REDUCING THE MAGNETIC LOSSES OF AMORPHOUS RIBBON

Amorphous alloys have lower magnetization losses than silicon steel an d are therefore used as the cores of high-efficiency electrical transf ormers. Laser scribing the amorphous alloys using a very low power, so as not to melt the surface, results in an appreciable decrease in cor e loss with no decrease in measurable induction. A 2-5 mm line spacing appears optimum. Scribing prior to or after magnetic annealing result s in similar properties, although the former requires a slightly highe r 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 mu m thick ribbon, a 29% decrease in core loss is obtained with no increas e in exciting power. For thick, 50 mu m ribbon, properties superior to those of conventional 25 mu m ribbon are achievable, the core loss be ing decreased nearly 50% with no increase in exciting power. Thick rib bon with these properties could decrease the fabrication cost, while i ncreasing the efficiency of power transformers. (C) 1998 Elsevier Scie nce S.A.