Magnetic hardening and phase segregation in CuNiFe and CuNiCo alloys

The temperature dependence of the coercive fields in aged CuNiFe and CuNiCo has been measured between 300 K and 77 K. The results are interpreted in terms of shape anisotropy of the ferromagnetic phase of the alloys and the variation of ferromagnetic particle volume with ageing time is deduced from the results. An arrest of the volume increase with ageing time is attributed to the start of coherency loss between the ferromagnetic and paramagnetic phases of the alloy when the diameter of each lamellar interface is about 600 Å.