Simulation of alnico coercivity

TL;DR

This paper uses micromagnetic simulations to analyze the coercivity of alnico, revealing how microstructure and interactions influence magnetic properties, with results aligning well with experimental data.

Contribution

It demonstrates the impact of microstructural features and interactions on alnico coercivity through detailed simulations, highlighting factors that can be optimized via processing.

Findings

Coercivity deviates from Stoner-Wohlfarth predictions due to microstructure.

Single-rod effects and interactions limit maximum coercivity.

Simulation results agree with recent experimental observations.

Abstract

Micromagnetic simulations of alnico show substantial deviations from Stoner-Wohlfarth behavior due to the unique size and spatial distribution of the rod-like Fe-Co phase formed during spinodal decomposition in an external magnetic field. The maximum coercivity is limited by single-rod effects, especially deviations from ellipsoidal shape, and by interactions between the rods. Both the exchange interaction between connected rods and magnetostatic interaction between rods are considered, and the results of our calculations show good agreement with recent experiments. Unlike systems dominated by magnetocrystalline anisotropy, coercivity in alnico is highly dependent on size, shape, and geometric distribution of the Fe-Co phase, all factors that can be tuned with appropriate chemistry and thermal-magnetic annealing.