Contribution of Defect Dragging to Dislocation Damping. I. Theory

Abstract

The contribution of dragging of point defects attached to dislocation lines, to dislocation damping, to elastic modulus, and to logarithmic decrement, is developed. It is shown that the dragging leads to an initial increase in decrement in a suitable frequency range, determined by other related parameters: dislocation loop length, line tension, and damping constants.The theory predicts a dependence on frequency of v, in contrast to the Koehler-Granato-Lucke (KGL) frequency dependence of cu, explaining the failure of previous experiments to confirm the KGL theory. In a similar manner, the generally accepted dependences on point-defect density are shown to be incorrect at lower frequencies, below a few kHz in copper. For example, it is shown that the dislocation decrement should be proportional to the two-thirds power of the modulus defect, rather than proportional to the square of the modulus defect as previously expected, at large point-defect densities on dislocation lines.

Mobility of Twin Boundaries in Fe-Pd-Based Ferromagnetic Shape Memory Alloys

“…A decrease in the amount of quenched-in-dislocations and vacancies to be dragged leads to a reduction in the values of martensitic damping controlled by dragging. 49,50) …”

Interaction entre dislocations et défauts ponctuels créés par bombardement électronique dans l'argent

“…Nous avons réalisé des expériences pour clarifier ce point particulier que nous présentons dans le paragraphe 3. 3. Dans la partie suivante (3.4), nous avons voulu déterminer si l'effet anormal de variation du frottement intérieur observé par Simpson et Sosin au cours d'une irradiation dans le cuivre [11] [3,12,13], et il n'a pas été observé dans celui de l'argent par Van Konynenburg [8] ; plusieurs théories tentent de l'expliquer ( [11,14,15] et Mercier à paraître), et nous désirons les tester dans l'argent. [Resonance frequency and internal friction for specimen El during an irradiation at 20 K.…”

Some memories of Kurt Lücke

“…Much of our work on the effects of thermal fluctuations on dislocation damping [11], and later on dislocation drag by impurities [12,13] was done during these visits. The dislocation drag effect provided a relaxation effect at low strain amplitudes which could explain effects found at frequencies as low as 1 Hz and peculiar reverse pinning effects discovered by Simpson and Sosin [14].…”