Dresden 2017 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 6: Structural Materials
MM 6.1: Vortrag
Montag, 20. März 2017, 10:15–10:30, IFW D
Ordering and thermodynamic properties of refractory NbMoTaW alloy from first-principles — •Fritz Körmann1, Andrei V. Ruban2,3, and Marcel H.F. Sluiter1 — 1Materials Science and Engineering, Delft University of Technology, Delft, Netherlands. — 2Materials Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden. — 3Materials Center Leoben, Leoben, Austria.
Some refractory high entropy alloys (HEA) exhibit high-temperature mechanical properties that exceed modern Ni-based super alloys. However, little is known about their fundamental physical properties such as, e.g. ground states, degree of chemical ordering at elevated temperatures or thermodynamic properties. We present a combined first-principles and Monte Carlo (MC) study to investigate ordering at elevated temperatures in the prototype BCC HEA NbMoTaW [1]. Chemical interactions have been computed from first-principles by means of the coherent potential approximation in combination with the screened generalized perturbation method. Local relaxations have been considered by explicit super cell calculations. Surprisingly, the NbMoTaW solid-solution at elevated temperatures does not originate from the small magnitude but rather from the highly frustrated long-ranged nature of the chemical interactions. The role of the chemical interactions and ordering on thermodynamic properties is examined in detail [2]. [1] F. Körmann, A.V. Ruban, M.H.F. Sluiter, Materials Research Letters (2016), DOI 0.1080/21663831.2016.1198837 [2] F. Körmann, M.H.F. Sluiter, Entropy 18, 403 (2016).