摘要
At temperatures ranging from 760 to 1100 °C, the tensile properties of a nickel-based third generation single crystal superalloy DD9 with [100],[120] and [110] orientations were studied. The microstructures and fracture surfaces were observed by OM, SEM and TEM. Results show that the tensile strength of [100] specimen is higher than that of [120] and [110] specimens at 760 and 850 °C;while at the temperatures higher than 980 °C, the tensile strength of all specimens has little difference. The fracture mechanisms of [100],[120] and [110] specimens are the same at 760 and 980 °C. At 1100 °C, the fracture surfaces of [100] and [120] specimens are characterized by dimple features;while [110] specimen shows mixed quasi-cleavage and dimple featured fracture surfaces. At 760 °C, obvious superlattice stacking faults (SSFs) are observed only in [100] specimen;while at 1100 °C, the dislocation configurations of all specimens are similar. The difference in the number of potential active slip systems in [100],[120] and [110] specimens during the tensile deformation process is the main reason for the transverse tensile anisotropy.
研究[100]、[120]和[110]取向的镍基第三代单晶高温合金DD9在760～1100℃范围内的拉伸性能。采用OM、SEM和TEM观察显微组织与断口形貌。结果表明,[100]取向试样在760℃和850℃的抗拉强度高于[210]和[110]取向试样,而在980℃以上,三种取向试样的抗拉强度接近。[100]、[120]和[110]取向试样在760℃与980℃的断裂机制相同,而在1100℃条件下,[100]与[120]取向试样断口为韧窝断裂,而[110]取向试样断口为类解理断裂与韧窝断裂共存。在760℃条件下,仅在[100]取向试样中发现明显层错,而在1100℃条件下三种取向试样中位错组态相似。[100]、[120]和[110]取向试样拉伸变形过程中可开动的潜在滑移系数量不同是造成横向拉伸性能各向异性的主要原因。
