Spinodal Decomposition

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Xiaoqin Yang - One of the best experts on this subject based on the ideXlab platform.

  • Concurrence of Spinodal Decomposition and nano-phase precipitation in a multi-component AlCoCrCuFeNi high-entropy alloy
    2019
    Co-Authors: Yue Zhang, Zheng Chen, Dongdong Cao, Jinyong Zhang, Ping Zhang, Qing Tao, Xiaoqin Yang
    Abstract:

    The concurrence of Spinodal Decomposition and nano-phase precipitation in an AlCoCrCuFeNi high-entropy alloy produced by arc melting, spray casting and melt spinning was investigated in the present work. It is shown that the present high cooling rate cannot inhibit the concurrence of Spinodal Decomposition and nano-phase precipitation. In the solidification and annealing process, three typical structures including Cu-rich nano-precipitates of FCC structure, Al-Ni-rich plate of B2 structure, and Fe-Cr-rich plate of A2 structure were observed; meanwhile, the width of modulated plate decreased with the increase of the cooling rate. An interesting phenomenon was observed in the as-annealed microstructure that Al-Ni and Fe-Cr Spinodal plates were weakened or vanished rather than strengthened, due to the atom diffusion and composition homogenization. Different from Spinodal Decomposition plates, the Cu-rich nano-precipitates grew into rod-like phase from point-like or oval phase in the whole process. The intersection angle of newborn rod-like nano-phases tended to 60°, following the K-S crystallographic relationship. Keywords: Spinodal Decomposition, Nano-phase precipitation, High-entropy allo

  • concurrence of Spinodal Decomposition and nano phase precipitation in a multi component alcocrcufeni high entropy alloy
    2019
    Co-Authors: Yue Zhang, Zheng Chen, Dongdong Cao, Jinyong Zhang, Ping Zhang, Qing Tao, Xiaoqin Yang
    Abstract:

    Abstract The concurrence of Spinodal Decomposition and nano-phase precipitation in an AlCoCrCuFeNi high-entropy alloy produced by arc melting, spray casting and melt spinning was investigated in the present work. It is shown that the present high cooling rate cannot inhibit the concurrence of Spinodal Decomposition and nano-phase precipitation. In the solidification and annealing process, three typical structures including Cu-rich nano-precipitates of FCC structure, Al-Ni-rich plate of B2 structure, and Fe-Cr-rich plate of A2 structure were observed; meanwhile, the width of modulated plate decreased with the increase of the cooling rate. An interesting phenomenon was observed in the as-annealed microstructure that Al-Ni and Fe-Cr Spinodal plates were weakened or vanished rather than strengthened, due to the atom diffusion and composition homogenization. Different from Spinodal Decomposition plates, the Cu-rich nano-precipitates grew into rod-like phase from point-like or oval phase in the whole process. The intersection angle of newborn rod-like nano-phases tended to 60°, following the K-S crystallographic relationship.

Yue Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Concurrence of Spinodal Decomposition and nano-phase precipitation in a multi-component AlCoCrCuFeNi high-entropy alloy
    2019
    Co-Authors: Yue Zhang, Zheng Chen, Dongdong Cao, Jinyong Zhang, Ping Zhang, Qing Tao, Xiaoqin Yang
    Abstract:

    The concurrence of Spinodal Decomposition and nano-phase precipitation in an AlCoCrCuFeNi high-entropy alloy produced by arc melting, spray casting and melt spinning was investigated in the present work. It is shown that the present high cooling rate cannot inhibit the concurrence of Spinodal Decomposition and nano-phase precipitation. In the solidification and annealing process, three typical structures including Cu-rich nano-precipitates of FCC structure, Al-Ni-rich plate of B2 structure, and Fe-Cr-rich plate of A2 structure were observed; meanwhile, the width of modulated plate decreased with the increase of the cooling rate. An interesting phenomenon was observed in the as-annealed microstructure that Al-Ni and Fe-Cr Spinodal plates were weakened or vanished rather than strengthened, due to the atom diffusion and composition homogenization. Different from Spinodal Decomposition plates, the Cu-rich nano-precipitates grew into rod-like phase from point-like or oval phase in the whole process. The intersection angle of newborn rod-like nano-phases tended to 60°, following the K-S crystallographic relationship. Keywords: Spinodal Decomposition, Nano-phase precipitation, High-entropy allo

