保温时间对DD407镍基单晶TLP修复区界面组织的影响

Effect of holding time on the interfacial microstructures of the TLP repair joints of Nickel - Based Single Crystal DD407Xie Jilin1 , Huang Yongde1 2,Chen Yuhua1,Zhang Timing,Wang Shanlin,Hao Kun,Zhang Chengcong3

摘要:

通过使用BNi5合金钎料对DD407镍基单晶合金的模拟缺陷进行了焊接修复。采用光学显微镜（OM）、扫描电子显微镜（SEM）和微区XRD系统研究了修复区界面的微观组织、析出相、元素分布。结果表明：采用膏状BNi5合金能够对DD407镍基单晶的模拟缺陷进行局部修复。在修复区与母材之间会形成反应界面层，在反应层存在由于元素扩散引起的元素梯度分布，且会析出白色的Cr6Ni16Si7颗粒，随着保温时间延长，颗粒数量越多。随着保温时间的增加，修复区的界面宽度逐渐增加。当保温时间为120min时，界面宽度最大，约为224μm，完全采用BNi5合金作为修复填充金属是导致界面宽度随保温时间增加而增加的主要原因。但采用膏状BNi5合金作为填充材料对模拟缺陷进行修复无法完全复原试样的原始尺寸，还需要深入研究填充合金的成分和类型；同时，还需要进一步延长扩散时间，进而获得均匀的组织，为镍基单晶合金的TLP修复奠定基础。

Abstract:

The simulation defects in the Nickel - Based Single Crystal DD407 alloy were repaired by BNi5 brazer . The microstructures, precipitates and element distribution of the repaired joint were observed and analyzed by optical microscope (OM), scanning electron microscopy (SEM) and micro XRD test techniques. The results show that simulation defects can be locally repaired by adopting paste BNi5 alloy. A reaction interface with elemental gradient and white Cr6Ni16Si7 particles was formed between the repaired zone and the base metal. The amount of the Cr6Ni16Si7 particles and the width of the interface were increased as the increasing of the holding time. When the holding time is 120min, the interfacial width reached the maximum value which is approximately 224μm. Only adopted the BNi5 alloy as the filler material is the main reason responsible for the interfacial width increasing as the holding time. Further analysis of the content and the type of the filler material was needed to obtain a completely repaired defects in shape and size. Moreover, further extend the diffusion time was also needed to achieve a uniform TLP microstructure which is a foundation for TLP repair processing of nickel-based single crystal alloys.