Assessment of strain hardening in copper single crystals using in situ SEM microshear experiments
| Autor: | Guillaume Laplanche, A.B. Parsa, J.-K. Heyer, Janine Pfetzing-Micklich, Gunther Eggeler, N. Wieczorek |
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| Rok vydání: | 2016 |
| Předmět: |
Miniature tensile and microshear testing
Scatter Materials science Polymers and Plastics Scanning electron microscope 02 engineering and technology Plasticity 01 natural sciences In situ SEM 0103 physical sciences Ultimate tensile strength Composite material Strain hardening Sudden deformation events Tensile testing 010302 applied physics Lüders band Metals and Alloys Cu single crystals Strain hardening exponent 021001 nanoscience & nanotechnology Electronic Optical and Magnetic Materials Crystallography Ceramics and Composites Dislocation Deformation (engineering) 0210 nano-technology |
| Zdroj: | Acta Materialia. 113:320-334 |
| ISSN: | 1359-6454 |
| DOI: | 10.1016/j.actamat.2016.04.055 |
| Popis: | The effect of a pre-strain on the plasticity of copper single crystals subjected to in situ microshear deformation in a scanning electron microscope (SEM) is investigated. Pre-strains of 6.5 and 20% are imposed using [1 0 0] tensile testing. During tensile pre-deformation, several slip systems are activated and irregularly spaced slip bands form. A trace analysis revealed the presence of several slip bands on the tensile specimen near the grips while one family of slip bands parallel to the (1 1 1) crystallographic plane were detected in the middle of the tensile specimen. From the middle of the pre-deformed tensile specimens double microshear samples were prepared using focused ion beam (FIB) machining such that the [0 -1 -1] (1 -1 1) slip system could be directly activated. The results show how microshear behavior reacts to different levels of tensile pre-deformation. Sudden deformation events (SDEs) are observed during microshear testing. The critical stress associated with the first SDE is shown to increase with increasing pre-deformation as a result of an increasing number of slip bands introduced during pre-deformation per shear zone. The results allow also to obtain information on the interaction between dislocations activated during microshearing ([0 -1 -1] (1 -1 1)) and those which were introduced during tensile pre-deformation ([1 0 -1] (1 1 1) and [1 -1 0] (1 1 1)). When these slip systems interact glissile junctions and Lomer-Cottrell locks are likely to form. In the light of this analysis, we rationalize the occurrence of sudden deformation events based on piled up dislocation assemblies which overcome Lomer-Cottrell lock barriers. |
| Databáze: | OpenAIRE |
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