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Dissociation of Basal Dislocations in 4 H – SiC Single Crystals Deformed Around the Transition Temperature
Author(s) -
CastilloRodríguez Miguel,
Lara Ana,
Muñoz Antonio,
DomínguezRodríguez Arturo
Publication year - 2013
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12434
Subject(s) - nucleation , dissociation (chemistry) , crystallography , materials science , microstructure , dislocation , transmission electron microscopy , slip (aerodynamics) , atmospheric temperature range , activation energy , condensed matter physics , chemistry , chemical physics , nanotechnology , physics , thermodynamics , organic chemistry
The dislocation microstructure was studied in 4 H – SiC samples plastically deformed by basal slip activation around the transition temperature (1000°C–1100°C). Dissociation of basal dislocations takes place over a wide temperature range (800°C–1300°C), but its influence on dislocation motion is different in the high‐ and low‐temperature regimes due to the difference in mobility of partials. Consequently, this material exhibits a completely different mechanical behavior below and above its transition temperature, indicating a change in the deformation mechanism. In this work, the dislocation microstructure was studied around the transition temperature at which both mechanisms are still operative, thus providing a richer number of different configurations generated by dissociation of basal dislocations. They were observed and analyzed by means of the complementary use of weak‐beam dark‐field imaging and high‐resolution transmission electron microscopy. Firstly, 3C band nucleation in the 4 H – SiC matrix was identified and its appearance discussed from an energy standpoint. Secondly, the attractive interaction between partials in dipoles and the difference in mobility between the leading and the trailing partial have remarkable effects on the dissociation width, and explain the absence of work hardening above the transition temperature.