采用无B的含Hf镍基合金作为中间层合金, 分别对含Re的第二代镍基单晶高温合金 (CMSX-4, 铸态) 和第三代镍基单晶高温合金(SXG3, 完全热处理态)进行过渡液相(TLP)连接, 并分析了连接区的显微组织演变以及降熔元素分布, 测试了连接区的显微硬度. 结果表明, 在1290 ℃真空保温24 h后, CMSX-4和SXG3合金的TLP连接均已完成, 2种合金的TLP连接过程也均符合经典模型. 以含Hf的镍基合金作为中间层合金时, 在连接区内没有出现扩散影响区. CMSX-4合金的固溶处理可在TLP连接过程中同步完成, 缩短了热处理工艺. SXG3合金中的C与Hf结合在液相中形成固相HfC, 降低熔体中Hf浓度, 缩短了等温凝固阶段的时间. 研究表明, 通过含Hf的TLP连接可以研究小角度晶界的界面稳定性, 其中在1150 ℃保温热处理后, SXG3合金小角度晶界出现不连续脱溶转变的临界区间在10°~17°之间.

A Hf-containing Ni-based alloy was used as the interlayer alloy of TLP bonding for the 2nd (CMSX-4, as-cast condition) and 3rd (SXG3, standard heat treatment condition) generation Ni-based single crystal superalloys containing Re in this work, and the microstructure, composition and micro-hardness of bonding zone were characterized. The results show that the TLP bonding of CMSX-4 and SXG3 alloy were completed after bonded at 1290 ℃ in vacuum for 24 h. These TLP bonding process of CMSX-4 and SXG3 alloys can be explained well using classical TLP model. The diffusion affected zone was not observed during the TLP bonding process. In addition, the heat treatment process of CMSX-4 is shortened by 24 h resulted from the solid solution heat treatment of CMSX-4 alloy has been completed after the process of TLP bonding. The isothermal solidification stage of SXG3 alloy was also accelerated due to the precipitation of HfC at the bonding temperature, resulting in the reduced Hf concentration of Hf in the melting zone. This work also indicates that the interfacial stability of low angle grain boundaries can be investigated by the TLP bonding. The critical misorientation value for discontinuous precipitation of SXG3 alloy along TLP bonding grain boundaries by Hf-containing interlayer alloy was in between 10° and 17° after heat treatment at 1150 ℃.