Mg-Gd-Y合金中与β'相粗化相关的析出结构  

Precipitation Structures Associated Withβ'Phase Coarsening in a Mg-Gd-Y Alloy

作　　者：刘林林[1] 孙鹏阳 孙威[1] 刘翠秀[1] LIU Linlin;SUN Pengyang;SUN Wei;LIU Cuixiu(Institute of Microstructure and Property of Advanced Materials,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学固体微结构与性能研究所,北京100124

出　　处：《北京工业大学学报》2022年第2期164-175,共12页Journal of Beijing University of Technology

基　　金：国家自然科学基金资助项目(11274027);北京市自然科学基金资助项目(2092005)。

摘　　要：为了研究Mg_(97)Gd_(2)Y_(1)合金中β'相的粗化过程以及相关析出结构的形成和演变机制,使用原子分辨的高角度环形暗场-扫描透射电子显微镜(high angle annular dark field scanning transmission electron microscope,HAADF-STEM)成像技术表征了合金不同时效阶段形成的析出结构,并结合第一性原理计算的方法分析了它们的稳定性.结果表明,相关的β_(F)'、β_(M)和β″相主要在β'相粗化过程的早期形成,它们的形成与β'相相界面周围存在较高的错配应变场密切相关;随着β'相粗化过程的进行,β_(M)和β″相的尺寸和数量逐渐减少,而由β'与β_(F)'相交替组成的竹节状析出物增多,成为合金基体中主要的析出结构;当错配应变足够大时,β_(F)'相内部出现位错,β相在位错处可以形核,并逐渐长大成为基体中主要的平衡析出结构.To study the coarsening process of the β' phases and the formation and evolution mechanisms of the associated precipitation structures in Mg_(97)Gd_(2)Y_(1) alloy,the precipitation structures formed in different aging stages were characterized by using atomic scaled high angle annular dark field scanning transmission electron microscope(HAADF-STEM)imaging technique and their stabilities with the aid of first principle calculation method were analyzed.Results show that the relevant β_(F)',β_(M)andβ″precipitates are formed mainly in the early stage of theβ'phases coarsening process.Their formation is closely related to existence of the high internal mismatch strain field around the interface ofβ'phases.With the progress of coarsening process for theβ'phases,theβ_(M)andβ″precipitates are gradually reduced in both sizes and amounts and instead the bamboo-like precipitates composed of β' and β_(F)' precipitates increase.When the mismatch strain is large enough,some dislocations will occur in the β_(F)' precipitates,at which theβphases can nucleate and then gradually grow up as major equilibrium precipitates.

关 键 词：MG-GD-Y合金 析出相 微观结构 粗化 演变机制 高角度环形暗场-扫描透射电子显微镜 

分 类 号：TG146.1[一般工业技术—材料科学与工程]