摘要
An extremely high-strength TiAl/Ni-based superalloy dissimilar joint was obtained using a designed Ni_(25)Zr_(25)Sn_(20)Cu_(10)Hf_(10)Cr_(5)Fe_(5)multi-principal element interlayer via contact reaction brazing.It was found that a joint mainly composed of eutectic structure of(Ni)ss,(Ni,Cr,Fe)ss,and(Cr,Ni,Fe,Mo)ss,as well as micro-nano precipitates of(Ti)ss and(Hf,Zr)ss,could be achieved through the interaction between the interlayer and the base metals.The joint exhibited a shear strength of 498 MPa when brazed at 1190°C for 10 min,while the fracture occurred within the TiAl base metal,and the retention rate of high-temperature(HT)strength(650°C)was∼100%.The strengthening mechanism of the brazed joint was systematically discussed by transmission electron microscopy(TEM).It was shown that high-density dis-locations existed in each phase of the seam as well as twinning and stacking faults existed in the micro-nano precipitates,caused by a mass of solute atoms,greatly strengthened the joint.At HTs,the dislocation strengthening effect weakened due to grain recovery and recrystallization,but the joint could be addi-tionally toughened by multi-cracking.Meanwhile,granular(Ti)ss dispersed through the seam and ductile reticular structure(Ni)ss toughened the joint via the mechanism of crack termination and bridging.The proposed method provides a new approach for high strength and heat resistance joining of TiAl/Ni-based superalloy in aeroengine components.
基金
the financial support from the“National Natural Science Foundation of China(NSFC,Grant Nos.51974101,51975150,U21A20128,52175302 and U22A20185)”
“National MCF Energy R&D Program(No.2019YFE03100100)”
“Fundamental Research Funds for the Central Universities(Nos.2022FRFK060009 and HIT.DZJJ.2023011)”
“Natural Science Foundation of Heilongjiang Province,China(No.JQ2020E003)”.
