Nanocrystallization of metallic glasses

The paper summarizes briefly the current status of research in the field of nanocrystallization of metallic glasses especially highlighting the influe nce of glass composition and conditions of devitrification process on size, morphology and composition of crystallization products. Conventional cryst allization creates a nanocrystalline structure only in glasses with particu lar compositions. Any metallic glass, decomposing in a primary crystallizat ion process, can be converted into partially nano crystalline material usin g non-conventional methods of heat treatment, e.g. high-temperature or low- temperature nanocrystallization. Temperature of devitrification process inf luences sizes and compositions of crystallization products for any volume f raction of crystalline phase. The change of crystallites sizes can change t heir morphologies. The change of a crystallite composition usually affects the lattice parameter but also can result in a change of crystallographic s tructure of the same phase or in formation of another phase. Composition of primary crystallites is dependent on temperature as well as on time of dev itrification process. The lower the annealing temperature and the shorter t he annealing time (smaller crystallites) the more the crystallites composit ion differs from the equilibrium state. (C) 2001 Elsevier Science B.V. All rights reserved.