A newly developed Ni-Fe-based weld metal has been researched for the microstructural and mechanical evolutions during prolonged thermal exposure using scanning electron microscopy and transmission electron microscopy. The M₂₃C₆-carbides precipitated at grain boundaries and around the primary (Nb, Ti)C phases in the Ni-Fe-based weld metal during prolonged exposure at 650 °C and 700 °C. The Cr, Mo-rich sigma(σ) and Cr-rich α-Cr formed as platelets and mainly located in the interdendritic areas during the exposure. σ phase had the orientation relationships of [001]_γ//[$11\bar{2}$]_σ, $(\bar{2}20)$_γ//$(\bar{1}10)$_σ and $(\bar{2}\bar{2}0)$_γ//$(111)$_σ with the γ matrix. Higher (Al + Ti) content accelerated the precipitation of these Cr-rich phases and resulted in a significant deterioration of tensile ductility after 5000 h at 700 °C. Precipitating and coarsening of spherical γ′ dominated the tensile strength evolution and the optimized γ′ radius with the best tensile strength was estimated to be 21–25 nm. (Al + Ti) content had no obvious effect on the γ′ coarsening rate but it affected the γ′ particle density N_s in two sides: On the one hand, higher (Al + Ti) content increased the N_s, which increased the 0.2% yield strength (R_p0.2)and tensile strength ( R_m). On the other hand, higher (Al + Ti) content increased the amount of σ phases which induced the γ′ envelopes to form and resulted in the decrease of N_s, and it would decreased the R_p0.2 and R_m.

使用扫描电子显微镜和透射电子显微镜，研究了一种新开发的镍铁基焊缝金属在长时间热暴露过程中的微观结构和机械演变。在长时间暴露于650°C和700°C的过程中，Ni-Fe基焊缝金属中的M ₂₃ C ₆碳化物在晶界处以及在主要（Nb，Ti）C相附近析出。Cr，富Mo的σ（σ）和富Cr的α-Cr形成为片状，并且在曝光过程中主要位于树突间区域。σ相的取向关系为[001] _γ // [$11\overline{\mathrm{2个}}$] _σ， $（\overline{\mathrm{2个}}\mathrm{2个}0）$_γ/ /$（\overline{\mathrm{1个}}\mathrm{1个}0）$_σ和$（\overline{\mathrm{2个}}\overline{\mathrm{2个}}0）$_γ //$（\mathrm{1个}\mathrm{1个}\mathrm{1个}）$带有γ矩阵的_σ。较高的（Al + Ti）含量会加速这些富Cr相的析出，并在700°C下经过5000 h后导致拉伸延展性显着降低。球形γ'的沉淀和粗化主导了抗拉强度的演变，具有最佳抗拉强度的最佳γ'半径估计为21–25 nm。（Al + Ti）含量对γ'粗化速率没有明显影响，但在两个方面都影响γ'颗粒密度N _s：一方面，较高的（Al + Ti）含量会增加N _s，从而增加N _s。 0.2％屈服强度（R _p0.2）和抗张强度（R _m）。另一方面，较高的（Al + Ti）含量会增加σ相的数量，从而导致γ'包膜的形成并导致N _s的减少，从而降低R _p0.2和R _m。