Plasticity of the Al$_{2}$Cu {\theta}-phase from ambient temperature to 300{\deg}C

The investigation of the deformation behaviour of intermetallic phases is mostly limited to high temperatures due to their low ductility at ambient temperature. Therefore, within this study, nanoindentation experiments on the Al$_{2}$Cu phase were performed from ambient temperature up to 300{\deg}C in conjunction with TEM investigations of the deformed material. It was found that the Al$_{2}$Cu phase starts to soften from temperatures above 150{\deg}C. The low temperature deformation behaviour was dominated by serrated yielding and transitioned towards a smooth deformation behaviour above 150{\deg}C. No slip traces were observed in the vicinity of the indents in both temperature regimes. The predominant dislocations observed after ambient temperature deformation and elevated temperature deformation are assumed to belong to the same operating slip systems. Therefore, the underlying deformation mechanism for both temperatures appears to be the same and thermally activated.