Title:	Impurity Segregations at Extended Defects in High-performance Materials
DNr:	SNIC 2019/3-36
Project Type:	SNIC Medium Compute
Principal Investigator:	Pavel Korzhavyi <pavelk@kth.se>
Affiliation:	Kungliga Tekniska högskolan
Duration:	2019-01-29 – 2020-02-01
Classification:	20506 10402 10304
Homepage:	http://www.hero-m.mse.kth.se/
Keywords:

Abstract

The purpose of this proposal is to allocate supercomputer resources to the planned studies in the Generic Ab-initio project within the Vinnova Competence Center “Hierarchic Engineering of Industrial Materials” (Hero-m 2 Innovation, Grant No.2016-00668), 2017-2022. Funding: Vinnova, Swedish Industry and KTH. The Hero-m 2i Consortium is a joint venture between KTH and industry. The Generic Ab-initio project involves industrial partners from Thermo-Calc Software and Sandvik. Several tasks are motivated by Svensk Kärnbränslehantering AB (SKB) and Swerim. Solute segregations and other defect arrangements may have beneficial or detrimental effects in the properties of high-performance materials. To enable for predictive modeling if such effects, the project deals with computational studies of defects (ranging from point defects such as vacancies and impurities to planar defects such as surfaces and interfaces), defect interactions, and defect arrangements in the main phases of industrially relevant materials: steels, aluminum and copper alloys, superalloys, and ceramic materials. These studies are to provide data on the atomic-level structures and mechanisms that are important for understanding and controlling the thermodynamic, mechanical, and kinetic properties. We adopt an integrated computational modeling approach, based on quantum mechanics and statistical physics and starting from electronic and atomic levels and passing the data to semi-discrete and continuum methods that operate at longer length- and time-scales. Within this approach, we have developed efficient theoretical tools for describing the thermodynamic and kinetic properties of materials at elevated temperatures. These methods enable computer-aided optimization of the compositions and the heat treatment regimes of new grades of steel, superalloys, and refractory ceramics, with the goal to adapt these materials to novel applications in which an unusual combination of properties may be required. Research plan: WP-1: Lattice defects Task 1.1: To continue our systematic studies of point defects (impurities, vacancies, intersititials, and their clusters) and their diffusion in alloys and compounds. Task 1.2: To model the structure and dynamics of extended lattice defects (grain boundaries, coherent and semi-coherent phase interfaces, and dislocations) in metals and alloys. Task 1.3: To perform ab initio based multi-scale modeling of segregation phenomena at selected dislocations, interfaces, and grain boundaries. To model the effect of segregations on dislocation mobility, grain boundary sliding, and grain boundary cohesion in Al-, Cu-, and Ni-based alloys. WP-2: High-performance alloy phases Task 2.1: To perform ab-initio based atomistic modeling of Ni-based solid solutions (single-phase superalloys) and point-defect interactions and clustering in these alloys at finite temperatures. Task 2.2: To perform high-throughput calculations of the physical properties of end member compounds, with the goal to formulate compound energy models of fcc solid solutions in industrially relevant multicomponent alloys of d-transition metals, sp- metals and metalloid elements. Task 2.3: To perform case studies of the electronic and atomic structure of complex intermetallic compounds (e.g., Laves phases), as well as metal-metalloid compounds such as carbides and nitrides.