Abstract
Strengthening mechanisms of Ni3Ge single crystals have been studied by compression tests below and above the peak temperature where the anomalous strengthening due to octahedral slip involving cube cross-slip changes to primary cube slip. From the three-dimensional analysis of the dislocation structure after deformation, it is revealed that the superdislocations take various configurations depending on the test temperature and the starting dislocation structure introduced by pre-straining at different temperatures. It is also confirmed that the anomalous strengthening appears in a wide temperature range by octahedral slips for the [001] compression. Based on these observations, origin of the striking strengthening in Ni3Ge is attributed to the cube cross-slip and the resultant complex dislocation structure below the peak temperature, and the primary cube slip involving dislocation climb above it.