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Indexed by:期刊论文

Date of Publication:2014-01-01

Journal:MATERIALS CHARACTERIZATION

Included Journals:SCIE、EI

Volume:87

Page Number:19-26

ISSN No.:1044-5803

Key Words:Solid solution; Precipitation; Microstructure; Phase transformation

Abstract:The precipitation in Al-Mg solid solution containing 21.6 at.% Mg prepared by solidification under 2 GPa was investigated. The results show that the gamma-Al12Mg17 phase is formed and the beta' phase cannot be observed in the solid solution during ageing process. The precipitation of gamma and beta phases takes place in a non-uniform manner during heating process, i.e. the gamma and beta phases are first formed in the interdendritic region, which is caused by the inhomogeneous distribution of Mg atoms in the solid solution solidified under high pressure. Peak splitting of X-ray diffraction patterns of Al(Mg) solid solution appears, and then disappears when the samples are aged at 423 K for different times, due to the non-uniform precipitation in Al-Mg solid solution. The direct transformation from the gamma to beta phase is observed after ageing at 423 K for 24 h. It is considered that the p phase is formed through a peritectoid reaction of alpha + gamma -> beta which needs the diffusion of Mg atoms across the interface of alpha/gamma phases. (C) 2013 Elsevier Inc. All rights reserved.