TiAl基合金与Ni基合金钎焊连接接头界面组织及性能

Interfacial Microstructure and Properties of Brazing Joints of TiAl/Ni-Based Alloy

摘要:

采用BNi2钎料实现了TiAl基合金与Ni基高温合金的钎焊。采用扫描电镜、能谱分析和X射线衍射等手段对钎焊接头的界面组织结构及生成相进行分析，并对接头的抗剪强度进行测试。结果表明，钎焊接头的典型界面结构为：GH99/(Ni)ss (γ)+Ni3B+CrB+富Ti-硼化物/TiNi2Al/TiNiAl+Ti3Al/TiAl；随着钎焊温度的升高或保温时间的延长，较多的B和Si元素扩散进入两侧母材，导致钎缝中硼化物数量减少，而TiAl/钎缝界面的TiNi2Al和TiNiAl+Ti3Al金属间化合物层厚度增加；当钎焊温度为1050 ℃，保温时间为5 min时，接头的抗剪强度达到最大为205 MPa，接头主要断裂于TiNiAl金属间化合物层。当钎焊温度升高或保温时间继续延长时，TiNiAl厚度显著增加，导致接头强度下降

Abstract:

The BNi2 filler metal was used to join TiAl-based alloy to Ni-based alloy. Interfacial microstructure and formation phases of brazed joints were investigated by means of scanning electron, energy disperses spectroscopy and X-ray diffraction, and shear strength of the joints was determined. The results show that the typical interfacial microstructure of the joints is GH99/γ+Ni3B+CrB+rich Ti-boride/TiNi2Al/TiNiAl+Ti3Al/TiAl. With the increase of brazing temperature or holding time, more B and Si elements diffuse from the molten brazing filler metal into substrates, which decrease the amount of boride in the joint, while the thickness of TiNi2Al and TiNiAl+Ti3Al increases. When the brazing temperature T=1050 ℃ and the holding time t=5 min, the shear strength of the joints reaches a maximum of 205 MPa, and the joint is mainly fractured at TiNiAl intermetallic layer. Further increase the brazing temperature or holding time results in excessive growth of TiNiAl layer, which reduces the joining properties