Influence of process parameters and alloy composition on structural, magnetic and electrical characteristics of Ni–Fe permalloys

Structural, magnetic and electrical studies have been carried out in three Ni–Fe based permalloys (82.13, 79.90 and 47.01% Ni) under hydrogen atmosphere by varying process parameters such as annealing temperature, cooling rate and holding time. These materials have been characterized for various magnetic properties such as remanence, coercivity, peak permeability and core loss under changed annealing profile conditions and correlated the results with XRD and microstructural observations. We found that grain diameter and ordering parameter have significant effect on the magnetic properties of the alloys. 82.13% Ni alloy is found to show better magnetic properties over the other two alloys as a function of different process parameters. We attribute it to relatively larger grain diameter and short-range order (SRO) developed in 82.13% Ni alloy over other two alloys. The alloys were tested for watch movement and audio head applications. We found that the battery life of the watch movement improved by 38% using 79.90% Ni alloy over 47.01% Ni alloy. Also, found that audio head performance is better with 82.13% Ni alloy as compared to 79.90% Ni alloy.