Saenko G. Phase formation processes in binary and multicomponent amorphous alloys and their effect on thermal stability.

It is theoretically and experimentally proven that the crystallization process of the Fe-B basic binary alloys passes several phases in correspondence with their state diagram: first, a solid solution of boron in α-iron (β-phase) crystallizes with the boron concentration in amorphous matrix growing up; then at some point the crystallization of the Fe3B chemical compound begins ( γ-phases). It is shown that multicomponent amorphous alloys possess higher thermal stability compared to the binary allows because of the diffusion processes slowdown related to the formation of ultradispersive compounds delaying the diffusion processes of Fe and B, thus inhibiting the formation of the common phases of the basic alloy, which crystallize first. The process of purification of the amorphous matrix from frozen-in crystallization centers was theoretically grounded and implemented experimentally on the basis of analysis of the provisions of the thermodynamics theory of high-temperature stability of amorphous alloys, which claims existence of the temperature range, in which the chemical potential difference between phases in the heterogeneous system amorphous matrix - frozen-in centers is negative, thus complying with the condition for the possibility of dissolution of the frozen-in centers. It is demonstrated that the suggested thermal processing modes allow to extend the thermal stability ranges of the iron-based amorphous alloys by (20-40) K by means of purification of the amorphous matrix from the frozen-in crystallization centers by the ascending diffusion. On the basis of analysis of the theory of high-temperature thermodynamic stability of amorphous alloys, a new method of obtaining amorphous nanocrystalline state from the initially amorphous state was proposed.