Crystal Magnetic Anisotropy Constant and Magnetostriction Dependences of the High Magnetic Permeability for “Nimalloy” in the Ni-Mn System

Crystal magnetic anisotropy constant K1 and saturation magnetostriction λs have been measured on the (100) single crystal disk and polycrystal rods of Ni-Mn alloys containing less than about 25%Mn which were heat treated in different ways. The negative values of K1 and λs decreased rapidly with increasing Mn content and changed the sign from minus to plus at about 20%Mn. At compositions lower than about 20%Mn, both values remained almost unchanged with heat treatments. From these results, it may be concluded that the high permeability of Ni-Mn alloys containing about 20%Mn is caused by the very small values of K1 and λs.