Intersection Faulting Mechanism Theory of Flow and Fracture of Face-Centered Cubic Metals

The intersection of any dislocation avalanche with a stationary dislocation having a Burgers vector component normal to the slip plane is shown to produce a close-packed partial plane of vacancies or interstitials in the slip plane, intrinsic or extrinsic faults for {111} slip planes. These faults have high energy in non-close-packed planes, consistent with observed slip plane preference. The mechanism gives improved understanding of recent x-ray results. Metallographic slip observations are consistent with the hypothesis that the etch indications are occurring at faults produced by the present mechanism. Fracture is postulated as resulting from the growth of "head-on" faults until transition occurs to the Griffith mechanism. Fault correction by partial slip produces additional dislocations, some potentially active as Frank-Read sources in the other slip planes. For copper, intrinsic or extrinsic faults are estimated to have energies of 40 ergs ${\mathrm{cm}}^{-2\mathrm{}}$ and maximum widths of 400 A.