Title:	Ab initio and classical atomistic modelling of refractory metals and hydrides
DNr:	SNIC 2021/5-467
Project Type:	SNIC Medium Compute
Principal Investigator:	Pär Olsson <par.olsson@mau.se>
Affiliation:	Malmö universitet
Duration:	2021-11-01 – 2022-11-01
Classification:	10304
Keywords:

Abstract

The purpose of this project is to investigate (i) the impact of impurities on tungsten grain boundary strength, (ii) the impact of transmutation products on the mechanical properties of tungsten and (iii) the mechanical and vibrational properties of uranium, titanium and zirconium hydrides. For the grain boundary modelling of tungsten we will use both DFT and classical atomistic modelling. Typically we intend to investigate how impurities affect the cohesive strength of grain boundaries. This effort requires the modelling of slip and brittle mechanisms for large supercells. For investigating the impact of transmutation products on the mechanical properties of tungsten we will rely on both classical atomistic modelling and DFT modelling. Our focus is to study the role of W-Re and W-Os precipitates on the hardening of tungsten employed in fusion reactors. We will use DFT in conjunction with potfit to generate empirical binary potentials that will be used to investigate the glide of dislocations in the presence of both coherent, semi-coherent and incoherent precipitates. This aims to provide data to parameterize the Bacon-Kochs-Scattergood (BKS) relation that will be used for macroscopic modelling to quantify the precipitate hardening effect. The third project comprises two parts: (i) we will compute the phonon spectra of uranium, and zirconium hydrides and (ii) investigate the impact of hydride precipitates on the dislocation glide mechanisms in the aforementioned hydrides, along with titanium hydrides. The first part of the project aims to support experimental activities associated to using ultra-cold neutrons for characterizing the hydrogen content in hydrides. The experimental activities will be performed under the supervision of Dr. Takeyasu Ito at the Neutron Science Center at Los Alamos Science Lab, while the researchers in Lund and Malmö will support the experimental activities with first-principles DFT data regarding phonon and thermodynamic properties. Of special interest are uranium hydrides (UHx) and zirconium hydrides (ZrHx). For the second part we will generate new binary potentials and investigate the dislocation mobility in the presence of precipitates. We will use the force-matching method to generate the new potentials. This parametrization approach aims to reproduce energies and forces as derived from DFT.