Dislocation structures in ni₃(si, ti) single crystals deformed on {001} slip

Abstract

The dislocation structures in Ni₃(Si, Ti) single crystals with L1₂ structure were investigated by means of transmission electron microscopy strong and weak-beam method combined with the tilting experiment, in the temperature regime where the deformation was performed on primary cube (001) slip. At 723 K, the [10] edge dislocations were dominated in the form of single superdislocations and also of dipole superdislocations, suggesting the dissociations into non-planar locked structures such as double-Lomer and super-Lomer configurations. At both temperatures of 798 K and 873 K, both edge and screw [10] dislocations were dominated in the forms of the looped configurations. It was suggested that the edge dislocations were locked by dissociating into double- or super-Lomer configurations while the screw dislocations were locked by the Kear-Wilsdorf configurations. At 1073 K, the mixture [10] dislocations were dominated, accompanied with a number of nodes of multiple slips. Also, the antiphase boundary energy on {001} plane was estimated by measuring the apparent width between two of the [10] superpartials. The APB energy changed from 124mJm⁻² to 77mJm⁻² with increasing temperature from 723 K to 1073 K.