Accession Number:

ADA523964

Title:

Atomistic Simulations of Athermal Cross-Slip at Screw Dislocation Intersections in Face-Centered Cubic Nickel

Descriptive Note:

Journal article (preprint)

Corporate Author:

AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE

Report Date:

2010-01-01

Pagination or Media Count:

37.0

Abstract:

The Escaig model for thermally activated cross-slip in Face-Centered Cubic FCC materials assumes that cross-slip preferentially occurs at obstacles that produce large stress gradients on the Shockley partials of the screw dislocations. However, it is unclear as to the source, identity and concentration of such obstacles in single-phase FCC materials. In this manuscript, we describe embedded atom potential, molecular-statics simulations of screw character dislocation intersections with 120-deg forest dislocations in FCC Ni to illustrate a new mechanism for cross-slip nucleation. The simulations show how such intersections readily produce cross-slip nuclei and thus are preferential sites for spontaneous athermal cross-slip. The energies of the dislocation intersection cores are determined and it is shown that a partially cross-slipped configuration for the intersection is the most stable. In addition, simple 3-dimensional dislocation dynamics simulations accounting for Shockley partials are shown to qualitatively reproduce the atomistically-determined core structures for the same dislocation intersections.

Subject Categories:

  • Inorganic Chemistry
  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE