The Experts below are selected from a list of 2064 Experts worldwide ranked by ideXlab platform

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

  • Effect of Thermal Vacancy on Thermodynamic Behaviors in BCC W Close to Melting Point: A Thermodynamic Study
    Materials, 2018
    Co-Authors: Ying Tang, Lijun Zhang
    Abstract:

    As temperature increases, the Thermal Vacancy Concentration in pure metals dramatically increases and causes some strongly non-linear thermodynamic behaviors in pure metals when close to their melting points. In this paper, we chose body-centered cubic (bcc) W as the target and presented a thermodynamic model to account for its Gibbs energy of pure bcc W from 0 K to melting point by including the contribution of Thermal Vacancy. A new formula for interaction part was proposed for describing the quadratic temperature behavior of Vacancy formation energy. Based on the experimental/first-principles computed thermodynamic properties, all the parameters in the Gibbs energy function were assessed by following the proposed two-step optimization strategy. The thermodynamic behaviors, i.e., the strong nonlinear increase for temperature dependence of heat capacities at high temperatures and a nonlinear Arrhenius plot of Vacancy Concentration, in bcc W can be well reproduced by the obtained Gibbs energy. The successful description of Thermal Vacancy on such strongly non-linear thermodynamic behaviors in bcc W indicates that the presently proposed thermodynamic model and optimization strategy should be universal ones and are applicable to all other metals.

Daniel Monceau - One of the best experts on this subject based on the ideXlab platform.

  • impact of the clusterization on the solubility of oxygen and Vacancy Concentration in nickel a multi scale approach
    Journal of Alloys and Compounds, 2017
    Co-Authors: Damien Connetable, Matthieu David, Aurelien Prillieux, David J Young, Daniel Monceau
    Abstract:

    Combining thermodynamic concepts with first-principles calculations, we study the solubility of oxygen atoms (O) in nickel. In our approach, we include the possible formation of oxygen clusters (On) and vacancies-oxygens clusters (VOn and V2On). We show that the Vacancy-oxygens interactions are strong (approximately 1 eV) and would induce a large Concentration of clusters in fcc-Ni. The use of a thermodynamic model, within a grand canonical approach, allows calculation of the Vacancy Concentration, including these VOn clusters, as a function of O Concentration, for different temperatures. We find that at low temperatures (below 600 K), a small content of oxygen (in appm) strongly modifies the Vacancy Concentration, increasing the total Vacancy Concentration in the metal by many orders of magnitude more than the Thermal Vacancy Concentration. The Vacancy Concentration is thus directly controlled by the oxygen content in the metal. At high temperatures, the effect is reduced, becoming negligible near the melting point. These results show the strong impact of interstitial atoms on the Vacancy Concentration. The influence of the Vacancy formation energy is also discussed.

Ying Tang - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Thermal Vacancy on Thermodynamic Behaviors in BCC W Close to Melting Point: A Thermodynamic Study
    Materials, 2018
    Co-Authors: Ying Tang, Lijun Zhang
    Abstract:

    As temperature increases, the Thermal Vacancy Concentration in pure metals dramatically increases and causes some strongly non-linear thermodynamic behaviors in pure metals when close to their melting points. In this paper, we chose body-centered cubic (bcc) W as the target and presented a thermodynamic model to account for its Gibbs energy of pure bcc W from 0 K to melting point by including the contribution of Thermal Vacancy. A new formula for interaction part was proposed for describing the quadratic temperature behavior of Vacancy formation energy. Based on the experimental/first-principles computed thermodynamic properties, all the parameters in the Gibbs energy function were assessed by following the proposed two-step optimization strategy. The thermodynamic behaviors, i.e., the strong nonlinear increase for temperature dependence of heat capacities at high temperatures and a nonlinear Arrhenius plot of Vacancy Concentration, in bcc W can be well reproduced by the obtained Gibbs energy. The successful description of Thermal Vacancy on such strongly non-linear thermodynamic behaviors in bcc W indicates that the presently proposed thermodynamic model and optimization strategy should be universal ones and are applicable to all other metals.

Damien Connetable - One of the best experts on this subject based on the ideXlab platform.

  • impact of the clusterization on the solubility of oxygen and Vacancy Concentration in nickel a multi scale approach
    Journal of Alloys and Compounds, 2017
    Co-Authors: Damien Connetable, Matthieu David, Aurelien Prillieux, David J Young, Daniel Monceau
    Abstract:

    Combining thermodynamic concepts with first-principles calculations, we study the solubility of oxygen atoms (O) in nickel. In our approach, we include the possible formation of oxygen clusters (On) and vacancies-oxygens clusters (VOn and V2On). We show that the Vacancy-oxygens interactions are strong (approximately 1 eV) and would induce a large Concentration of clusters in fcc-Ni. The use of a thermodynamic model, within a grand canonical approach, allows calculation of the Vacancy Concentration, including these VOn clusters, as a function of O Concentration, for different temperatures. We find that at low temperatures (below 600 K), a small content of oxygen (in appm) strongly modifies the Vacancy Concentration, increasing the total Vacancy Concentration in the metal by many orders of magnitude more than the Thermal Vacancy Concentration. The Vacancy Concentration is thus directly controlled by the oxygen content in the metal. At high temperatures, the effect is reduced, becoming negligible near the melting point. These results show the strong impact of interstitial atoms on the Vacancy Concentration. The influence of the Vacancy formation energy is also discussed.

Matthieu David - One of the best experts on this subject based on the ideXlab platform.

  • impact of the clusterization on the solubility of oxygen and Vacancy Concentration in nickel a multi scale approach
    Journal of Alloys and Compounds, 2017
    Co-Authors: Damien Connetable, Matthieu David, Aurelien Prillieux, David J Young, Daniel Monceau
    Abstract:

    Combining thermodynamic concepts with first-principles calculations, we study the solubility of oxygen atoms (O) in nickel. In our approach, we include the possible formation of oxygen clusters (On) and vacancies-oxygens clusters (VOn and V2On). We show that the Vacancy-oxygens interactions are strong (approximately 1 eV) and would induce a large Concentration of clusters in fcc-Ni. The use of a thermodynamic model, within a grand canonical approach, allows calculation of the Vacancy Concentration, including these VOn clusters, as a function of O Concentration, for different temperatures. We find that at low temperatures (below 600 K), a small content of oxygen (in appm) strongly modifies the Vacancy Concentration, increasing the total Vacancy Concentration in the metal by many orders of magnitude more than the Thermal Vacancy Concentration. The Vacancy Concentration is thus directly controlled by the oxygen content in the metal. At high temperatures, the effect is reduced, becoming negligible near the melting point. These results show the strong impact of interstitial atoms on the Vacancy Concentration. The influence of the Vacancy formation energy is also discussed.