Thermal, Magnetic, and Structural Characterization of the Crystallization Kinetics of Amorphous Soft Magnetic Materials

Introduction An understanding of the crystallization kinetics of magnetic amorphous alloys is of scientific interest for two important reasons. First, for an alloy that exhibits excellent magnetic properties in its amorphous phase, the crystallization kinetics represent the limit at which these properties begin to deteriorate. Therefore, thermal stability determines the magnetic stability of the amorphous phase of the material. Second, for an alloy that exhibits excellent magnetic properties in its two-phase, nanocrystal-amorphous matrix structure, control over the crystallization kinetics provides the ability to tailor microstructure. The amount of nanocrystals formed within the matrix can be controlled to achieve the desired magnetic performance. The modes of crystallization — from the metastable amorphous state to the stable crystalline state — depend on various parameters, such as composition, concentration of nucleation sites, diffusion coefficients, activation energy for diffusion, free energy difference between amorphous and crystalline phases, and thermal history of the sample.