On recovery of dislocations in subgrains and subgrain coalescence
Abstract
A model is presented for the recovery of dislocations in the subgrain interiors and in the subboundaries. In addition to the pairwise annihilation the transfer of dislocations between the interior and the boundaries is considered. It is demonstrated that the recovery of the dislocations in the subgrain interiors in general occurs in two steps: first by pairwise annihilation and then by absorption at the boundaries, the latter process being essentially slower.
The contribution from two mechanisms for subgrain coalescence is derived: extraction and emission of dislocations from the subboundaries. These contributions are compared to that from migration of boundary dislocations derived by Li. A comparison is also made to the subgrain growth rate due to subboundary migration. The two latter contributions which both involve the collective migration of dislocations, and are therefore conveniently referred to as such, are identical up to a numerical factor and occur consequently always together. Comparison to experiments will be made in a forthcoming paper.
Résumé
On présente un modèle pour la restauration des dislocations à l'intérieur des sous-grains et aux sous-joints. En plus de l'annihilation par paires, on considère également le transfert de dislocations entre l'intérieur et les joints. On démontre que la restauration des dislocations à l'intérieur des sousgrains se produit en deux étapes: d'abord l'annihilation par paires, puis l'absorption par les joints, ce dernier processus étant plus lent.
On obtient la contribution de deux mécanismes à la coalescence des sousgrains: l'absorption et l'émission de dislocations par les sous-joints. On compare ces contributions à celle de la migration des dislocations de joints obtenue par Li. On les compare également à la vitesse de croissance des sous-grains due à la migration des sous-joints. Ces deux dénières contributions, qui mettent toutes deux en jeu la migration collective de dislocations sont identiques à un facteur numérique près et se produisent donc toujours ensemble.
Zusammenfassung
Es wird ein Modell für die Erholung von Versetzungen im Subkorninnenbereich und in Subkorngrenzen vorgelegt. Zusätzlich zu der paarweisen Annihilation wird der Austausch von Versetzungen zwischen dem Innenbereich und den Korngrenzen berücksichtigt. Es wird gezeigt, daβ die Versetzungserholung im Subkorninnenbereich im allgemeinen in zwei Schritten abläuft: Zuerst durch paarweise Annihilation und dann durch Absorption an den Korngrenzen, wobei der letztere Prozess wesentlich langsamer abläuft.
Der Beitrag zweier Mechanismen des Zusammenwachsens von Subkörnern wird abgeleitet: Extraktion und Emission von Versetzungen aus den Subkorngrenzen. Diese Beiträge werden mit denjenigen der Wanderung von Korngrenzversetzungen, hergeleitet von Li, verglichen. Ebenso wird die Wachstumsgeschwindigkeit der Subkörner durch Subkorngrenzwanderung verglichen. Die beiden letzteren Beiträge, die beide kollektive Wanderung von Versetzungen bedeuten und daher zweckmäβigerweise auch so bezeichnet werden, sind bis auf einen numerischen Faktor identisch und laufen folglich immer gleichzeitig ab.
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