涡轮盘用新型GH4975合金拉伸变形机制与温度的关联性

Temperature Dependence of Tensile Deformation Mechanism of GH4975 Superalloy for Turbine Disk

摘要:

通过光学显微镜（OM）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）系统研究了GH4975合金从25 ℃到1100 ℃之间的拉伸性能、变形机制及断裂行为。结果表明，该合金的变形机制由低温下的强耦合位错对剪切，转变至中温时的层错、微孪晶共同作用，当温度高于850 ℃后，位错绕过机制开始启动并随温度的升高逐渐主导位错运动。温度较低时碳化物裂纹主导了合金的开裂，随温度升高，晶界强度降低，晶界率先开裂成为裂纹源。晶界强度的降低和位错绕过机制的启动是合金高于800 ℃后强度迅速下降的主要原因。

Abstract:

Tensile properties, deformation mechanism, and fracture behavior of the GH4975 superalloy were investigated using optical microscope, scanning electron microscope, electron backscatter diffractometer, transmission electron microscope, and other advanced characterization techniques. The results show that the deformation mechanism of the alloy transitions from strong coupling dislocation shear at low temperatures to stacking fault and microtwin formation at intermediate temperatures. At temperatures higher than 850 °C, the dislocation bypass mechanism is activated and gradually dominates the dislocation movement with the increase in temperature. Carbide cracking dominates the failure of the alloy at low temperatures. As the temperature increases, the grain boundary strength decreases. Therefore, grain boundary cracks become the primary crack sources. At temperatures above 800 °C, the reduction in grain boundary strength and the activation of the dislocation bypass mechanism are the primary reasons for the rapid decline in alloy strength.