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Walter, C.; Wheeler, J. M.; Barnard, J. S.; Raghavan, R.; Korte-Kerzel, S.; Gille, Peter; Michler, J.; Clegg, W. J. (2013): Anomalous yielding in the complex metallic alloy Al13Co4. In: Acta Materialia, Vol. 61, No. 19: pp. 7189-7196


The single crystal deformation behaviour of orthorhombic Al13Co4 hasbeen studied below the brittle-ductile transition temperature observedin bulk material from room temperature to 600 degrees C, usingindentation, microcompression and transmission electron microscopy. Atroom temperature, slip occurred most easily by dislocation motion on the(0 0 1)[0 1 0] slip system, as observed in the ductile regime at hightemperatures. However, as the temperature was increased towards 600degrees C, the slip pattern changed to one consisting of linear defectsrunning perpendicular to the loading axis. Serrated flow was observed atall temperatures, although at 600 degrees C the magnitude of theserrations decreased. Anomalous yielding behaviour was also observedabove 226 degrees C, where both the yield and the 2\% flow stressincreased with temperature, almost doubling between 226 and 600 degreesC. It has been suggested that this might arise due to the increasingstability of orthorhombic Al13Co4 with respect to the monoclinic formwith increasing temperature. This is shown to be consistent with thetheoretical predictions that exist.