Thermal stability and crystallization process in a Fe-based bulk amorphous alloy: The kinetic analysis

In this work, the thermal stability and non-isothermal kinetic analysis of crystallization process in (Fe41Co7Cr15Mo14Y2C15)94B6 amorphous alloy were investigated. The research findings revealed that crystallization process was done in four stages whereby the crystalline phases including Fe23 (B, C)6, Fe3Mo3C, and Mo3Co3C were formed. In order to determine the activation energy of every crystallization stages, the isoconversional methods were used. The activation energies were calculated about 550, 620, 550, and 820 kJ/mol for I, II, III, and IV crystallization stages, respectively. Also, values of the rate constant at the peak temperature of crystallization, Kp; Avrami exponent, n; and growth dimensional, m; were determined by means of Augis-Bennett and Gao-Wang methods. Furthermore, for a more accurate determination of kinetic parameters including n, and m, these kinetic parameters were obtained by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) and Matusita. The values of m were calculated equal to 2, 1, 2, and 3 for I, II, III, IV crystallization stages, respectively. Also, the obtained nucleation index, showed that the rate of nucleation in I, II, and III crystallization stages were zero. Therefore, it can be acceptable that a large number of nuclei related to these stages already exist in the specimen.