THE MAGNETIC TRANSITION DUE TO PLASTIC-DEFORMATION IN NI75+XAL25-X AND NI77-XAL23PDX COMPOUNDS

The influence of plastic deformation on magnetic properties has been studied in Ni75+xAl25-x (0 less-than-or-equal-to x less-than-or-equal-to 2) and Ni77-xAl23Pdx (0 less-than-or-equal-to x less-than-or-equal-to 3) intermetallic compounds. The temperature dependence of the spontaneous magnetization, M(s)(T), has been analysed according to the self-consistent renormalization (SCR) theory of spin fluctuation. The qualitative agreement between the experimental result and the theoretical one is satisfactory in the plastically deformed samples. The value of M(s)(0) decreases slightly on compression; the reduction of M(s)(0) attains to 10% in the samples of 20% strain. However, the Curie temperature is constant within experimental error. The SCR theory indicates that plastic deformation gives an influence especially to the derivative of the density of states at the Fermi level. The dislocation distribution is observed under the electron microscope and its density, rho, is obtained for several samples. The relationship between M(s)(0) and rho suggests that the non-magnetic region spreads around the APB and CSF ribbons at least as far as 100 atomic distances, which are introduced between superpartial dislocations by plastic deformation.