Mo含量对Inconel617合金晶界碳化物及高温拉伸性能的影响

Effect of Mo Content on Carbides at GBs and High-Temperature Tensile Properties of Inconel617 Alloy

摘要:

以在第4代核能系统具有重要应用背景的Inconel617合金为对象，采用热力学计算、SEM、TEM、EBSD和高温拉伸测试等手段，研究了Mo含量对Inconel617晶界碳化物析出和高温拉伸性能的影响。结果显示，当Mo含量为8wt%~9wt%时，合金晶界仅存在细小的颗粒状M₂₃C₆，而当Mo含量为9.3wt%~9.6wt%时，合金晶界上观察到大量粗大的块状M₂₃C₆和M₆C。随Mo含量由8wt%增加到9.6wt%，合金的伸长率呈现出先增大后减小的趋势，其中含8.5wt%~9.3wt% Mo的合金表现出良好的强塑性匹配。断口观察分析表明，由于颗粒状M₂₃C₆对晶界有较好的强化作用，合金高温拉伸断口呈现穿晶断裂特征，而当晶界处析出大尺寸M₆C和M₂₃C₆时，会促进沿晶裂纹形成，导致高温拉伸断口开始出现沿晶断裂特征。面向第4代核能系统高温部件应用的Inconel617合金Mo含量应不超过9.3wt%，建议控制在8.5wt%~9wt%。

Abstract:

Inconel617 alloy has significant application potential in Generation IV nuclear energy systems. The effects of Mo content on carbide precipitation at grain boundaries (GBs) and high-temperature tensile properties of Inconel617 alloy were studied by mechanical testing and advanced techniques such as scanning electron microscope, transmission electron microscope, and electron backscatter diffractometer. The results show that there are only fine granular M₂₃C₆ carbide at GBs when the Mo content ranges from 8wt% to 9wt%. However, as Mo content increases from 9.3wt% to 9.6wt%, massive M₂₃C₆ and M₆C carbides could be predominantly observed at GBs. As Mo content increases from 8.0wt% to 9.6wt%, the elongation increases initially and then decreases, and the alloys with the Mo content of 8.5wt%–9.3wt% achieve optimal strength-ductility balance. The fractographic analysis reveals that the precipitation of granular M₂₃C₆ at GBs effectively strengthens grain boundaries, resulting in the transgranular fracture features on the high-temperature tensile fracture surface. When massive M₂₃C₆ and M₆C carbides precipitate at GBs, the initiation of intergranular crack is promoted and the intergranular fracture features are observed on the high-temperature tensile fracture surface. The Mo content of Inconel617 alloy for high-temperature components in Generation IV nuclear systems cannot exceed 9.3wt% and it should be controlled with in the range of 8.5wt%-9wt%