TC4钛合金与碳碳复合材料钎焊接头组织与性能的研究

Microstructure and Mechanical Properties of TC4 Alloy/C/C Composite Brazed Joints

TC4钛合金与碳碳复合材料连接强度不高,严重限制其在飞行器发动机喷管方面的应用。采用Ag-Cu-(4.6 wt%)Ti+0.3 wt%Al_(2)O_(3)活性钎料分别在860~920℃,5~20 min条件下,对两者进行钎焊连接,测试不同工艺条件下的剪切强度,并通过扫描电子显微镜(SEM)、X射线衍射(XRD)等方法对钎缝及断口微观组织进行研究分析。结果表明:钎缝典型组织为TC4/Ti(s.s)/Ti_(2)Cu/TiCu/Ag(s.s)+Ti_(3)Cu_(4)+TiCu/TiC+TiO/碳碳复合材料。钎焊温度决定着反应能否发生,温度和时间的提高都会加剧母材的溶解,导致焊缝中Ti元素的增加,使层厚增长;当钎焊工艺参数为880℃/10 min时,接头的剪切强度最高,达到27.8 MPa。

Due to the low connection strength between C/C composite material and TC4 titanium alloy,its application in aviation engine nozzle is severely limited.Ag-Cu-(4.6 wt%) Ti+0.3 wt%Al_(2)O_(3)filler metal was used to join TC4 alloy and C/Ccomposite at 860-920℃for 5-20 min.The shear strength of the joints under different process was tested,and the microstructure of the joint and the fracture was analyzed by means of SEM and XRD.The results show that the typical interfacial microstructures of brazed joint are TC4/Ti (s.s)/Ti_(2)Cu/TiCu/Ag (s.s)+Ti_(3)Cu_(4)+TiC u/TiC+TiO/C/C composite.The brazing temperature determines whether the reaction could occur and the increase of temperature and holding time can intensify the dissolution of the base material,which leads to the increase of Ti element and the thickness of the reaction layer in the weld.The joint’s highest shear strength of 27.8 MPa is obtained at 880℃/10 min.