Specific features of deformation of Ni–Fе–Ga–Co single crystals grown from melt by the Stepanov method

The influence of thermomechanical cycles (compression along the [011] direction and recovery of the shape memory strain upon crystal heating) on the form and characteristics of the compression diagrams of Ni$_{49}$Fe$_{18}$Ga$_{27}$Co$_{6}$ alloy crystals not subjected to high-temperature annealing and quenching in water after the growth has been investigated. It is found that these characteristics change during the first nine cycles. Starting from the tenth thermomechanical cycle, they become stable and the deformation properties of the crystals become similar to those of quenched crystals of this alloy. This means that antiphase nanodomains are dispersed by dislocations during the thermomechanical cycling, as a result of which the disordered $B_2$ crystal structure is transformed into the ordered $L2_1$ structure, which is characteristic of quenched crystals.