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

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.

Key words:Ni-based Single crystal superalloy; brazing repair; diffusion time; interfacial microstructure