Morphological and Structural Study of Heat-Affected Zone Induced by Laser Cutting of Glassy Metal Tapes

The promising properties of glassy alloys are the low coercive force and the low core loss. Although, the Fe-based amorphous ribbons are excellent in this respect, several additional requirements have to be satisfied, like the shaping of this soft magnetic tapes into the appropriate forms, and simultaneously avoiding the degradation (local crystallization) of the individual glassy elements. In this article the results of laser cutting experiments is reported. This cutting process causes local degradation, which is known as the "heat affected layer". This layer appears as a visible parallel zone with the cutting front in the micrograph. The thickness of this front depends on several parameters of cutting procedure (power density of beam and scanning rate or the flow rate of applied working gas). In this paper the fine structure of the heat affected zone is investigated. The high resolution pictures shows a columnar microstructure of the heat affected layer, resembling a typical re-solidified microstructure. The dimension of columnar structure changes drastically according to the requirements of unidirectional heat conduction. The magnitude of heat affected zone will be correlated with the soft magnetic properties of the samples.