钨铈/可伐合金活性钎焊接头的组织与性能

Microstructure and proformances of active brazing joint of WCeO_2/Kovar alloy by vacuum brazing

采用含Ti的Ag-Cu基活性钎料真空钎焊钨铈合金(WCe O2)与可伐合金(4J33),并对接头结合强度与微观组织进行了研究。研究结果表明,焊接接头组织由富Ag相、富Cu相、Cu-Ti金属间化合物以及带状的(Fe,Co,Ni)-Ti化合物共同构成;最佳钎焊温度为850℃,此时钎料对WCe O2表面有良好的润湿性,且抗剪强度达到最大(153 MPa)。当钎焊温度较低时,母材及钎料中元素的扩散能力差、反应性弱,接头处不能形成良好的冶金结合并容易在界面处形成孔洞;而钎焊温度过高,焊缝组织中会形成过量的(Fe,Co,Ni)-Ti化合物,降低钎缝组织的塑韧性,导致接头综合力学性能下降。

The strength and microstructure of the brazed WCeO_2/4J33 joints using Ag-Cu-8Ti active brazing alloy were investigated in the paper.The microstructure of the joint showed that it consisted of Ag-rich phase,Cu-rich prase,Cu-Ti intermetallic compounds and(Fe,Co,Ni)-Ti compounds.The optimal wettability of the active filler on the surface of the WCeO_2 and the maximum shear strength of 153 MPa were reached at a brazing temperature of 850 V..Poor diffusion ability and reactivity between base metals and brazing filler metal lead to the bad metallurgical reaction and the formation of holes at the filler/WCeO_2 interfaces when the brazing temperature was below 850 ℃.However,a too high brazing temperature,such as larger than 850 ℃,resulted in the generation of excess(Fe,Co,Ni)-Ti compounds in the brazing seam,which reduced the mechanical properties of the joints.