The subject of research in this work is the deformation effects of aged Cu–Al–Mn alloys. According to the data of uniaxial tension tests, the phase equilibrium diagrams of austenite and martensite phases are constructed. The deformation behaviour under the action of temperature and mechanical stresses is estimated, the values of critical strain for the formation of strain-induced martensite are obtained, and the factors having an effect on the degree of superelastic recovery are elucidated. The linear thermal expansion coefficients of high- and low-temperature phases and the magnitude of volume effect of martensitic transformation are determined from the change in the linear dimensions of the samples. Magnetic properties of the alloys and the parameters affecting them are investigated. According to the data of magnetic analysis, the calculations of both magnetic parameters of the alloys and size effects of particles, which determine the induced deformation effects under the influence of temperature and mechanical stress, is made.