Interfacial and Junction Line Defect Analysis for Plasticity Investigations

Abstract

Line defects at interfaces and interface junctions influence the plastic behaviour of polycrystals through their gliding motion and their interactions with other microstructural features. Appropriate characterisation techniques are important to assess such influences. The topological theory of line defects [1,2] provides valuable information towards this goal. We demonstate the use of topological methods in the study of plasticity micromechanisms through the analysis of two cases at mesoscopic level. The first concerns the interaction of gliding dislocations and interfaces in ordered alloys. These materials are promising for advanced applications due to their low weight and improved strength at high temperatures. However, a major problem is their propensity for intergranular fracture at ambient temperatures [3]. The second issue concerns the defect character of interface junction lines. In recent literature, junction line defects have been correlated with the plasticity of nanocrystalline materials and the onset of amorphisation by powder metallurgical methods [e.g. 4–6].