A Numerical Analysis of Deformation Processes in Oxide Dispersion-Strengthened Materials - Influence of Dislocation-Particle Interactions

Abstract:

A recently developed 3D discrete dislocation dynamics (DDD) model is employed to study kinetics of dislocation ensembles subjected to high temperature creep in microstructures of metal matrix composites. We particularly focus on a migration of low angle tilt boundaries in a field of rigid impenetrable particles. This type of dislocation boundaries represents a typical microstructural feature mediating plastic deformation during the high temperature loadings. The article compares results of numerical studies that considered distinct dislocation-particle in-teractions in order to describe the response of dislocation structure to the applied stress. The resultssuggest that, regardless the details related to the dislocation-particle interactions, a critical applied stress always exists, below which the boundary migration process ceases [1,2]. The existence of crit-ical threshold is confirmed by creep tests of ODS materials. This critical threshold, contrary to theclassical Orowan stress, is proportional to the dislocation density. The displacements of individual dislocation segments on the micro-scale level reflect the changes in the dislocation-particle interactions quite sensitively. Atthemacro-scale level, the overall strain rate, which averages out velocities of all the individual dislocation segments, is also significantly influenced by the changes in dislocation-particle interaction

• Periodical: Solid State Phenomena (Volume 258)
• Pages: 106-109
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.258.106
• Online since: December 2016
• Authors: Tomáš Záležák*, Filip Šiška, Luděk Stratil, Natália Luptáková, Miroslav Šmíd, Denisa Bártková, Jiří Svoboda, Antonín Dlouhý
• Keywords: 3D Discrete Dislocation Dynamics, High Temperature Creep, Metal Matrix Composites, Precipitate Hardening

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