Study of age hardening in a Mg–2.2wt%Nd alloy by in situ synchrotron X-ray diffraction and mechanical tests
Study of age hardening in a Mg–2.2wt%Nd alloy by in situ synchrotron X-ray diffraction and mechanical tests
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研究％20of％20age％20硬化％20in％20a％20Mg-2.2wt％Nd％20合金％20by％20in％20原位％20同步加速器％20X射线％20衍射％20和％20机械％20测试
DOI：
10.1016/j.msea.2017.10.011
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Wenjiang Ding
中科院分区：
文献类型：
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作者：
Bijin Zhou;Leyun Wang;Bin Chen;Yiwang Jia;Wen Wen;Dejiang Li;Da Shu;Peipeng Jin;Xiaoqin Zeng;Wenjiang Ding
采用原位同步x射线衍射研究了过饱和固溶体Mg-2.2 wt%Nd合金在240°C时效6 h（阶段I）、295°C时效3 h（阶段II）和320°C时效1 h（阶段III）过程中的组织演变。在第1阶段，15min后观察到β1（Mg3Nd， FCC）析出物的衍射。通过峰强度和峰宽分析，估算了β1的体积、大小和长径比随时效时间的变化规律。在第II阶段，β（Mg12Nd，四方）析出物在~ 36 min后发生衍射，而β1仍留在材料中。在第三阶段，β1的体积相对于β显著减少。从原位时效实验中确定的沉淀序列得到了非原位电镜观察的支持。在时效阶段结束时，通过透射电子显微镜在材料中发现了同步x射线未检测到的β′。使用不同时效条件的试样进行拉伸和硬度测试，进一步了解不同析出物如何影响Mg-Nd合金的强度和延展性。
Microstructure evolution of a supersaturated solid solution Mg–2.2 wt%Nd alloy during aging at 240 °C for 6 h (stage I), at 295 °C for 3 h (stage II), and finally at 320 °C for 1 h (stage III) was studied by in situ synchrotron X-Ray diffraction. In stage I, diffraction fromβ1(Mg3Nd, FCC) precipitates was observed after ~ 15 min. Evolution of the volume, size, and aspect ratio ofβ1with the aging time were estimated from peak intensity and peak width analysis. In stage II, diffraction fromβ(Mg12Nd, tetragonal) precipitates was observed after ~ 36 min whileβ1remained in the material. In stage III, the volume ofβ1reduced substantially in relative toβ. The identified precipitation sequence from the in situ aging experiment is supported by ex situ electron microscopy observations.β′, which had not been detected by synchrotron X-rays, was additionally found using transmission electron microscopy in the material by the end of aging stage I. Tension and hardness tests using specimens with different aging conditions were further performed to understand how different precipitates affect the strength and ductility of the Mg–Nd alloy.