Studies of nanocrystalline phase and residual amorphous phase of FeCuNbSiB alloy

The σ-T and dσ/dT-T curves of the FeCuNbSiB amorphous alloy, which are the relationship between "apparent weight loss" and temperature, are investigated by magnetic thermogravimetry analysis (MTGA) technique. It is found that the crystallization process of the samples can be divided into five stages. The studies of samples annealed in the temperature range of 480-610 °C for 1 h show that when the annealing temperature (Ta) is lower than 540 °C, the quantity of nanocrystalline α-Fe(Si) phase increases evidently with Ta, and the Curie temperature (TC) of residual amorphous phase also increases linearly with Ta, i.e., TC=0.52Ta+91.7 °C, with correlation coefficient γ=0.98. The variation of volume fraction of α-Fe(Si) nanocrystalline phase or residual amorphous phase with Ta is measured.