Metallurgy and Magnetic Properties Control in Permalloy

Abstract

The increasingly broad range of applications for the Permalloy family of magnetic materials has made them the object of intense and continuing study over the years. In this review, four main types of magnetic anisotropy are first discussed. These are the magnetocrystalline, magnetostrictive, thermomagnetic, and slip-induced anisotropies. It is pointed out that control of these anisotropies through composition selection and judicious processing procedures is the key to attainment of high initial permeability and squareness in the Ni–Fe–Mo–Cu system. Specifically, while zero anisotropy from all sources is the goal for high initial permeability, introduction of a nonzero anisotropy has proven effective in obtaining good squareness. The influence of metallurgical factors, in particular the role of crystallographic texture, is discussed.