Mg-Gd-Y-Zn合金400℃热处理过程中长周期堆垛结构的形成  

Formation of long period stacking structure in Mg-Gd-Y-Zn alloy heat-treated at 400 ℃

作　　者：王飞[1] 孙威[1] 刘林林[1] 

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：《电子显微学报》2009年第4期361-366,共6页Journal of Chinese Electron Microscopy Society

基　　金：国家自然科学基金资助项目(No.50571002)~~

摘　　要：利用扫描电镜背散射电子像、透射电镜观察及能谱分析,研究了铸态MgGd1.8Y0.8Zn0.8(at.%)在400℃热处理前后结构的变化。结果发现,400℃热处理可导致铸态合金中初生Mg3Gd型第二相的部分分解及长周期堆垛结构(LPS)的形成。热处理形成的LPS结构为畸变的6H型,多存在于Mg3Gd型相及Mg5RE型相的前沿,并与较密集的堆垛层错(SF)组成一个富Zn元素的混合区——(SF+LPS)区。Mg5RE型相存在于热处理后的合金中,具有fcc结构,与Mg基体有确定的取向关系,其与(SF+LPS)区的相界处存在一个宽约10 nm的过渡层。SEM-BSE, TEM observations and EDS analysis have been applied to investigate the as-cast and heat-treated microstructures of the MgGd3.0 Y0.8 Zn0.8s （at. % ）alloy. The results show that, heat treatment at 400℃ can result in decomposition of the as-cast primary phases of the Mg3Gd type, and this is responsible for the formation of a long period stacking structure （LPS）. The LPS belongs to a distorted 6H type and it can grow together with stacking faults （SF） of high density to form a SF ＋ LPS mixing region adjoining the Mg3 Gd- and Mg5 Gd-type phases. The Mg5Gd-type phase, observed in the heat-treated alloy, has a fcc structure and definite orientational relationship with the Mg matrix. There exists a transitional layer about 10 nm in width along its phase boundary with the SF ＋ LPS region.

关 键 词：Mg—Gd—Y—Zn合金 热处理 第二相 长周期堆垛结构 堆垛层错 

分 类 号：TG115.215.3[金属学及工艺—物理冶金] TG146.22[金属学及工艺—金属学]