Initiation of the Explosive Crystallization Process in Amorphous Alloys of the Fe-Zr System by Pulse Laser Treatment

In the work, a series of theoretical calculations were carried out to analyze the possibility of the process of explosive crystallization during laser treatment of binary amorphous alloys of the Fe-Zr system. The calculations were carried out within the framework of the modified theory of homogeneous crystallization for binary alloys, which takes into account the work associated with the concentration fluctuation. Calculation of the characteristics of the crystallization process was performed for two modes: slow heating at a speed of 0.16 K/s and an instant laser pulse, while it was considered that the amorphous tape was heated by a laser beam to a certain temperature within 10 – 6 seconds. The integral curve of the temperature dependence of the volume part of the crystalline phase during slow isothermal annealings is characterized by the presence of a «shelf», which indicates the two-stage crystallization process. The temperature range of crystallization at slow heating (0.16 K/s) is 90 K. We analyze the peculiarities of the crystallization process of amorphous alloys under the influence of laser treatment. The high heating rates, achieved by the laser treatment of amorphous alloys, create a number of differences in the course of crystallization processes compared with crystallization during slow isothermal annealings. According to the calculations, impulse heating to temperatures below 550 K does not cause crystallization. After 551 K, there are significant changes in the crystallization kinetics. At 552 K, the crystalline phase part has reached the value of 8 %. In the interval from 552 K to 553 K, there is a sharp jump in the value of the crystal phase proportion from 8 % to 99 %, that is a complete crystallization of the amorphous alloy occurs. The calculations carried out have shown that explosive crystallization may occur during the pulsed laser annealing of binary amorphous alloys of the Fe-Zr system. The temperature at which explosive crystallization is possible due to the laser pulse was less than 60 K for the temperature of the beginning of intensive crystallization at slow heating.