Title: Helium segregation to screw and edge dislocations in α-iron and their yield strength

Abstract

Helium (He) introduces one of the mayor concerns in the nuclear materials community as it modifies the mechanical properties of the system withstanding fast neutron spectra, promoting swelling and embrittlement. Ferritic/martensitic steels are one of the main candidates as structural materials for future nuclear applications. Experimentally the bubble distribution is observed to vary depending on irradiation conditions (temperature, dose rate and total dose). However, traditional atomistic models decouple the role of temperature in the mechanical properties from its effect on the bubble distribution. In this paper we study substitutional He segregation to screw and edge dislocations in α-Fe at different temperatures. We use an object kinetic Monte Carlo methodology to obtain general trends in bubble distribution and a canonical Monte Carlo algorithm, with full atomistic fidelity, to find the He distribution at the dislocation cores. Molecular dynamics has subsequently been applied to study the yield strength, which increases significantly in the presence of He, more remarkably for the edge dislocation. The total stress fits a Kocks relation. Yet, if the lattice resistance is subtracted, the relation between the critical shear stress and the temperature is non-monotonic for the screw character. To reproduce this effect, we propose to modify the Kocksmore » relation, adding a second-order term in temperature that extends the range of applicability of the model.« less

Authors:

Martínez, Enrique ^[1]; Schwen, Daniel ^[1]; Caro, Alfredo ^[1]

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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:

Wed Nov 26 00:00:00 EST 2014

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Center for Materials at Irradiation and Mechanical Extremes (CMIME); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1369955

Alternate Identifier(s):

OSTI ID: 1250968

Grant/Contract Number:  

2008LANL1026; AC52-06NA25396

Resource Type:

Accepted Manuscript

Journal Name:

Acta Materialia

Additional Journal Information:

Journal Volume: 84; Journal Issue: C; Related Information: CMIME partners with Los Alamos National Laboratory (lead); Carnegie Mellon University; University of Illinois, Urbana Champaign; Massachusetts Institute of Technology; University of Nebraska; Journal ID: ISSN 1359-6454

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Helium; Segregation; Dislocation mobility; Modeling; Monte Carlo