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

The dislocation structures in Ni3(Si,Ti) single crystals with Ll2 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 [110BAR] 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 [110BAR] 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 1073K, the mixture [11OBAR] 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 [110BAR] superpartials. The APB energy changed from 124 mJ m-2 to 77 mJ m-2 with increasing temperature from 723 K to 1073 K.