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Indexed by:期刊论文

Date of Publication:2015-01-01

Journal:Acta Metallurgica Sinica-English Letters

Included Journals:SCIE、EI、Scopus

Volume:28

Issue:1

Page Number:115-121

ISSN No.:1006-7191

Key Words:Mg-Al-Zn-Sb alloy; Solidification pathways; Nucleation; Grain size; Dendrite coherency

Abstract:The phase constitution and solidification pathways of AZ91 + xSb (x = 0, 0.1, 0.5, 1, in wt%) alloys were investigated through ways of microstructure observation, thermal analysis technique, and thermodynamic calculation. It was found that the non-equilibrium solidification microstructure of AZ91 + xSb (x = 0.1, 0.5, 1) is composed of alpha-Mg matrix, beta-Mg17Al12 phase, and intermetallic compound Mg3Sb2. The grain size of the alloys with different Sb contents was quantitatively determined by electron backscattered diffraction technique which shows no grain refinement in Sb-containing AZ91 alloy. Thermodynamic calculations are in reasonable agreement with thermal analysis results, showing that the Mg3Sb2 phase forms after alpha-Mg nucleation, thus impossible acts as heterogeneous nucleus for alpha-Mg dendrite. Besides, the solid fraction at dendrite coherency point (f(s)(DCP)) determined from thermal analysis decreases slightly with increasing Sb content, which is consistent with the fact that Sb does not refine the grain size of AZ91 alloy.