Strong and ductile heat-treatable Mg-Sn-Zn-Al wrought alloys

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• 作者：T.T. Sasaki^a ; ^{SASAKI.Taisuke@nims.go.jp" class="auth_mail" title="E-mail the corresponding author} ; F.R. Elsayed^a ; ^b ; T. Nakata^c ; T. Ohkubo^a ; S. Kamado^c ; K. Hono^a ; ^b
• 关键词：Mg&ndash ; Sn ; Precipitation hardening ; Extrusion ; Microalloying
• 刊名：Acta Materialia
• 出版年：2015
• 出版时间：15 October 2015
• 年：2015
• 卷：99
• 期：Complete
• 页码：176-186
• 全文大小：6119 K

文摘

A newly developed Mg–Sn–Zn–Al based alloy shows substantial strengthening by artificial aging. A Na-doped Mg–5.4Sn–4.2Zn–2.0Al–0.2Mn–0.1Na (TZAM5420−0.1Na) (wt.%) alloy exhibited a significant increase in yield strength from 243 to 347 MPa by a T6 treatment due to the uniform dispersion of nanoscale precipitates by aging. The trace addition of Na causes the formation of Sn–Na co-clusters in the early stage of aging, which provides heterogeneous nucleation sites for Mg₂Sn precipitates. However, Na strongly segregates at grain boundaries and this degrades the ductility significantly. To overcome this problem, we developed a Na-free Mg–6.6Sn–5.9Zn–2.0Al–0.2Mn (TZAM6620) alloy, in which nano-scale MgZn₂ precipitates are uniformly dispersed by double aging. Pre-aging caused the formation of Zn-rich Guinier Preston zones, which acted as heterogeneous nucleation sites for the MgZn₂ precipitates. The double-aged TZAM6620 alloy exhibited a very high yield strength of 370 MPa with large elongation of 14%.