Accession Number:

ADA566758

Title:

Activated States for Cross-slip at Screw Dislocation Intersections in Face-Centered Cubic Nickel and Copper via Atomistic Simulation

Descriptive Note:

Journal article

Corporate Author:

AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH

Personal Author(s):

• Rao, S. I.
• Dimiduk, D. M.
• El-Awady, J. A.
• Parthasarathy, T. A.
• Uchic, M. D.
• Woodward, C.

Report Date:

2010-01-01

Pagination or Media Count:

12.0

Abstract:

We extend our recent simulation studies where a screw dislocation in face-centered cubic fcc Ni was found to spontaneously attain a low energy partially cross-slipped configuration upon intersecting a forest dislocation. Using atomistic molecular statics simulations with embedded atom potentials, we evaluated the activation barrier for a dislocation to transform from fully residing on the glide plane to fully residing on a cross-slip plane intersecting a forest dislocation in both Ni and Cu. The activation energies were obtained by determining equilibrium configurations energies when variable pure tensile or compressive stresses were applied along the 1 1 1 direction on the partially cross-slipped state. We show that the activation energy is a factor of 2-5 lower than that for cross-slip in isolation via the Escaig process. The cross-slip activation energies obtained at the intersection in Cu were in reasonable accord with the experimentally determined cross-slip activation energy for Cu. Further, the activation barrier for cross-slip at these intersections was shown to be linearly proportional to db square root of lnsquare root of 3 db, as in the Escaig process, where d is the Shockley partial dislocation spacing and b is the Burgers vector of the screw dislocation. These results suggest that cross-slip should be preferentially observed at selected screw dislocation intersections in fcc materials.

Descriptors:

• *MOLECULAR DYNAMICS
• ACTIVATION ENERGY
• COPPER
• DISLOCATIONS
• NICKEL
• REPRINTS
• SIMULATION

Subject Categories:

• Properties of Metals and Alloys
• Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE