TiZrHfNbMo高熵合金与钛基复合材料钎焊接头组织及力学性能

Microstructure and mechanical properties of TiZrHfNbMo high-entropy alloy and Ti-based composites brazed joint

采用碳纳米管增强AgCuTi复合钎料真空钎焊TiZrHfNbMo高熵合金与钛基复合材料,通过X射线衍射仪、扫描电子显微镜、能谱分析仪、万能试验机等对接头显微组织与力学性能进行研究。结果表明:各焊接参数下均得到良好的焊接接头,焊缝组织由Ag(s,s)、Cu(s,s)、Ti(s,s)、CuTi、ZrCu和CuTi2组成;当钎焊保温时间一定时,随着钎焊温度升高,接头室温剪切强度呈现先升后降的趋势;一定量的Ti-Cu金属间化合物生成使反应层厚度加宽进而提高了接头强度,而过量的Ti-Cu金属间化合物生成使接头通过塑性变形缓解应力的能力减弱,导致接头强度大幅降低;当钎焊温度850℃,保温时间15 min时获得最佳焊接接头,其剪切强度达146 MPa,接头剪切断裂方式为脆性断裂。

TiZrHfNbMo high-entropy alloy and titanium matrix composite were vacuum brazed using carbon nanotubes reinforced AgCuTi composite filler. Microstructure and mechanical properties of the joints were systematically studied by X-ray diffractometer,scanning electron microscopy, energy spectrum and universal testing machine. The results show that the joints brazed at different temperatures from 820 °C to 910 °C for 15 min are successfully connected. The microstructure of the joint is composed of Ag(s,s),Cu(s,s), Ti(s,s), CuTi, ZrCu and CuTi2, the base material elements are fully diffused in the joint. When the brazing holding time is fixed, the shear strength of the joint at room temperature increases first and then decreases with the increase of brazing temperature.The formation of a certain amount of Ti-Cu intermetallic compounds widens the thickness of the reaction layer and improves the strength of the joint, while the formation of excessive Ti-Cu intermetallic compounds weakens the joint ability to relieve stress through plastic deformation, leading to a significant reduction in the joint strength. The best welded joint is obtained when the brazing temperature is 850 ℃ and the holding time is 15 min. The shear strength is up to 146 MPa, and the fracture mode of the shear fracture of the joint is brittle fracture.