Formation and transformation of metastable LPSO building blocks clusters in Mg-Gd-Y-Zn-Zr alloys by spinodal decomposition and heterogeneous nucleation

作     者：Xin Zhao Zhong Yang Jiachen Zhang Minxian Liang Liying Wang 

作者机构：School of Materials Science and Chemical EngineeringXi’an Technological UniversityXi’an 710021China Xi’an Tianli Metal Composite Material Co.Ltd.Xi’an 710299China 

出 版 物：《Journal of Magnesium and Alloys》 (镁合金学报（英文）)

年 卷 期：2024年第12卷第2期

页      面：673-686页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：financially funded by Natural Science Basic Research Program of Shaanxi(grant number 2022JM-239) Key Research and Development Project of Shaanxi Provincial(grant number 2021LLRH-05–08) 

主　　题：LPSO Spinodal decomposition Homogenization treatment Clusters Phase transformation 

摘      要：To study the formation and transformation mechanism of long-period stacked ordered(LPSO)structures,a systematic atomic scale analysis was conducted for the structural evolution of long-period stacked ordered(LPSO)structures in the Mg-Gd-Y-Zn-Zr alloy annealed at 300℃~500℃.Various types of metastable LPSO building block clusters were found to exist in alloy structures at different temperatures,which precipitate during the solidification and homogenization *** stability of Zn/Y clusters is explained by the first principles of density functional *** LPSO structure is distinguished by the arrangement of its different Zn/Y enriched LPSO structural units,which comprises local fcc stacking sequences upon a tightly packed *** presence of solute atoms causes local lattice distortion,thereby enabling the rearrangement of Mg atoms in the different configurations in the local lattice,and local HCP-FCC transitions occur between Mg and Zn atoms occupying the nearest neighbor *** finding indicates that LPSO structures can generate necessary Schockley partial dislocations on specific slip surfaces,providing direct evidence of the transition from 18R to *** of the LPSO,devoid of any defects and non-coherent interfaces,was observed separately from other precipitated *** a result,the precipitation sequence of LPSO in the solidification stage was as follows:Zn/Ycluster+Mg layers→various metastable LPSO building block clusters→18R/24R LPSO;whereas the precipitation sequence of LPSO during homogenization treatment was observed to be as follows:18R LPSO→various metastable LPSO building block clusters→14H *** these,14H LPSO was found to be the most thermodynamically stable structure.