Thermal analysis of directional pressure annealed Fe78Si9B13 amorphous ribbons

The structure, magnetic properties and non-isothermal crystallization behavior of widthwise/lengthwise pressed and annealed (WPA and LPA), solely annealed (ANN) and as-quenched (AQ) Fe78Si9B13 amorphous ribbons were investigated. The first crystallization process of samples fits Johnson-Mehl-Avrami (JMA) model and then follows the Normal-Grain-Growth (NGG) model. Annealing treatment decreases the crystallization activation energy Ec; while WPA and LPA samples have a lower magnetic lose, larger nucleation and growth activation energies En and Eg than ANN sample, indicating that the pressure suppresses the crystallization and reduces free volume and forms the ordered clusters with a different structure of α-Fe(Si) during annealing process. In addition, the widthwise pressed treatment reduces free volume and suppresses crystallization in a larger degree than the lengthwise pressed treatment.