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Jonathan Cormier - One of the best experts on this subject based on the ideXlab platform.

  • a tensorial thermodynamic framework to account for the γ rafting in nickel based single crystal superalloys
    International Journal of Plasticity, 2017
    Co-Authors: Rodrigue Desmorat, Adriana Mattiello, Jonathan Cormier
    Abstract:

    Abstract A new model is developed in order to account for the effect of microstructural degradation (i.e. precipitate-directional-coarsening) on the viscoplastic behavior of single crystal superalloys under high temperature exposure. Microstructural changes are modeled by a tensorial description of γ channel width evolution and coupled to the Kelvin modes based viscoplasticity thanks to the Orowan Stress. Such a coupling is performed within a thermodynamics framework. Isotropic and directional coarsening of the γ ' hardening phase are modeled as well as its dissolution with temperature changes. Results are presented for isothermal creep of CMSX-4 alloy at 1050 ∘ C along 001 > and 111 > crystal directions but the formulation allows to account for anisothermal loadings, isotropization of the creep response at high temperature and misaligned loadings. This newly developed tensorial framework for rafting can also apply to single crystal superalloys having a positive misfit.

  • A tensorial thermodynamic framework to account for the γ ′ rafting in Nickel-based single crystal superalloys
    2016
    Co-Authors: Rodrigue Desmorat, Adriana Mattiello, Jonathan Cormier
    Abstract:

    A new model is developed in order to account for the effect of microstructural degradation (i.e. precipitate-directional-coarsening) on the viscoplastic behavior of single crystal superalloys under high temperature exposure. Microstructural changes are modeled by a tensorial description of γ channel width evolution formulated in the natural anisotropy basis of the material. The tensorial description of microstructural evolution is combined with the Kelvin modes based viscoplasticity laws thanks to the coupling with the Orowan Stress performed within a thermodynamics framework. Isotropic and directional coarsening of the γ ′ hardening phase are modeled as well as its dissolution with temperature changes. Results are presented for isothermal creep of CMSX-4 alloy at 1050 • C along < 001 > and < 111 > crystal directions but the formulation allows to account for anisothermal loadings, isotropization of the creep response at high temperature and misaligned loadings. This newly developed tensorial framework for rafting can also apply to single crystal superalloys having a positive misfit.

  • creep behavior under isothermal and non isothermal conditions of am3 single crystal superalloy for different solutioning cooling rates
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014
    Co-Authors: S Steuer, Zeline Hervier, S Thabart, C Castaing, Tresa M Pollock, Jonathan Cormier
    Abstract:

    Abstract Isothermal and non-isothermal creep experiments are performed using AM3 Ni-based single crystal samples which were cooled from the solutioning temperature during heat treatment with different cooling rates. Cooling rates from the solution temperature influenced the precipitate size and distribution and influenced creep properties, with creep lifetimes increasing and secondary creep rates decreasing with faster cooling rates. Up to a cooling rate of about 100 °C/min, the microstructure is very inhomogeneous and the γ ׳-particles exhibit an irregular shape and are partially large in size. For the fastest cooling rate (300 °C/min), the microstructure consists of ordered cubic γ ׳-precipitates surrounded by narrow γ -channels. According to Orowan Stress calculations, the investigated creep properties under both isothermal and non-isothermal conditions seem to be mainly controlled by the resistance to dislocation bowing in the γ -channels.

Rodrigue Desmorat - One of the best experts on this subject based on the ideXlab platform.

  • a tensorial thermodynamic framework to account for the γ rafting in nickel based single crystal superalloys
    International Journal of Plasticity, 2017
    Co-Authors: Rodrigue Desmorat, Adriana Mattiello, Jonathan Cormier
    Abstract:

    Abstract A new model is developed in order to account for the effect of microstructural degradation (i.e. precipitate-directional-coarsening) on the viscoplastic behavior of single crystal superalloys under high temperature exposure. Microstructural changes are modeled by a tensorial description of γ channel width evolution and coupled to the Kelvin modes based viscoplasticity thanks to the Orowan Stress. Such a coupling is performed within a thermodynamics framework. Isotropic and directional coarsening of the γ ' hardening phase are modeled as well as its dissolution with temperature changes. Results are presented for isothermal creep of CMSX-4 alloy at 1050 ∘ C along 001 > and 111 > crystal directions but the formulation allows to account for anisothermal loadings, isotropization of the creep response at high temperature and misaligned loadings. This newly developed tensorial framework for rafting can also apply to single crystal superalloys having a positive misfit.

  • A tensorial thermodynamic framework to account for the γ ′ rafting in Nickel-based single crystal superalloys
    2016
    Co-Authors: Rodrigue Desmorat, Adriana Mattiello, Jonathan Cormier
    Abstract:

    A new model is developed in order to account for the effect of microstructural degradation (i.e. precipitate-directional-coarsening) on the viscoplastic behavior of single crystal superalloys under high temperature exposure. Microstructural changes are modeled by a tensorial description of γ channel width evolution formulated in the natural anisotropy basis of the material. The tensorial description of microstructural evolution is combined with the Kelvin modes based viscoplasticity laws thanks to the coupling with the Orowan Stress performed within a thermodynamics framework. Isotropic and directional coarsening of the γ ′ hardening phase are modeled as well as its dissolution with temperature changes. Results are presented for isothermal creep of CMSX-4 alloy at 1050 • C along < 001 > and < 111 > crystal directions but the formulation allows to account for anisothermal loadings, isotropization of the creep response at high temperature and misaligned loadings. This newly developed tensorial framework for rafting can also apply to single crystal superalloys having a positive misfit.

