TiAl/Ni基合金反应钎焊接头的微观组织及剪切强度

摘要

Reactive brazing of TiAl-based intermetallics and Ni-based alloy with Ti foil as interlayer was investigated.The interfacial microstructure and shear strength of the joints were studied.According to the experimental observations,the molten interlayer reacts vigorously with base metals,forming several continuous reaction layers.The typical interfacial microstructure of the joint can be expressed as GH99/ (Ni,Cr)ss (γ)/TiNi (β2)+TiNi2Al (τ4)+Ti2Ni (δ)/δ+Ti3Al (α2)+Al3NiTi2 (τ3)/α2 +τ3/TiAl.The maximum shear strength is 258 MPa for the specimen brazed at 1000 ℃ for 10 min.Higher brazing temperature or longer brazing time causes coarsening of the phases in the brazing seam and formation of brittle intermetallic layer,which greatly depresses the shear strength of the joints.%以Ti为中间层,对TiAl基金属间化合物与Ni基高温合金进行反应钎焊连接,研究反应钎焊接头的界面微观结构及剪切强度.通过实验发现,熔融中间层与两侧母材反应剧烈,生成连续的界面反应层.典型的界面微观结构为GH99/(Ni,Cr)ss(γ)/TiNi (β2)+TiNi2Al(τ4)+Ti2Ni (δ)/δ+Ti3Al (α2)+Al3NiTi2 (τ3)/α2+τ3/TiAl.当钎焊温度为1000℃,保温时间10 min时,所得接头的剪切强度最高为258MPa.进一步升高钎焊温度或延长保温时间,会引起钎缝组织中组成相粗化和脆性金属间化合物层的生成,从而导致接头剪切强度的降低.