The correlated mechanism of microstructural evolution and creep failure of N263 weld joint was studied in this paper. Results show that the creep failure presented in weld metal (WM), which initiated in the solute poor area near coarsened MC and/or M23C6 where Mo and Ti elements emigrated and merged with small MC/M23C6 to larger ones. Moreover, the crack propagated along the primary dendrite wall and second dendrite arm in which Mo and Ti are poor due to the precipitation and coarsening of MC/M23C6, which is caused by the different partition coefficient of main alloy elements during non-equilibrium solidification. However, the transition of decomposed MC to fine η phase during creep in WM is not responsible to crack initiation and propagation.

中文翻译：

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析出 Nimonic 263 高温合金焊接接头蠕变断裂与组织演变的相关机制

研究了N263焊接接头微观组织演变与蠕变破坏的相关机制。结果表明，蠕变失效出现在焊缝金属 (WM) 中，其起始于粗化 MC 和/或 M23C6 附近的溶质贫乏区域，其中 Mo 和 Ti 元素迁移并与小的 MC/M23C6 合并到较大的。此外，由于非平衡凝固过程中主要合金元素的分配系数不同，MC/M23C6的析出和粗化导致裂纹沿初枝晶壁和第二枝晶臂扩展，其中Mo和Ti较差。然而，在 WM 蠕变过程中分解的 MC 向细小的 η 相的转变不是裂纹萌生和扩展的原因。