Non-isothermal Crystallization Kinetics of Co_(67)Fe_4Cr_7Si_8B_(14) Amorphous Alloy

摘要

Non-isothermal crystallization kinetics of Co_(67)Fe_4Cr_7Si_8B_(14) amorphous ribbons was studied by differential scanning calorimetry (DSC) technique under 10, 20, 30, 40 and 80 ℃min~(-1) heating rates. It is found that Co_(67)Fe_4Cr_7Si_8B_(14) amorphous alloy exhibits two-stage crystallization on heating. The two crystallization peaks shift to higher temperatures with increasing heating rate. The apparent activation energies (Ec) for the first stage of crystallization were determined as 443.44 and 434.47 kJmol~(-1) by using the Kissinger and Ozawa equations, respectively. Frequency factor (A) estimated to be 1.084 × 10~(26) s~(-1) using Kissinger equation. Kinetics parameters such as Crystallization exponent (n) and dimensionality of growth (N_(dim)) were determined using JMA (Johnson-Mehl-Avrami) method. Details of the nucleation and growth behaviours during the non-isothermal crystallization were studied in terms of local activation energy Ec(x) by the OFW (Ozawa, Flynn and Wall) method. Also the activation energy for nucleation (E_n) and growth (E_g) separately estimated.