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FGH96高温合金的再结晶主要包括孕育期、形核期和晶核长大期。再结晶形核与长大对温度非常敏感:当变形量较小时,在1050℃充分形核,在1080℃再结晶晶核等轴化过程稳定,能够得到均匀细小的等轴晶,而当温度高于1110℃时,再结晶等轴晶粒显著长大;随着变形量的增大,获得细晶粒的温度由1110℃降低到1080℃左右。促进形核、抑制晶粒长大均有利于晶粒细化。另外,再结晶优先在原始颗粒边界发生,当变形不充分时,内部残留未再结晶区,得到不完全再结晶组织,即“项链”组织。同时,这种组织也是粉末冶金材料晶粒细化过程中必然存在的中间态特征组织,随着变形方向的增加、累积变形量的增大,原始颗粒中心区域能够发生再结晶,“项链”组织也逐渐转化成等轴细晶组织。
The recrystallization of FGH96 superalloy mainly includes the period of gestation, nucleation and nuclei growth. The nucleation and growth of recrystallization is very sensitive to temperature. When the deformation is small, it is fully nucleated at 1050 ℃. The equiaxed nucleation process of recrystallized nuclei at 1080 ℃ is stable, and uniform and fine equiaxed grains can be obtained. When the temperature Higher than 1110 ℃, the recrystallized equiaxed grains grow significantly. With the increase of the deformation, the temperature of obtaining fine grains is reduced from 1110 ℃ to 1080 ℃. Promote nucleation, grain growth are inhibited are conducive to grain refinement. In addition, recrystallization preferentially occurs at the boundaries of the primary particles, and when the deformation is not sufficient, the recrystallized regions remain in the interior to give an incomplete recrystallized structure, ie, “necklace”. At the same time, this kind of structure is also an intermediate structure that is inevitable in grain refinement process of powder metallurgy materials. With the increase of deformation direction, the cumulative deformation increases and the recrystallization can occur in the central region of the original particle. Organizations are also gradually transformed into equiaxed fine-grained organizations.