Researches on the influence of the thermal treatment on the structure of the amorphous alloys

This paper presents the results of the researches carried out on the ribbons of amorphous alloys belonging to the Fe75-xCOxCr1B7Si17 system, where x = I, 4, 7 and 10 % at. The amorphous ribbons have been obtained by fast cooling of the melt on a rotary cylinder. By mean of the differential thermal analysis, the critical sounds of each alloy have been determined. The amorphous ribbons have been submitted to some thermal treatments at various temperatures (200, 250, 300, 350, 400, 450 degreesC) and exposure times (30, 60, 90 minutes). The sample surfaces have been studied before and after the thermal treatment. Because the thermal treatments have been performed within argon neutral atmosphere, no modifications have been noticed. The study by optical and electronical microscopy reveals the occurrence into the structure of certain crystals. The content of the new phase, FeB has been determined by X-ray diffraction. The effect of the temperature has been learnt by microhardness measurements. It decreases when increasing the thermal treatment temperature of the maintaining time. The variation of the amorphous alloy resistivity after the thermal treatment has been also studied. It can be concluded that the resistivity is a measure of the amorphous alloy crystallisation.