Self-accommodated defect structures modifying the growth of Laves phase  

作　　者：Tong Yang Yi Kong Jiangbo Lu Zhenjun Zhang Mingjun Yang Ning Yan Kai Li Yong Du 

机构地区：[1]State Key Laboratory of Powder Metallurgy,Central South University,Changsha,410083,China [2]School of Physics and Information Technology,Shaanxi Normal University,Xi’an,710119,China [3]Materials Fatigue and Fracture Division,Institute of Metal Research,Chinese Academy of Sciences,Shenyang,110016,China [4]Institute for Materials Microstructure,Central South University,Changsha,410083,China

出　　处：《Journal of Materials Science & Technology》2021年第3期203-213,共11页材料科学技术（英文版）

基　　金：supported financially by the National Natural Science Foundation of China(Nos.51820105001,51771234,51531009 and 51790482);the Fundamental Research Funds for the Central Universities(No.GK201803016)。

摘　　要：Laves phases,with the topologically close-packed structure and a chemical formula of Ab_(2),constitute the largest single class of intermetallics.Planar defects in Laves phases are widely investigated,especially for stacking behavior transformations through synchroshear.Here,we report the coexistence of C14,C36 and C15 structures in MgZn_2 precipitates by using atomic resolution scanning transmission electron microscopy,verifying the previously predicted Laves phase transformation sequence of C14→C36→C15 also applies to MgZn_2.One type of stacking fault couple in precipitates has been found to alone reduce the lattice mismatch with matrix,while some other stacking fault couples need to self-accommodate with irregular planar defects(rhombic units and flattened hexagonal units),or with five-fold symmetry structures to relieve the strain concentration.Precipitates thus grow towards an equiaxed or even round morphology,rather than the plate morphology as conventionally believed.Molecular dynamics calculations are performed to support our analysis.These findings reveal the principles governing the concurrent occurrence of various defects in laves structures,acting as an update of the widely accepted perception of random occurrence of defects during crystal growth.

关 键 词：High angle annular dark field(HAADF) DEFECTS Stacking faults STRAIN 

分 类 号：O771[理学—晶体学]