典型镍基高温合金的再结晶机理

Recrystallization Mechanism of Typical Ni-based Superalloys

研究了GH4760、GH4738和AD730典型镍基高温合金在热变形过程中的动态和静态再结晶行为,并进行了压缩热变形和固溶退火实验。结果表明,动态和静态再结晶的成核机制以涉及晶界凸起的不连续机理为主。在动态和静态再结晶过程中,普通晶面向低指数晶面转变,产生了不同类型的台阶晶界,这种转变将使更多的晶界具有较低的能量。Σ3晶界上阶梯边界的形貌大多分解为{111}_(1)/{111}_(2)和90°{112}_(1)/{112}_(2)小平面。台阶状晶界促进了晶界迁移,加速了再结晶过程。再结晶完成后,部分台阶晶界保留,界面能降低,促进了后续晶粒生长。

The dynamic and static recrystallization behavior of GH4760,GH4738,and AD730 typical Ni-based superalloys during hot deformation was investigated.The compressive hot deformation and solution annealing experiments were conducted.Results show that the nucleation mechanism of dynamic and static recrystallizations is dominated by the discontinuous mechanism of grain boundary bulging.Different types of stepped grain boundaries are generated during the dynamic and static recrystallizations due to the transformation from ordinary crystal planes into low-index crystal planes.This transformation results in lower energy of more grain boundaries.The morphology of the stepped boundaries onΣ3 grain boundaries mostly decompose into{111}_(1)/{111}_(2)and 90°{112}_(1)/{112}_(2)facets.The stepped grain boundaries promote the migration of grain boundaries,accelerating the recrystallization process.After recrystallization,partial stepped grain boundaries remain,the interfacial energy reduces,and the further grain growth is promoted.