Cross-Slip Behaviour of Superlattice Dislocations in Ordered Ni3Fe

Plastic deformation of L1₂ ordered alloys proceeds by the glide of superlattice dislocations on {111} planes at room temperature. Since the antiphase boundary energy has its lowest value on {100} planes the cross-slip behaviour of superlattice dislocations on both {111} and {100} planes is studied in ordered Ni₃Fe. Single crystals of Ni₃Fe were deformed, afterwards ordered and additionally deformed at room temperature thus increasing the internal stresses. The dislocation structure is studied by transmission electron microscopy methods. The experimental results show that at room temperature cross slip of superlattice dislocations from {111} onto another {111} plane is rather frequent but very rare from {111} onto {100} planes. This result agrees with cross-slip models of dissociated dislocations and is confirmed by calculations of the core structure of superlattice dislocations recently published in the literature.