LOW CORE LOSS OF A BCC FE86ZR7B6CU1 ALLOY WITH NANOSCALE GRAIN-SIZE

We have investigated the possible applications potential of a newly developed bcc-nanocrystalline Fe86Zr7B6Cu1 alloy by determining the core loss, permeability mu-e, and magnetization B800 (at a field 800 kA/m). The above parameters have been studied as a function of annealing temperature T(a) of the as-quenched amorphous alloy, maximum induction B(m), and frequency (up to 100 kHz). On transformation to the bcc-nanocrystalline state at 873 K with a 10 nm grain size, maximum values of mu-e = 41000 and B800 = 1.52 T are obtained. The determined core loss is found to achieve a minimum value of 66 mW/kg at 1 T, 50 Hz. This value is considerably smaller (45 and 95% respectively) than those reported for the amorphous Fe78Si9B13 and bcc Fe-3.5%Si alloys now in use as transformer core materials. The observed B(m) and frequency dependences of the loss values for our new Fe-Zr-B-Cu alloy are consistently found to be superior as well. Thus, the bcc-nanocrystalline Fe-Zr-B-Cu alloy is quite promising for practical use as a core material in various transformers with the advantage of high B800, high mu-e and low core loss.