Mg-Gd-Nd合金极限高温时效析出相的研究
Study on Precipitating Phases in Mg-Gd-Nd Alloy Aged at Limiting High Temperature
谢中柱1,2, 许并社1, 孙 威3
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作者单位：(1.太原理工大学 新材料工程技术研究中心, 山西 太原 030024; 2. 太原大学 机电工程系, 山西 太原 030009; 3. 北京工业大学 固体微结构与性能研究所, 北京 100022)
中文关键字：Mg-Gd-Nd； 等温时效； 极限高温； 析出； β
英文关键字：Mg-Gd-Nd; isothermal aging; limiting high temperature; precipitation; β1
中文摘要：通过透射电子显微镜(TEM)观察并结合纳米束能谱(EDS)分析，研究了Mg96.9Gd2.8Nd0.3(at%)合金在极限服役温度300 ℃等温时效状态下析出相的形成和生长。确定了300 ℃等温时效析出序列为：MgS.S.S.S?邛β1(fcc)?邛β(fcc)，未见常规服役温度时效初期亚稳相β''和β'。镁基体中均匀弥散的面心立方结构的亚稳相β1成分为Mg7RE，是300 ℃时效合金的主要析出强化相。合金在300 ℃具有更快的时效硬化效应，但显著的过时效效应导致合金力学性能迅速下降。
英文摘要：The forming and growth of precipitating phases in Mg96.9Gd2.8Nd0.3(at%) alloy aged at limiting high temperature 300 ℃ was studied by TEM observations and nano-electron-probe EDS analysis. No evidence was found the presence of the early phases β" and β' in the Mg-Gd-Nd during aging at 300 ℃. A precipitating sequence of Mg(SSSS)?邛β1(fcc)?邛β(fcc) is suggested for this alloy. The metstable phase β1 has a f.c.c structure, it's homogeneous distribution in Mg matrix, which is the main precipitation strength phases. The composition of β1 is determined to be about Mg7RE by EDS. A rapid overageing response has been noted in the Mg-Gd-Nd alloy during ageing at 300 ℃ and this has been attributed to the rapid decrease of performance.