Microstructure and properties of pulse current promoted diffusion welding TiAl/Ti2AlNb joint with Ti69NbCrZrX interlayer
The novel Ti69NbCrZr X(X=Sn,W,Al,Mo,1%-2%,mass fraction)was used as an interlayer to join TiAl alloy with Ti2AlNb alloy by pulsed current diffusion welding at 900℃/30 min/8 MPa.The post-weld joint microstructure and properties were analyzed by SEM,EDS,EBSD,and room temperature tensile test.The results show that defect-free TiAl/Ti2AlNb joints can be obtained using Ti69NbCrZr X as the connecting interlayer.The joint interface microstructure is mainly composed of TiAl diffusion affected zone,interlayer diffusion zone,and Ti2AlNb diffusion affected zone.The TiAl diffusion affected zone structure is composed of white β phase and gray block α2 phase,the interlayer diffusion zone structure is mainly composed of gray block α2+α phase,and white β/B2 phase composition,Ti2AlNb diffusion affected zone is composed of β/B2 matrix phase with lath and acicular O phase.The average value of room temperature tensile strength of the joint is 642.5 MPa,which reaches 91.57%of the strength of the base material.The fracture mode of the joints is dominated by brittle intergranular fracture,supplemented by brittle transgranular fracture.
TiAlTi2AlNbpulse current promoting diffusion weldinginterlayer
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