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The precipitation mechanism of the secondary phase in Inconel 617B alloy during ageing, Philosophical Magazine
Hui Lia , Mengchao Zhang a , Qiuyue Wu a , Qingdong Liu b, Zeming Wangc , Baoshun Wand
aKey Laboratory for Microstructures, School of Materials Science and Engineering, ShanghaiUniversity, Shanghai, People’s Republic of China;
bSchool of Materials Science and Engineering,Shanghai Jiao Tong University, Shanghai, People’s Republic of China;
cSchool of Materials Scienceand Engineering, Shanghai Institute of Technology, Shanghai, People’s Republic of China;
dZhejiangJiuli Hi-Tech Metals Co., Ltd., Huzhou, People’s Republic of China
Abstract:
Precipitation of the secondary phase is a key factor thatinfluences the strengthening effect of nickel-basedsuperalloy. The precipitation behaviours of the M 23C6carbide and γ′-Ni3(Ti, Al) phase in Inconel 617B alloy agedat 700°C for different times were studied by scanningelectron microscopy, transmission electron microscopy andatom probe tomography. Plate-like carbide nucleated inthe interior of grain and irregular shape carbideprecipitated at grain boundary respectively during the earlystage of ageing. γ′ particle co-precipitated around carbideis a common microstructure feature during ageing for 5–160 h. After ageing for 160 h, γ′ phase is the mainsecondary phase. The carbide only distributes on the grainboundary, high density γ′ particle homogeneouslydistributes in the matrix after a longer ageing time.Elemental partitioning to the secondary phases andcomposition profiles across different phases wasquantitatively analysed. Enrichments of Ti and Al at thecarbide/γ interface are directly observed, which act as thenucleation site of γ′ particles during ageing. Enrichments ofB, Si and Co at different interfaces are also detected. Basedon the experimental results, the precipitation mechanismsof γ′ particles and carbide were discussed.
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