Effect of Fe addition on the crystallization behaviour and Curie temperature of CoCrSiB-based amorphous alloys

Abstract

The crystallization behaviour and Curie temperature of melt-spun Co71-xFexCr7Si8B14 (x = 0, 2, 3.2, 4, 6, 8 and 12 at.%) amorphous alloys have been studied. Differential scanning calorimetry (DSC) showed two stages of crystallization. The first stage of crystallization (TX1) in the alloy with 6 at.% Fe was the highest and it had the highest activation energy. X-ray diffraction studies revealed that the primary crystalline phase is hcp-(CoCr)2Si for Fe-free alloy, whereas (CoFeCr)2Si and (CoFeCr)3Si phases were formed with the addition of Fe. hcp-Co was also formed along with these phases. The secondary crystalline phases were fcc-Co and various boron-rich phases. The Curie temperature of the alloys also changed with the addition of Fe to the system. Like the primary crystallization temperature, the Curie temperature of the alloys did not vary systematically with the Fe content. The addition of Fe to the Co-based system changes the nearest-neighbour interaction. This changes the exchange interaction between the transition metal elements. Due to the asymmetry in the Bethe-Slater curve, a systematic variation with Fe addition was not observed in the Curie temperature measurement.