Repository logo

Browsing by Subject "CALPHAD"

Filter results by typing the first few letters
Now showing 1 - 4 of 4
  • thumbnail.journal.alt
    Item type:Article, Access status: Open Access ,
    A diffusion model of binary systems controlled by chemical potential gradient
    (AGH University Press, 2022) Wróbel, Marek; Burbelko, Andriy A.
    The paper presents a model of diffusion in a single phase with chemical potential gradient as the driving force of the process. Fick's laws are strictly empirical and the assumption that the concentration gradients are the driving forces of diffusion is far from precise. Instead, the gradient of chemical potential $\mu_{i}$ of component i is the real driving force. The matter of governing equations of models that incorporate this approach will be raised and discussed in this article. One of more important features is the ability to acquire results where diffusion against the concentration gradient may occur. The presented model uses the Finite Difference Method (FDM) and employs the CALPHAD method to obtain chemical potentials. The calculations of chemical potential are carried out for instant conditions - temperature and composition - in the entire task domain by Thermo-Calc via a TQ-Interface. Then the heterogeneity of chemical potentials is translated into mass transfer for each individual element. Calculations of two modelling tasks for one-dimension diffusion field were carried out. First: isothermal conditions with linear initial composition distribution and second: constant temperature gradient with uniform chemical composition in the specimen. Results for two binary solid solutions: Fe-C and Fe-Si, in the FCC phase for the given tasks will be presented. Modelling allows us to estimate the time needed to reach a desired state in a particular equilibrium or quasi-equilibrium state. It also shows the path of the composition change during the process. This can be used to determine whether the system at some point is getting close to the formation of another phase due to significant deviation from its initial conditions.
  • thumbnail.journal.alt
    Item type:Doctoral Dissertation, Access status: Open Access ,
    Pole naprężeń generowane dyfuzją w układzie powłoka-podłoże
    (Data obrony: 2007) Wierzba, Bartłomiej
    Wydział Inżynierii Metali i Informatyki Przemysłowej
    The model of interdiffusion for r-components system ($r \geq 2$) under the stress field is presented. It is postulated, that the overall velocity of the system is a sum of diffusional, Darken (convection) and deformation velocities. The model base on the postulate, that the diffusional flux is defined by Nernst-Planck formulae. The driving force for diffusion in such a multi component system is the gradient of the chemical and mechanical potentials. The mechanical potential can be calculated from the concentration profiles and using the known physico-chemical data of the system.
  • thumbnail.journal.alt
    Item type:Thesis, Access status: Restricted ,
  • thumbnail.journal.alt
    Item type:Article, Access status: Open Access ,
    The optimization of a numerical steel foundry simulation through a characterization of the thermal properties of the materials
    (AGH University Press, 2022) Souêtre, Morgan; Vaucheret, Alexis; Jacquet, Philippe; Carton, Jean-François
    In many foundries, numerical simulation is used to determine the origins of different defects as this tool allows the acceleration of the design process. However, the databases provided by different software do not seem to tally with the actual properties of the material. In fact, every foundry uses a different grade of steel and varying mixtures of sand. An evaluation of the impact of different material properties showed the importance of measuring every physical property to improve the database of the software. Following this, an experiment was conducted to evaluate the gap between numerical simulations and the results obtained through experimentation. This experiment, called thermal analysis, consists in measuring the solidification and cooling of a cylinder filled with liquid steel. After the calculation of the steel properties and a simulation with real experimental parameters, a comparison between each cooling curve was realized. This comparison shows that the calculated properties provide a simulated cooling curve which is closer to the experimental curve than the properties in the original database. We did not explore all of the metal properties in this study, but the modification of the sand properties was explored, together with the thermal conductivity of the steel and sand. These other measurements will be obtained in a future study.