  • concurrence of Spinodal Decomposition and nano phase precipitation in a multi component alcocrcufeni high entropy alloy
    2019
    Co-Authors: Yue Zhang, Zheng Chen, Dongdong Cao, Jinyong Zhang, Ping Zhang, Qing Tao, Xiaoqin Yang
    Abstract:

    Abstract The concurrence of Spinodal Decomposition and nano-phase precipitation in an AlCoCrCuFeNi high-entropy alloy produced by arc melting, spray casting and melt spinning was investigated in the present work. It is shown that the present high cooling rate cannot inhibit the concurrence of Spinodal Decomposition and nano-phase precipitation. In the solidification and annealing process, three typical structures including Cu-rich nano-precipitates of FCC structure, Al-Ni-rich plate of B2 structure, and Fe-Cr-rich plate of A2 structure were observed; meanwhile, the width of modulated plate decreased with the increase of the cooling rate. An interesting phenomenon was observed in the as-annealed microstructure that Al-Ni and Fe-Cr Spinodal plates were weakened or vanished rather than strengthened, due to the atom diffusion and composition homogenization. Different from Spinodal Decomposition plates, the Cu-rich nano-precipitates grew into rod-like phase from point-like or oval phase in the whole process. The intersection angle of newborn rod-like nano-phases tended to 60°, following the K-S crystallographic relationship.

Mohamed Laradji - One of the best experts on this subject based on the ideXlab platform.

  • dissipative particle dynamics simulation of the interplay between Spinodal Decomposition and wetting in thin film binary fluids
    2010
    Co-Authors: Michael J A Hore, Mohamed Laradji
    Abstract:

    The dynamics of phase separation of thin film binary fluids is investigated via dissipative particle dynamics simulation. We consider both cases of symmetric and asymmetric interactions between the walls and the two components. In the case of walls interacting symmetrically with the two fluid components, corresponding to a nonwetting case, relatively fast kinetics is observed when the average domain size is smaller than the slit thickness. A crossover to a slow Lifshitz–Slyozov growth is observed at late times. Faster dynamics is observed when the walls act as a slip boundary condition to the velocity field. In the case of asymmetric interactions, such that the system is in the wetting regime, the interplay between wetting kinetics and Spinodal Decomposition leads to rich dynamics. The phase separation proceeds through three stages. During the first stage, the dynamics is characterized as surface-directed Spinodal Decomposition, with growth of both average domain size and thickness of the wetting layers. ...

  • molecular dynamics simulation of Spinodal Decomposition in three dimensional binary fluids
    1996
    Co-Authors: Mohamed Laradji, Soren Toxvaerd, Ole G Mouritsen
    Abstract:

    Using large-scale molecular dynamics simulations of a two-component Lennard-Jones model in three dimensions, we show that the late-time dynamics of Spinodal Decomposition in concentrated binary fluids reaches a viscous scaling regime with a growth exponent $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$, in agreement with experiments and a theoretical analysis for viscous growth.

Jurn W P Schmelzer - One of the best experts on this subject based on the ideXlab platform.

  • nucleation versus Spinodal Decomposition in confined binary solutions
    2007
    Co-Authors: Alexander S Abyzov, Jurn W P Schmelzer
    Abstract:

    Basic features of Spinodal Decomposition, on one side, and nucleation, on the other side, and the transition between both mechanisms are analyzed within the framework of a generalized thermodynamic cluster model based on the generalized Gibbs approach. Hereby the clusters, representing the density or composition variations in the system, may change with time both in size and in their intensive state parameters (density and composition, for example). In the first part of the analysis, we consider phase separation processes in dependence on the initial state of the system for the case when changes of the state parameters of the ambient system due to the evolution of the clusters can be neglected as this is the case for cluster formation in an infinite system. As a next step, the effect of changes of the state parameters on cluster evolution is analyzed. Such depletion effects are of importance both for the analysis of phase formation in confined systems and for the understanding of the evolution of ensembles of clusters in large (in the limit infinite) systems. The results of the thermodynamic analysis are employed in both cases to exhibit the effect of thermodynamic constraints on the dynamics of phase separation processes.

