Influence of Co content on the microstructures and mechanical properties of a Ni-Co base superalloy made by specific additive manufacturing process
Influence of Co content on the microstructures and mechanical properties of a Ni-Co base superalloy made by specific additive manufacturing process
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Co含量对特定增材制造镍钴基高温合金显微组织和力学性能的影响
DOI：
10.1016/j.msea.2020.139438
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发表时间：
2020
期刊：
影响因子：
6.4
通讯作者：
Ding Yutian
中科院分区：
文献类型：
--
作者：
Tang Ling;Liang Jingjing;Cui Chuanyong;Li Jinguo;Zhou Yizhou;Sun Xiaofeng;Ding Yutian
采用增材制造技术制备了不同Co含量的Ni-Co基高温合金，研究了该合金在标准热处理后的组织和拉伸性能。扫描电子显微镜（SEM）观察表明，在5Co合金中，枝晶间有大量η相析出，并沿柱状晶组织呈沿着分布。透射电镜（TEM）结果表明，5Co合金中存在球形γ′相，23 Co合金中存在近立方形γ′相。两种合金中γ′相的不同形貌可归因于γ′相成分的不同和γ/γ′晶格失配度的不同。拉伸试验结果表明，在低于500 °C的温度下，AM制备的合金的极限强度和延伸率低于铸轧（C&W）合金。当在750 °C和800 °C下测试时，由AM制成的合金表现出更高的屈服强度和上级塑性。随着试验温度的升高，合金的变形机制由位错滑移转变为层错剪切和形变孪晶。Co含量的增加降低了层错能（SFE），促进了孪晶的萌生，因此AM法制备的5Co合金与23 Co合金的变形机制有显著差异。
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 η 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 γ′ phase can be found in 5Co alloy and nearly cuboidal γ′ phase can been observed in 23Co alloy. The different morphologies of the γ′ precipitate can be attributed to the different γ′ compositions and the differences in γ/γ′ lattice misfit in the two alloys. The results of tensile tests reveal that, when tested below 500 °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 °C and 800 °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.