Reducing the magnetic losses of amorphous ribbon

Abstract

Amorphous alloys have lower magnetization losses than silicon steel and are therefore used as the cores of high-efficiency electrical transformers. Laser scribing the amorphous alloys using a very low power, so as not to melt the surface, results in an appreciable decrease in core loss with no decrease in measurable induction. A 2–5 mm line spacing appears optimum. Scribing prior to or after magnetic annealing results in similar properties, although the former requires a slightly higher laser power. Excimer and YAG lasers using optimized parameters both result in identical magnetic properties, but the optimum morphology of the scribed line is different for the two types of laser. For 25 μm thick ribbon, a 29% decrease in core loss is obtained with no increase in exciting power. For thick, 50 μm ribbon, properties superior to those of conventional 25 μm ribbon are achievable, the core loss being decreased nearly 50% with no increase in exciting power. Thick ribbon with these properties could decrease the fabrication cost, while increasing the efficiency of power transformers.