The interrelationship between microstructure, coercivity and magnetic viscosity in cobalt-aluminum and cobalt-nickel-aluminum fine-particle ferromagnets

In this investigation, Co-24.8 wt.% Al and Co-17.7 at.% Ni-26.8 at.% Al ;The as-quenched Co-Ni-Al alloy exhibits characteristic tweed contrast and diffuse ;The age hardening curve for the ternary alloy has been found to be similar to binary alloy; however, the temperature dependence of coercivity curve exhibits a flattening at elevated temperatures rather than an increase. Magnetic viscosity experiments were performed on the aged binary alloy with the results agreeing with the empirical Barbier plot of fundamental viscosity coefficient versus coercivity. Numerical analysis of the magnetic viscosity based on a modified Stoner-Wohlfarth coherent rotation mechanism using both the first and second magnetocrystalline anisotropy constants and the shape anisotropy constant was performed and the activation volume extracted.