Edge dislocation-circular inclusion interactions at elevated temperatures

• Published in: Acta metallurgica 1983-12, Vol.31 (12), p.2151-2159
• Main Authors: Srolovitz, D.J., Petkovic-Luton, R.A., Luton, M.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Creep; Defects and impurities in crystals; microstructure; Dispersion hardening metals; Exact sciences and technology; Mechanical and acoustical properties of condensed matter; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Physics; Powder metallurgy. Composite materials; Production techniques; Structure of solids and liquids; crystallography
• ISSN: 0001-6160
• DOI: 10.1016/0001-6160(83)90034-2

While previous analyses of dislocation-inclusion interactions during the creep of dispersion strengthened systems have generally concluded that the dislocation climbs over the inclusion, detailed consideration of the associated elastic and diffusive problems, analyzed here, indicate that climb by-pass of the inclusion is not possible. In order to keep the elastic problem tractable, we consider a straight edge dislocation interacting with a cylindrical inclusion of infinite extent. Additionally, since we are concerned with interactions at elevated temperatures, we allow the matrix-inclusion interface to slip. We find that along approximately 1 2 of the glide planes intersecting the inclusion, the dislocation is attracted toward the inclusion. Dislocations originally lying on those glide planes, where the dislocation-inclusion interaction is repulsive, respond by either climbing on to a glide plane where the interaction is attractive or by diffusionally relaxing the repulsion. Therefore, a dislocation that is gliding on my plane that intersects the inclusion will end its trajectory at the inclusion-matrix interface. When the dislocation-inclusion separation is of order a dislocation core diameter, the dislocation core relaxes into the inclusion-matrix interface, thereby pinning the dislocation. Unpinning the dislocation requires a stress of order the Orowan stress, which is believed to give rise to the observed threshold stress for creep in dispersion strengthened systems. Alors que les analyses antérieures des interactions entre dislocations et inclusions au cours du fluage de systèmes durcis par une phase dispersée ont généralement conclu que la dislocation franchit l'inclusion par montée, l'étude détaillée des problèmes associés d'interaction élastique et de diffusion ont montré que ce franchissement de l'inclusion par montée n'était pas possible. Pour que le problème d'élasticité soit soluble, nous avons considéré l'interaction d'une dislocation coin rectiligne avec une inclusion cylindrique infinie. De plus, puisque nous étudiions les interactions à haute température, nous avons autorisé le glissement de l'interface matrice/inclusion. Nous avons trouvé que, suivant la moitié environ des plans de glissement coupant l'inclusion, la dislocation était attirée vers l'inclusion. Les dislocations situées initialement dans les plans de glissement oú l'interaction dislocation-inclusion est répulsive, réagissent soit en montant dans un plan de glissement oú l'int