Our study of the properties of nickel-titanium alloys subjected to external exposure provides a new insight into the origin of the magnetization effect emerging in these alloys. It is shown to be associated with the nonzero magnetic moments of cluster structures formed under these conditions. The calculated mass magnetization agrees well with the experimental one. All calculations are carried out in the framework of the density functional theory (DFT/PBE and DFT/PZ) using plane wave basis sets and additionally verified by the multiple scattering method.