  • nucleation versus Spinodal Decomposition in phase formation processes in multicomponent solutions
    2004
    Co-Authors: Jurn W P Schmelzer, Alexander S Abyzov, J Moller
    Abstract:

    In the present paper, some further results of application of the generalized Gibbs’ approach [J. W. P. Schmelzer et al., J. Chem. Phys. 112, 3820 (2000); 114, 5180 (2001); 119, 6166 (2003)] to describing new-phase formation processes are outlined. The path of cluster evolution in size and composition space is determined taking into account both thermodynamic and kinetic factors. The basic features of these paths of evolution are discussed in detail for a simple model of a binary mixture. According to this analysis, size and composition of the clusters of the newly evolving phase change in an unexpected way which is qualitatively different as compared to the classical picture of nucleation-growth processes. As shown, nucleation (i.e., the first stage of cluster formation starting from metastable initial states) exhibits properties resembling Spinodal Decomposition (the size remains nearly constant while the composition changes) although the presence of an activation barrier distinguishes the nucleation process from true Spinodal Decomposition. In addition, it is shown that phase formation both in metastable and unstable initial states near the classical Spinodal may proceed via a passage of a ridge of the thermodynamic potential with a finite work of the activation barrier even though (for unstable initial states) the value of the work of critical cluster formation (corresponding to the saddle point of the thermodynamic potential) is zero. This way, it turns out that nucleation concepts—in a modified form as compared with the classical picture—may govern also phase formation processes starting from unstable initial states. In contrast to the classical Gibbs’ approach, the generalized Gibbs’ method provides a description of phase changes both in binodal and Spinodal regions of the phase diagram and confirms the point of view assuming a continuity of the basic features of the phase transformation kinetics in the vicinity of the classical Spinodal curve.

E M Terentjev - One of the best experts on this subject based on the ideXlab platform.

  • arrested Spinodal Decomposition in polymer brush collapsing in poor solvent
    2015
    Co-Authors: Anna Lappala, Saahil Mendiratta, E M Terentjev
    Abstract:

    We study the Brownian dynamics of flexible and semiflexible polymer chains densely grafted on a flat substrate upon rapid quenching of the system when the quality of solvent becomes poor and chains attempt collapse into a globular state. The collapse process of such a polymer brush differs from individual chains, both in its kinetics and its structural morphology. We find that the resulting collapsed brush does not form a homogeneous dense layer, in spite of all chain monomers equally attracting each other via a model Lennard-Jones potential. Instead, a very distinct inhomogeneous density distribution in the plane forms, with a characteristic length scale dependent on the quenching depth (or, equivalently, the strength of monomer attraction) and the geometric parameters of the brush. This structure is identical to the Spinodal-Decomposition structure; however, due to the grafting constraint we find no subsequent coarsening: the established random bundling with characteristic periodicity remains as the app...

  • arrested Spinodal Decomposition in polymer brush collapsing in poor solvent
    2014
    Co-Authors: Anna Lappala, Saahil Mendiratta, E M Terentjev
    Abstract:

    We study the Brownian dynamics of flexible and semiflexible polymer chains densely grafted on a flat substrate, upon rapid quenching of the system when the quality of solvent becomes poor and chains attempt collapse into a globular state. The collapse process of such a polymer brush differs from individual chains, both in its kinetics and its structural morphology. We find that the resulting collapsed brush does not form a homogeneous dense layer, in spite of all chain monomers equally attracting each other via a model Lennard-Jones potential. Instead, a very distinct inhomogeneous density distribution in the plane forms, with a characteristic length scale dependent on the quenching depth (or equivalently, the strength of monomer attraction) and the geometric parameters of the brush. This structure is identical to the Spinodal-Decomposition structure, however, due to the grafting constraint we find no subsequent coarsening: the established random bundling with characteristic periodicity remains as the apparently equilibrium structure. We compare this finding with a recent field-theoretical model of bundling in a semiflexible polymer brush.