Speaker
Description
Several intermetallic phases are important in the design of Nickelbase superalloys: The $\gamma'$-phase (Ni3Al) and $\gamma''$-phase (Ni3Nb) provide strengthening whereas the $\delta$-phase (Ni3Nb) and $\eta$-phase (Ni3Ti) are important in ensuring a fine-grained structure in wrought alloys, but may also be detrimental because they may embrittle the alloy.
The solution energies of all transition elements in all possible positions of the four phases are calculated. It is shown that it is possible to model these energies using two quantities, the Bader charge and the atomic volume in a nickel matrix. We also show how a high concentration of Cr or Co in the matrix stabilizes these phases by increasing the energy of the phase-forming element in the matrix. Finally, we discuss the influence of magnetic effects and provide some insights in how to overcome convergence problems.
References:
BÄKER, Martin, et al. Influence of transition group elements on the stability of the δ-and η-phase in nickelbase alloys. Modelling and Simulation in Materials Science and Engineering, 2017, 26. Jg., Nr. 1, S. 015005.
BÄKER, Martin; RÖSLER, Joachim. Influence of transition group elements on the stability of the γ ″-phase in nickelbase alloys. Modelling and Simulation in Materials Science and Engineering, 2021, 29. Jg., Nr. 5, S. 055006.
BÄKER, Martin; RÖSLER, Joachim. Effect of Co and Cr on the Stability of Strengthening Phases in Nickelbase Superalloys. Crystals, 2022, 12. Jg., Nr. 8, S. 1084.