Curt A Bronkhorst - One of the best experts on this subject based on the ideXlab platform.

  • crystal plasticity model for single crystal ni based superalloys capturing orientation and temperature dependence of flow Stress
    International Journal of Plasticity, 2021
    Co-Authors: Satyapriya Gupta, Curt A Bronkhorst
    Abstract:

    Abstract We develop a dislocation density based crystal plasticity model to capture the micromechanical behavior of γ′ strengthening nickel-based superalloys. The elasto-viscoplastic model presented here accounts for hardening behavior of both γ and γ′ which are the two phases considered in the present work. The model includes multiple strengthening mechanisms such as Orowan Stress, evolving slip resistance caused by dislocation interactions, and γ′ structural contribution to initial slip resistance. Interaction between γ and γ′, a key feature of these alloys has been modelled in terms of back Stress induced by dislocation pileup or looping around the large γ′ precipitates. Furthermore, anti-phase boundary (APB) shearing is considered as the dominant deformation mechanism for shearable γ′ precipitates. In addition to octahedral {111}⟨110⟩ slip, the model also accounts for cube slip systems {100}⟨110⟩ which are known to be instrumental in γ′ shearing and introducing flow Stress orientation dependence. Temperature dependence of the initial slip resistance is fitted against experimental observation of anomalous yielding for two different single crystal orientations. An optimization procedure based on the minimization of the error between simulated and experimental Stress strain curves, is adopted to evaluate a selected group of material parameters. Subsequently, proper working of the model is tested against an independent set of single crystal experimental data available for CMSX-4 around service temperature and MD2 at room temperature. The model also represents a strong orientation dependence of yield Stress anomaly (YSA), a salient feature of Ni-based superalloys.

Adriana Mattiello - One of the best experts on this subject based on the ideXlab platform.

  • a tensorial thermodynamic framework to account for the γ rafting in nickel based single crystal superalloys
    International Journal of Plasticity, 2017
    Co-Authors: Rodrigue Desmorat, Adriana Mattiello, Jonathan Cormier
    Abstract:

    Abstract A new model is developed in order to account for the effect of microstructural degradation (i.e. precipitate-directional-coarsening) on the viscoplastic behavior of single crystal superalloys under high temperature exposure. Microstructural changes are modeled by a tensorial description of γ channel width evolution and coupled to the Kelvin modes based viscoplasticity thanks to the Orowan Stress. Such a coupling is performed within a thermodynamics framework. Isotropic and directional coarsening of the γ ' hardening phase are modeled as well as its dissolution with temperature changes. Results are presented for isothermal creep of CMSX-4 alloy at 1050 ∘ C along 001 > and 111 > crystal directions but the formulation allows to account for anisothermal loadings, isotropization of the creep response at high temperature and misaligned loadings. This newly developed tensorial framework for rafting can also apply to single crystal superalloys having a positive misfit.

  • A tensorial thermodynamic framework to account for the γ ′ rafting in Nickel-based single crystal superalloys
    2016
    Co-Authors: Rodrigue Desmorat, Adriana Mattiello, Jonathan Cormier
    Abstract:

    A new model is developed in order to account for the effect of microstructural degradation (i.e. precipitate-directional-coarsening) on the viscoplastic behavior of single crystal superalloys under high temperature exposure. Microstructural changes are modeled by a tensorial description of γ channel width evolution formulated in the natural anisotropy basis of the material. The tensorial description of microstructural evolution is combined with the Kelvin modes based viscoplasticity laws thanks to the coupling with the Orowan Stress performed within a thermodynamics framework. Isotropic and directional coarsening of the γ ′ hardening phase are modeled as well as its dissolution with temperature changes. Results are presented for isothermal creep of CMSX-4 alloy at 1050 • C along < 001 > and < 111 > crystal directions but the formulation allows to account for anisothermal loadings, isotropization of the creep response at high temperature and misaligned loadings. This newly developed tensorial framework for rafting can also apply to single crystal superalloys having a positive misfit.

Takahiro Hatano - One of the best experts on this subject based on the ideXlab platform.

  • dynamics of a dislocation bypassing an impenetrable precipitate the hirsch mechanism revisited
    Physical Review B, 2006
    Co-Authors: Takahiro Hatano
    Abstract:

    The dynamical process where an edge dislocation in fcc copper bypasses an impenetrable precipitate is investigated by means of molecular dynamics simulation. A mechanism that is quite different from the Orowan mechanism is observed, where a dislocation leaves two prismatic loops near a precipitate, i.e., the Hirsch mechanism. It is found that the critical Stress for the Hirsch mechanism is almost the same as the Orowan Stress, while spatial inhomogeneity of the shear Stress is essential to the Hirsch mechanism. We also find that repetition of the Hirsch mechanism does not increase the critical Stress.