Joining of Fe-Base Amorphous Alloy Ribbons Using High-Voltage Discharging

Amorphous Fe78Si9B13 alloy ribbons were joined by high voltage discharging at various pressures and input energies. The joined alloy ribbons have a high relative density of 93 to 98%. The interface among ribbons is melted partially by discharging , where we can confirm a halo pattern without any contrast revealing the existence of a crystalline phase by a transmission electron microscope observation prepared at the input energy of 0.6 kJ·g−1. Furthermore, the tensile fracture surface of the melted region has a vein pattern resulting from the final fracture process in amorphous structure, which is represented that even the melted part has an amorphous structure by requenching. The structure of the melted region changes to the crystalline phase with the increase of input energy. The halo pattern disappears in the melted region prepared at the input energy of 2.0 kJ·g−1 and the tensile fracture surface shows a shell pattern revealing the embrittlement by the crystallization. The crystallization process proceeds through a metastable phase which is a mixture of MS-I and MS-II phases above the input energy of 1.5 kJ·g−1. These two metastable phases are corresponding to a bcc structure and a complex ordered structure containing a large amount of metalloids. The DC soft magnetic properties and core loss at 60 Hz deteriorate drastically with the increase of input energy above 1.5 kJ·g−1, which is mainly due to the increase of hysteresis loss by joining of high voltage discharging under the applied pressure.