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摘要:
Erbium (Er) has attracted considerable attention as a substitute to scandium (Sc) for microalloying. The solid solution of Er and Zr decomposes to form a dispersion of secondary Al-3(ZrxEr1-x) during annealing. This secondary Al-3(ZrxEr1-x) precipitates improve strength, especially the elevated temperature strength. In the present paper we investigate the evolution of Al-3(ZrxEr1-x) precipitate during annealing by transmission electron microscopy (TEM). The Al-3(ZrxEr1-x) precipitates nucleate homogeneously at lower temperatures (280 degrees C and 470 degrees C). The transition from homogeneous to heterogeneous nucleation at higher aging temperature (510 degrees C) is a natural consequence of the reduced driving force for nucleus formation as the temperature increases and the Er supersaturation in the alpha-Al matrix decreases. The change in morphology of the Al-3(ZrxEr1-x) precipitates from faceted to approximately spheroidal is associated with a change in the value of interfacial free energies. The diameter and the ratio of Zr/Er increase with increasing aging time at constant temperature. The coarsening of Al-3(ZrxEr1-x) is dependent on the diffusivity of Er, Zr in alpha-Al.
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来源 :
ACTA METALLURGICA SINICA
ISSN: 0412-1961
年份: 2010
期: 7
卷: 46
页码: 850-856
2 . 3 0 0
JCR@2022
ESI学科: MATERIALS SCIENCE;
JCR分区:2
中科院分区:4