Transmission electron microscopy study of plastic deformation in NiZr₂

Abstract

Plastic deformation mechanisms in the body centred tetragonal (C16-structure) NiZr₂ compound have been studied using transmission electron microscopy. Dislocations, stacking faults and microtwins have been characterized. Four families of dislocations have been identified: screw-type (b=[0 0 1]), edge-type ([0 0 1](1 1 0) and [110] (1¯10) systems) and mixed-type (1/2[1¯11] (110) system). Partial dislocations associated with stacking faults have also been detected and analysed. The plane of the faults is shown to be (1¯10) and the fault vectors 1/4 [1 1 1] and 1/4 [11¯1]. A hard-sphere model illustrating the formation mechanism of these stacking faults is proposed. The microtwins are found to be 60° rotation twins around the [1¯10]^* direction and can be described by the stacking faults scheme.