Crystallization kinetics of Mg65Cu25Nd10 amorphous alloy

Autor: G.Y. Liang, Yong-Li Guo, D.C. Wu, Lu Li, L.J. Huang
Rok vydání: 2008
Předmět:
Zdroj: Journal of Non-Crystalline Solids. 354:1048-1053
ISSN: 0022-3093
DOI: 10.1016/j.jnoncrysol.2007.08.005
Popis: Amorphous Mg-based alloy Mg 65 Cu 25 Nd 10 was prepared by melt-spinning. The kinetics of crystallization of the alloy was investigated by DSC using various heating rates, and its crystallization process and microstructure were confirmed by TEM, X-ray and electron diffraction. The changeable activation enthalpy E a with crystalline fraction α was given by an isoconversional method, and the average value of E a was 150 ± 10 kJ/mol. What is more important, it is shown that this process cannot be described by the JMA model but the two-parameter empirical Sestak–Berggren equation gives a more quantitative description. It was established that the crystallization of Mg 65 Cu 25 Nd 10 alloy is a multi-step mechanism and can be described by the Sestak–Berggren model with the kinetic parameters as follows: m = 0.59, n = 1.42, A = 6.35 × 10 14 . It was found that the crystallization process of melt-spun Mg 65 Cu 25 Nd 10 ribbons consists of three steps. The first crystallization reaction at about 453 K is connected with the formation of Mg 2 Cu nanocrystalline phase, followed by formation of a coarser grained α-Mg crystalline phase (483–500 K) corresponding to a second crystallization reaction. At higher temperatures a third exothermic effect (at about 593 K) can be detected and the stable Mg 2 Cu, α-Mg and Cu 5 Nd phases are present.
Databáze: OpenAIRE
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