Ferromagnetic Anisotropy, Magnetization at Saturation, and Superstructure inNi3Fe and Nearby Compositions

The order-disorder transformation involving ${\mathrm{Ni}}_3$Fe affects both the ferromagnetic anisotropy and the saturation magnetization. Iron-nickel alloys in the range 65 to 80 percent nickel have been investigated, using spheroidal specimens. With superlattice formation the anisotropy becomes more like that of pure nickel with $〈111〉$ as the direction of easiest magnetization. The change is largest near ${\mathrm{Ni}}_3$Fe. The saturation magnetization increases with ordering; the greatest observed increase was 5.8 percent for an alloy very near ${\mathrm{Ni}}_3$Fe. Different rates of cooling from above the critical temperature (about 490°C) affect the saturation magnetization. These changes are attributed to changes in degree of local ordering effects. Long distance order, induced by baking for long periods, greatly influences both anisotropy and magnetization at saturation.