RAPID WORK-HARDENING CAUSED BY CUBE CROSS SLIP IN NI3AL SINGLE-CRYSTALS

Dislocation structures introduced by deformation at various temperatur es in the anomalous strengthening region in Ni3Al single crystals have been examined using high voltage electron microscopy with special car e in preserving the bulk structure after deformation. The three-dimens ional dislocation structures found by stereo microscopy have been anal ysed and correlated with the high-temperature strengthening. It is sho wn that the rapid work hardening leading to the anomalous strengthenin g is essentially controlled by the Kear-Wilsdorf locking or the (010) cross slip and is not affected by the secondary slip. The origin of th e transition in the strain-rate sensitivity has also been considered a nd is attributed to the transition in the hardening mechanism due to ( 010) cross slip.