Effect of Zn additions on the age-hardening of Mg-2.0Gd-1.2Y-0.2Zr alloys

被引:451
作者
Honma, T.
Ohkubo, T.
Kamado, S.
Hono, K.
机构
[1] Univ Tsukuba, Grad Sch Pure & Appl Sci, Tsukuba, Ibaraki 3050047, Japan
[2] Natl Inst Mat Sci, Tsukuba, Ibaraki 3050047, Japan
[3] Nagaoka Univ Technol, Dept Mech Engn, Nagaoka, Niigata 9402188, Japan
关键词
magnesium-gadolinium-yttrium-zinc-zirconium alloy; rare-earth; three-dimensional atom probe; precipitation;
D O I
10.1016/j.actamat.2007.02.036
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
We have investigated the microstructures of age hardened Mg-2.0Gd-1.2Y-xZn-0.2Zr (x = 0, 0.3, and 1.0) (at.%) alloys to understand the remarkable age-hardening and unusual plastic elongation behavior. The age-hardening of the alloys occurs through the sequential precipitations of beta' and beta(1) phases. The beta(1) phase heterogeneously nucleates at the interface of the beta' phase, and relaxes strain fields around the beta'. Although the addition of Zn degrades the age-hardening response, it causes the discontinuous precipitation of a 14H-type long-period stacking (LPS) phase at grain boundaries as well as within grains in the over-aged condition, which enhances the maximum tensile elongation. The composition of the beta(1) phase was determined to be Mg-23.3 at.% RE-9.7 at.% Zn-2.0 at.% Zr (RE: rare-earth, Gd and Y), whereas that of the LPS is Mg-5.6 at.% RE-1.8 at.% Zn-1.0 at.% Zr. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
引用
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页码:4137 / 4150
页数:14
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