard - One of the best experts on this subject based on the ideXlab platform.

  • a fast precipitation and Dissolution Reaction for a Reaction diffusion system arising in a porous medium
    Nonlinear Analysis-real World Applications, 2009
    Co-Authors: Nicolas Bouillard, Robert Eymard, Marie Henry, Raphaele Herbin, Danielle Hilhorst
    Abstract:

    Abstract This paper is devoted to the study of a fast Reaction–diffusion system arising in reactive transport. It extends the articles [R. Eymard, T. Gallouet, R. Herbin, D. Hilhorst, M. Mainguy, Instantaneous and noninstantaneous Dissolution: Approximation by the finite volume method, ESAIM Proc. (1998); J. Pousin, Infinitely fast kinetics for Dissolution and diffusion in open reactive systems, Nonlinear Anal. 39 (2000) 261–279] since a precipitation and Dissolution Reaction is considered so that the Reaction term is not sign-definite and is moreover discontinuous. Energy type methods allow us to prove uniform estimates and then to study the limiting behavior of the solution as the kinetic rate tends to infinity in the special situation of one aqueous species and one solid species.

  • A fast precipitation and Dissolution Reaction for a Reaction–diffusion system arising in a porous medium☆
    Nonlinear Analysis: Real World Applications, 2009
    Co-Authors: Nicolas Bouillard, Robert Eymard, Marie Henry, Raphaele Herbin, Danielle Hilhorst
    Abstract:

    Abstract This paper is devoted to the study of a fast Reaction–diffusion system arising in reactive transport. It extends the articles [R. Eymard, T. Gallouet, R. Herbin, D. Hilhorst, M. Mainguy, Instantaneous and noninstantaneous Dissolution: Approximation by the finite volume method, ESAIM Proc. (1998); J. Pousin, Infinitely fast kinetics for Dissolution and diffusion in open reactive systems, Nonlinear Anal. 39 (2000) 261–279] since a precipitation and Dissolution Reaction is considered so that the Reaction term is not sign-definite and is moreover discontinuous. Energy type methods allow us to prove uniform estimates and then to study the limiting behavior of the solution as the kinetic rate tends to infinity in the special situation of one aqueous species and one solid species.

  • diffusion with Dissolution and precipitation in a porous medium mathematical analysis and numerical approximation of a simplified model
    Mathematical Modelling and Numerical Analysis, 2007
    Co-Authors: Nicolas Bouillard, Robert Eymard, Raphaele Herbin, Philippe Montarnal
    Abstract:

    Modeling the kinetics of a precipitation Dissolution Reaction occurring in a porous medium where diffusion also takes place leads to a system of two parabolic equations and one ordinary differential equation coupled with a stiff Reaction term. This system is discretized by a finite volume scheme which is suitable for the approximation of the discontinuous Reaction term of unknown sign. Discrete solutions are shown to exist and converge towards a weak solution of the continuous problem. Uniqueness is proved under a Lipschitz condition on the equilibrium gap function. Numerical tests are shown which prove the efficiency of the scheme.

  • A fast precipitation and Dissolution Reaction for a Reaction diffusion system arising in a porous medium
    ESAIM: Mathematical Modelling and Numerical Analysis, 2007
    Co-Authors: Nicolas Bouillard, Robert Eymard, Marie Henry, Raphaele Herbin, Danielle Hilhorst
    Abstract:

    This paper is devoted to the study of a fast Reaction diffusion system arising in reactive transport. It extends previous articles since a precipitation and Dissolution Reaction is considered so that the Reaction term is not sign-definite and is moreover discontinuous. %Therefore the Reaction term is discontinuous and of unknown sign. %Monotonicity methods allow to prove uniform estimates and then to Energy type methods allow us to prove uniform estimates and then to study the limiting behavior of the solution as the kinetic rate tends to infinity in the special situation of one aqueous species and one solid species.

D. Bradai - One of the best experts on this subject based on the ideXlab platform.

  • A new mode of the discontinuous Dissolution Reaction in Mg-10 wt.% Al alloy
    Materials Chemistry and Physics, 2001
    Co-Authors: D. Bradai, Paweł Zięba, E. Bischoff, W. Gust
    Abstract:

    The occurrence of discontinuous precipitation (DP) and Dissolution Reactions has been investigated in Mg-10 wt.% Al alloy. The application of a special cyclic heat treatment allowed to observe a new mode of the discontinuous Dissolution Reaction. The Reaction starts preferably and occurs faster at the original locations of the grain boundaries, which is in contrast to the commonly observed behaviour where the Reaction occurs, in the early stage, primarily at the Reaction front of the former DP colonies. The proposed explanation is attributed to a characteristic movement of the Reaction front of the DP colony away from and back to the original location of the grain boundary during subsequent cycles of ageing and Dissolution.

  • The kinetics of the discontinuous precipitation and Dissolution in Mg-rich Al alloys
    Journal of Materials Science, 1999
    Co-Authors: D. Bradai, Paweł Zięba, M. Kadi-hanifi, W. M. Kuschke, W. Gust
    Abstract:

    The morphology and growth kinetics of the discontinuous precipitation and Dissolution Reactions in supersaturated Mg-Al solid solutions containing 7.3, 9.1 and 10.9 at % Al have been investigated by optical and scanning electron microscopy and X-ray measurements. The volume fraction of regions transformed by the discontinuous precipitation Reaction, the Reaction front velocity, the interlamellar spacing and the average composition of the solute-depleted lamellae were determined as a function of the temperature. For the first time, the kinetics of the discontinuous Dissolution Reaction has been studied in the Mg-Al system. It has been shown that the transport of the solute atoms during both Reactions is governed by grain boundary diffusion.

  • On the discontinuous Dissolution Reaction in a Mg-8 wt.% Al alloy
    Practical Metallography, 1998
    Co-Authors: D. Bradai, M. Kadi-hanifi, P. Zieba, W. Gust
    Abstract:

    The present studies of a Mg-8 wt.% Al alloy have shown that the discontinuous precipitation Reaction is occurring during ageing at 500 K. A subsequent Dissolution heat treatment at 625 K revealed that the Dissolution process occurs in the discontinuous mode by receding of the former Reaction front of the discontinuous precipitation towards the position of the original grain boundary. The solid solution resulting from the discontinuous Dissolution process is very inhomogeneous. As the theoretical calculations proved the differences in the Al content can be as large as 15 wt.%.

S Ronnebeck - One of the best experts on this subject based on the ideXlab platform.

  • the physics of macropore formation in low doped p type silicon
    Journal of The Electrochemical Society, 1993
    Co-Authors: Volker Lehmann, S Ronnebeck
    Abstract:

    Macropore formation in n-type silicon is a self-adjusting phenomenon characterized by a specific current density at the pore tip. At this specific current density, the Dissolution Reaction changes from the charge-transfer-limited to the mass-transfer-limited regime. The passivation of the pore walls in hydrofluoric acid is caused by a depletion of holes due to the n-type doping of the substrate. Equations based on these bindings are presented and allow us to precalculate the dimensions of the pores. The validity of the model and its mathematical description is verified in experiments