Papers by Keyword: Crystallographic Slip

Abstract: We investigated the process of laser heat treatment of polished brass samples (36% zinc, containing a small amount of lead, which does not dissolve in the alloy and is in the form of inclusions, having micron and submicron size) by impacting to a series of 25 - 30 ultraviolet (UV) pulses of a Nd:YAG laser (third harmonic, wavelength λ = 355 nm, duration τ = 10 ns, pulse repetition rate f = 10 Hz, pulse energy density ~ 0.15 - 1.0 J/cm²) in the stationary spot mode. Copper and its alloys absorb up to 90% of the energy of this laser. It is found that the relaxation of the absorbed energy of laser radiation in the metal occurs nonuniformly. Defects in the metal structure such as grain boundaries and lead inclusions are visualized. Traces of crystallographic sliding appear inside some grains. With an increase in the number of impacting impulses, accumulation of damage is observed. A further increase in the radiation energy density leads to an aggravation of the observed phenomena.

Abstract: A mathematical model of elementary crystallographic slip, limited by a closed piecewise-continuous dislocation loop is proposed. A study of the evolution of the first dislocation loop emitted by a dislocation source in copper is carried out. It has been shown that on the dislocation loop on screw orientation and orientations close to it, about half a free path length before the stopping point there arises a concavity, which grows in size up to the stopping of the dislocation loop. In the final configuration the radius of the dislocation loop on screw orientation is practically by an order of magnitude less than the radius on edge orientation.