Ni-34Ti钎料钎焊TiAl合金接头界面结构及性能

采用Ni-34Ti共晶钎料实现了TiAl合金的钎焊连接，分析了TiAl合金钎焊接头的界面结构，重点研究了钎焊温度对接头组织及性能的影响规律.结果表明,Ni-34Ti共晶钎料主要由TiNi相和TiNi3相组成，钎料熔点为1 120 ℃.不同钎焊温度下获得的接头界面组织均呈现对称特征，无气孔和裂纹等缺陷，接头中主要形成了TiNiAl2,B2,TiNiAl和TiNi2Al四种物相.Al元素在钎缝中的快速扩散，促进了钎缝中Ti-Ni-Al三元化合物的形成.钎焊温度为1 180 ℃保温10 min条件下，TiAl合金接头获得了最大的室温抗剪强度87 MPa.剪切过程中，裂纹容易在富含TiNi2Al相的区域产生和扩展，大量脆性TiNi2Al相的存在对接头的性能是有害的.

Interfacial microstructure and properties of TiAl alloy brazed joint with Ni-34Ti brazing alloy

TiAl alloy was successfully brazed using Ni 34Ti eutectic brazing alloy in this paper. The interfacial microstructure of TiAl brazed joints was characterized. In particular, the effects of brazing temperature on the interfacial microstructure and joining properties were investigated in details. Ni-34Ti eutectic brazing alloy was mainly composed of TiNi phase and TiNi3 phase. The melting point of this brazing alloy was about 1 120 ℃. The TiAl brazed joints presented a symmetrical characteristic. No pores and micro-cracks existed in the brazed joints. The microstructure analyses results showed that the brazed joints mainly consisted of TiNiAl2, B2, TiNiAl and TiNi2Al phases. The rapid diffusion of element Al in the brazed seam dominated the formation of Ti-Ni-Al ternary compounds. The maximum shear strength at room temperature reached 87 MPa when the joints were brazed at 1 180 ℃ for 10 min. The fracture analyses revealed that brittle fracture preferred to initiate and propagate in the TiNi2Al-rich region during shear test, which indicated that the existence of a large number of brittle TiNi2Al phases was harmful to the performance of TiAl brazed joints.