Berlin 2018 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 69: Structural Materials (Steels, light-weight materials, high-temperature materials)

MM 69.3: Talk

Friday, March 16, 2018, 10:00–10:15, H 0106

Chromium and iron based zeta phases - lattice dynamics from first-principles — •Petr Dvořáček and Dominik Legut — VSB Technical University of Ostrava

It was shown [1] that the Z-phase precipitates at higher rate in Cr-rich steels than in Cr-depleted ones and this precipitation correlates with the presence of Niobium. Recently, the lectronic structure and mechanical properties of Z-phases, namely CrNbN and CrVN, were investigated employing first-principles calculations [2]. In this contributions we extend our understanding for dynamical and thermodynamical properties of the Cr-(V/Nb/Mo)-N and Fe-(V/Nb/Mo)-N Z-phases based on the lattice vibrations computed within the quasi-harmonic approximations[3]. The requested Hellman-Feynman forces acting on atoms along the atomic vibrations were computed emlopying density functional theory via the Vienna Ab Initio Simulation package[4]. The results are following: CrNbN, CrVN, CrNbVN, FeNbN, FeNbVN are thermodynamically stable, CrMoN, FeVN are thermodynamically unstable, but are stable in gamma-point and FeMoN is completely thermodynamically unstable.

References: 1. H. K. Danielsen and J. Hald, Energy Mater. 1, 49 (2006). 2. D. Legut and J. Pavlů, J. Phys.: Condens. Matter. 24 , 195502 (2012). 3. A. Togo and I. Tanaka, Scr. Mater., 108, 1-5 (2015). 4. G. Kresse and J. Furthmueller, Comput. Mater. Sci. 6, 15 (1996).

This work was supported by Czech National Foundation grant No. 17-27790S and Path to Exascale project No. CZ.02.1.01/0.0/0.0/16_013/0001791.