期刊
出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.msea.2020.139438
关键词
Additive manufacturing; Ni-Co base Superalloy; Tensile strength; Deformation mechanism
类别
资金
- National Key R&D Program of China [2017FB1103800, 2018FB1106600, 2017YFA0700703, 2018FB1106000, 2019YFA0705304]
- National Natural Science Foundation of China (NSFC) [51771190, 51671189, U1508213]
- National High Technology Research and Development Program (863) [2014AA041701]
- State Key Laboratory of Solidification Processing in NWPU [SKLSP201834]
Microstructures and tensile properties of a Ni-Co base superalloy containing different Co contents made by additive manufacturing (AM) after standard heat treatment have been investigated. Microstructure observation by scanning electron microscopy (SEM) reveals that a great deal of eta precipitates form in the interdendritic region and distribute linearly along the columnar microstructure in 5Co alloy. In addition, transmission electron microscopy (TEM) results reveal that spherical gamma' phase can be found in 5Co alloy and nearly cuboidal gamma' phase can been observed in 23Co alloy. The different morphologies of the gamma' precipitate can be attributed to the different gamma' compositions and the differences in gamma/gamma' lattice misfit in the two alloys. The results of tensile tests reveal that, when tested below 500 degrees C, the ultimate strength and the elongation of the alloys made by AM are lower than that of the cast & wrought (C&W) alloys. When tested at 750 degrees C and 800 degrees C, alloys made by AM exhibit higher yield strength and superior plasticity. With the increment of the testing temperature, deformation mechanism of the alloys transforms from dislocation glide to stacking fault shearing and deformation twinning. Increasing of Co content can decrease the stacking fault energy (SFE) and facilitate the initiation of twinning, therefore, deformation mechanisms between the 5Co alloy and 23Co alloy made by AM are of notable difference.
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