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

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Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Materials at Irradiation and Mechanical Extremes (CMIME)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Acta Materialia; Journal Volume: 84; 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
Country of Publication:
United States

Citation Formats

Martínez, Enrique, Schwen, Daniel, and Caro, Alfredo. Helium segregation to screw and edge dislocations in α -iron and their yield strength. United States: N. p., 2015. Web. doi:10.1016/j.actamat.2014.10.066.
Martínez, Enrique, Schwen, Daniel, & Caro, Alfredo. Helium segregation to screw and edge dislocations in α -iron and their yield strength. United States. doi:10.1016/j.actamat.2014.10.066.
Martínez, Enrique, Schwen, Daniel, and Caro, Alfredo. 2015. "Helium segregation to screw and edge dislocations in α -iron and their yield strength". United States. doi:10.1016/j.actamat.2014.10.066.
title = {Helium segregation to screw and edge dislocations in α -iron and their yield strength},
author = {Martínez, Enrique and Schwen, Daniel and Caro, Alfredo},
abstractNote = {},
doi = {10.1016/j.actamat.2014.10.066},
journal = {Acta Materialia},
number = ,
volume = 84,
place = {United States},
year = 2015,
month = 2
  • The interactions of He and vacancy defects with <111> screw dislocations in alpha-Fe are modeled using molecular statics, molecular dynamics and transition state energy determinations. The formation energies and binding energies of interstitial He atoms, vacancies and He-vacancy clusters near and within dislocations in alpha-Fe are determined at various locations relative to the dislocation core. Using the dimer transition state method the migration energies and trajectories of the He and vacancy defects near and within the screw dislocation are also determined. Both interstitial He atoms and single vacancies are attracted to and trapped in the dislocation core region, and theymore » both migrate along the dislocation line with a migration energy of about 0.4 eV, which is about half the migration energy of vacancies in the perfect crystal and about five times the migration energy for interstitial He in the perfect crystal. Divacancies and He-divacancy complexes have migration properties within the dislocation core that are similar to those in the perfect crystal, although the stability of these defects within the dislocation may be somewhat less than in the perfect crystal.« less
  • Flat Cd single crystals were grown having crystallographic orientations which permitted that, at least during the first stages, plastic deformation was controlled by dislocations of predominately edge or screw character. The temperature dependences of flow stress, activation volumes, and activation enthalpies were determined. (DLC)
  • Using multi-ion interatomic potentials derived from first-principles generalized pseudopotential theory, we have studied ideal shear strength, point defects, and screw dislocations in the prototype bcc transition metal molybdenum (Mo). Many-body angular forces, which are important to the structural and mechanical properties of such central transition metals with partially filled {ital d} bands, are accounted for in the present theory through explicit three- and four-ion potentials. For the ideal shear strength of Mo, our computed results agree well with those predicted by full electronic-structure calculations. For point defects in Mo, our calculated vacancy-formation and activation energies are in excellent agreement withmore » experimental results. The energetics of six self-interstitial configurations have also been investigated. The {l_angle}110{r_angle} split dumbbell interstitial is found to have the lowest formation energy, in agreement with the configuration found by x-ray diffuse scattering measurements. In ascending order, the sequence of energetically stable interstitials is predicted to be {l_angle}110{r_angle} split dumbbell, crowdion, {l_angle}111{r_angle} split dumbbell, tetrahedral site, {l_angle}001{r_angle} split dumbbell, and octahedral site. In addition, the migration paths for the {l_angle}110{r_angle} dumbbell self-interstitial have been studied. The migration energies are found to be 3{endash}15 times higher than previous theoretical estimates obtained using simple radial-force Finnis-Sinclair potentials. Finally, the atomic structure and energetics of {l_angle}111{r_angle} screw dislocations in Mo have been investigated. We have found that the so-called {open_quote}{open_quote}easy{close_quote}{close_quote} core configuration has a lower formation energy than the {open_quote}{open_quote}hard{close_quote}{close_quote} one, consistent with previous theoretical studies. (Abstract Truncated)« less