In:
Materials Science Forum, Trans Tech Publications, Ltd., Vol. 783-786 ( 2014-05-23), p. 472-477
Abstract:
Microstructures and Vickers microhardness in AZ91 magnesium alloys without and with 1mass%Y addition fabricated by casting were investigated. Vickers microhardness increases with adding 1%Y. Microstructure in AZ91 without Y addition was analyzed to contain mainly α-Mg and Mg 17 Al 12 by X-ray diffraction. Microstructural observations with optical, scanning and transmission electron microscopes show that microstructure consists of α-Mg dendrite, non-equilibrium eutectic Mg 17 Al 12 and lamellar Mg 17 Al 12 . The non-equilibrium eutectic Mg 17 Al 12 exists between α-Mg dendrites. The lamellar Mg 17 Al 12 forms near the edge of the α-Mg dendrite arm. The lamellar Mg 17 Al 12 has Burgers orientation relationship for α-Mg matrix. It suggests that the lamellar Mg 17 Al 12 precipitates from Al-supersaturated region within α-Mg dendrite. Addition of Y to AZ91 hardly changes dendrite arm spacing, but decreases a size of region, where longitudinal directions of primary dendrite arms are almost parallel or a single dendrite exists. Y-addition increases nucleation site for dendrite, namely makes the unidirectionally-solidified region fine, resulting in increase in hardness.
Type of Medium:
Online Resource
ISSN:
1662-9752
DOI:
10.4028/www.scientific.net/MSF.783-786
DOI:
10.4028/www.scientific.net/MSF.783-786.472
Language:
Unknown
Publisher:
Trans Tech Publications, Ltd.
Publication Date:
2014
detail.hit.zdb_id:
2047372-2
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