Formation and growth of precipitates in a Mg-7Gd-5Y-1Nd-2Zn-0.5Zr alloy aged at 200℃  

作　　者：Zhiwei Du Yonggang Peng Hang Teng Zhong Cao Kui Zhang Minglong Ma Xiaolei Han Ting Li Cong Che Yongjun Li 

机构地区：[1]Guobiao(Beijing)Testing&Certification Co.,Ltd.,Beijing 100088,China [2]China United Test&Certification Co.,Ltd.,Beijing 100088,China [3]Nanjing Yunhai Special Metal Co.,Ltd.,Nanjing 211212,China [4]Shanghai Spaceflight Precision Machinery Institute,Shanghai 201600,China [5]State Key Laboratory of Non-Ferrous Metals&Processes,GRIMAT Engineering Institute Co.,Ltd.,Beijing 101407,China

出　　处：《Journal of Magnesium and Alloys》2023年第7期2326-2339,共14页镁合金学报（英文）

基　　金：supported by the National Natural Science Foundation of China(51871195);Youth Fund Project of GRINM(G12620213129038);Henan Provincial Department of Science and Technology Research Project(No.222102230113).

摘　　要：Crystal structures,growth characteristics,and transformation of the precipitates in a Mg-7Gd-5Y-1Nd-2Zn-0.5Zr(wt.%)alloy aged at 200℃for various durations were investigated using transmission electron microscopy(TEM)and high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM).A detailed Mg-Gd type precipitation sequence for Mg-Gd-Y-Nd-Zn alloys was proposed as follows:supersaturated solid solution→solute clusters→zigzag GP zones+β''(I)→β'→β'+protrusions/joints→pre-β_(1)→β_(1)→β.Solute clusters formed in the early stage of aging consisted of one or more rare-earth(RE)/Zn-rich atomic columns with different configura-tions.RE/Zn-rich solute clusters grew into zigzag GP zones andβ''(I)as aging time extending.The paired-zigzag GP zones might grow up to beβ'precipitates directly.In the peak-and plat-aging stages,the number of solute clusters in the matrix decreased until they disappeared,and most existed as zigzag arrays and super hexagons.Protrusions formed at the end ofβ'at an angle of 120°,then grew into joints when two differentβ'variants encountered together.Protrusions/joints comprise zigzag arrays,super-hexagons,β'F,β''(II),β_(T),and hybrid structures rich in solute atoms,and act as catalysts for the growth of theβ'variants.Largerβ'grow by joints consumption while smallerβ'precipitates dissolve to form joints.β_(1)precipitates essentially evolve from pre-β_(1)precipitates,with four-point diamond structures formed by RE/Zn atomic substitution and atomic migration based on the originalα-Mg structure.

关 键 词：Magnesium alloys AGING PRECIPITATES MICROSTRUCTURES HAADF-STEM 

分 类 号：TG146.22[一般工业技术—材料科学与工程]