Mg97Zn1Y2（at.%）合金中14H型长周期相室温拉伸变形结构电子显微学表征

Mg₉₇Zn₁Y₂（at.%）合金中14H型长周期相室温拉伸变形结构电子显微学表征

李东伟，孙  威^*

（北京工业大学固体微结构与性能研究所，北京  100124）

摘  要  本文采用聚焦离子束切割技术，精确切取了固溶Mg₉₇Zn₁Y₂ (at.%)合金室温拉伸样品中LPSO相及其周边镁基体的拉伸变形结构。采用高分辨透射电子显微学方法并结合HAADF-STEM技术对合金中14H型LPSO相及周边镁基体的变形结构进行了表征和分析。研究结果清楚地揭示了LPSO板条在拉伸应力下可以同时通过基面滑移和扭折两种方式协调基体变形。基面滑移优先发生在LPSO板条中与基面平行的残余纳米薄Mg层处，并沿LPSO/Mg界面开动形成明显的表面台阶。而在局域应力集中的作用下，扭折变形除了开动常见的基面位错外还证实有非常见的柱面位错的参与。

关键词   Mg-Zn-Y合金；长周期相；变形结构；电子显微学表征

中图分类号：

文献标识码：Adoi:10.3969/j.issn.1000-6281.2020.06.006

Electron microscopy characterization of the tensile deformation microstructure of 14H-type LPSO phase in the Mg₉₇Zn₁Y₂(at.%)alloy deformed at room temperature

LI Dong-wei，SUN Wei^*

（Institute of Microstructure and Property of Advanced Materials，Beijing University of Technology，beijing 100124，China）

Abstract  In this study, the focused ion beam(FIB) technique was applied to precisely slice the LPSO phase deformed with the Mg matrix in the Mg₉₇Zn₁Y₂(at.%)alloy subjected to solution treatment and subsequent tensile deformation at room temperature. The deformation structure in 14H-type LPSO phase and the surrounding Mg matrix had been characterized by a combination of high resolution transmission electron microscopy and HAADF-STEM techniques. The results clearly illustrate that a LPSO plate phase in the matrix can accommodate matrix deformation through both basal sliding and kinking under a tensile stress condition. The basal sliding was observed to occur preferentially in nano-thin basal Mg layers retained in LPSO plate, and more specifically to occur along the LPSO/Mg phase boundaries through which surface deformation steps could be formed. For the kinking deformation in the LPSO plate, it has been confirmed that, in addition to those usual basal dislocations, the unusual prismatic dislocations could also be activated to involve in the kinking due to local stress concentration.

Keywords Mg-Zn-Y alloy; LPSO phase; deformation structure; electron microscopy characterization

“全文下载请到同方知网，万方数据库或重庆维普等数据库中下载！” 

[1] 毕建军，刘翠秀，李万鹏，等. Mg-Y合金中共轴{11`21}孪晶交互的电子显微研究[J].电子显微学报，2019，38(5):496-501.

[2] ANTION C, DONNADIEU P, PERRARD F, et al. Hardening precipitation in a Mg-4Y-3RE alloy[J]. Acta Materialia，2003，51(18): 5335-5348.

[3] MENGUCCI P，BARUCCA G，RIONTINO G，et al. Structure evolution of a WE43 Mg alloy submitted to different thermal treatments[J].  Materials Science & Engineering A，2008,479(1): 37-44.

[4] PING D H，HONO K，NIE J F. Atom probe characterization of plate-like precipitates in a Mg-RE-Zn-Zr casting alloy[J]. Scripta Materialia, 2003,48(8): 1017-1022.

[5] KAWAMURA Y,HAYASHI K, INOUE A, et al. Rapidly solidified powder metallurgy Mg_97 Zn_1 Y_2 alloys with excellent tensile yield strength above 600 MPa[J]. Materials Transactions, 2001,42(7): 1172-1176.

[6] ZHU Y M, MORTON A J, NIE J F. The 18R and 14H long-period stacking ordered structures in Mg-Y-Zn alloys[J]. Acta Materialia, 2010, 58(8): 2936-2947.

[7] ZHANG H，LIU C Q, ZHU Y M , et al. Revisiting building block ordering of long-period stacking ordered structures in Mg-Y-Al alloys[J].  Acta Materialia, 2018,152:96-106.

[8] MATSUDA M, II S, KAWAMURA Y, et al. Variation of long-period stacking order structures in rapidly solidified Mg₉₇Zn₁Y₂ alloy[J]. Materials Science Engineering A, 2005, 393(1/2): 269-274.

[9] KISHIDA K,NAGAI K, MATSUMOTO A, et al. Crystal structures of highly-ordered longperiod stacking-ordered phases with 18R, 14H and 10H-type stacking sequences in the Mg-Zn-Y system[J]. Acta Materialia, 2015, 99: 228-239.

[10] WANG W Y, SHANG S L, WANG Y,et al. Electronic structures of long periodic stacking order structures in Mg: a first-principles study[J]. Journal of Alloys & Compounds, 2014, 586: 656-662.

[11] LIU H,YAN K, Yan J L, et al. Precipitation behavior of 14H LPSO structure in single 18R phase Mg–Y–Zn alloy during annealing at 773 K[J]. Transactions of Nonferrous Metals Society of China, 2017,27(1): 63-72.

[12] KIM J K, SANDLOBES S, RAABE D. On the room temperature deformation mechanisms of a Mg-Y-Zn alloy with long-period-stacking-ordered structures[J]. Acta Materialia, 2015, 82: 414-423.

[13] LENG Z, PAN H, Guo C, et al. Asymmetry of tensile-compressive mechanical behaviors of Mg-RE-Zn alloy strengthened by long period stacking ordered phase[J]. Materials Science and Engineering, 2016, 667: 468-472.

[14] HAGIHARA K, MASAHITO H, MATSUMOTO R, et al.In-situ observation on the formation behavior of the deformation kink bands in Zn single crystal and LPSO phase[J]. Materials Transactions, 2015, 56(5): 943-951.

[15] CHEN R, SANDLOEBES S, ZEHNDER C,et al. Deformation mechanisms, activated slip systems and critical resolved shear stresses in an Mg-LPSO alloy studied by micro-pillar compression[J]. Materials & Design, 2018, 154: 203-216.

[16] CHUANG W S, HSIEH C H, HUANG J C, et al. Relation between sample size and deformation mechanism in Mg-Zn-Y 18R-LPSO single crystals[J]. Intermetallics,  2017, 91: 110-119.

[17] TAKAGI K, MAYAMA T, MINE Y, et al. Extended ductility due to kink band formation and growth under tensile loading in single crystals of Mg-Zn-Y alloy with 18R-LPSO structure[J]. Journal of Alloys and Compounds, 2019, 806: 1384-1393.

[18] HAGIHARA K, SUGINO Y, FUKUSUMI Y, et al. Plastic deformation behavior of Mg12ZnY LPSO-phase with 14H-typed structure[J]. Materials Transactions, 2011, 52(6): 1096-1103.

[19] SHAO X H, YANG Z Q, MA X L. Strengthening and toughening mechanisms in Mg-Zn-Y alloy with a long period stacking ordered structure[J]. Acta Materialia, 2010, 58(14): 4760-4771.

[20] EGUSA D, YAMASAKI M, KAWAMURA Y, et al. Micro-kinking of the long-period stacking/order (LPSO) phase in a hot-extruded Mg₉₇Zn₁Y₂alloy (special issue on long-period stacking ordered structure and its related materials(1))[J]. Materials Transactions, 2013, 54: 698-702.