钛基钎料高温钎焊TZM界面行为及热稳定性研究

Interfacial Behavior and Thermostability of the TZM High Temperature Brazing Seam with Ti-based Brazing Filler Metals

摘要:

采用Ti-8.5Si、Ti-33Cr和Ti-30V-3Mo钎料实现了钛锆钼(TZM)合金的高温真空钎焊连接,借助SEM、EDS及润湿性试验和抗剪试验等分析试验方法,研究了钛基钎料高温钎焊TZM及钎焊接头经高温热循环后的热稳定性。结果表明,Ti-8.5Si、Ti-33Cr在1520℃/6min的工艺条件下良好润湿TZM,润湿角分别为10°和9°,Ti-8.5Si钎料的铺展面积大于Ti-33Cr钎料的铺展面积,Ti-30V-3Mo钎料在1680℃/8min的条件下在TZM板上的润湿角为5°。Ti-8.5Si/TZM接头界面形成(Ti,Mo)固溶体,钎缝中心由(Ti,Mo)固溶体和Ti₅Si₃相组成。Ti-33Cr/TZM接头界面形成(Ti,Mo)固溶体,钎缝中心由(βTi,Cr)固溶体和αTi+(αTi+αTiCr₂)共晶组成。Ti-30V-3Mo/TZM接头,钎缝区主要由(βTi,V)固溶体和αTi组成,界面区由Ti与Mo形成(Ti,Mo)固溶体。三种钎料钎焊TZM,均形成固溶体钎焊接头而实现钎料与TZM的冶金结合,钎焊接头强度分别为135.8MPa(Ti-8.5Si)、132MPa(Ti-33Cr)和131MPa(Ti-30V-3Mo)。Ti-8.5Si/TZM、Ti-33Cr/TZM接头经过1200℃/60min没有观察到明显的晶间渗入和母材溶蚀,界面固溶体结合形式无变化。Ti-30V-3Mo/TZM接头经过1550℃/60min热循环后,观察到1个晶粒深度的晶间腐蚀,没有明显的母材溶蚀现象,且界面依然保持固溶体结合形式。三种钛基钎料可实现TZM的高温钎焊,依靠界面固溶体实现冶金结合,经高温长时间热循环后钎焊接头组织性能稳定,发生晶间渗入敏感性低,为TZM的高温应用连接提供理论与试验指导。

Abstract:

The high-temperature vacuum brazing of Titanium-Zirconium-Molybdenum (TZM) alloys was efficiently realized while using the Ti-8.5Si, Ti-33Cr and Ti-30V-3Mo brazing filler metals, respectively. The thermostability of the brazing joint interface after high temperature thermal cycle was studied by SEM, EDS, wettability test and shearing test, etc. And so as to the thermostability of the brazing process. The results showed that, under the technological parameter of 1520℃/6min, both Ti-8.5Si、Ti-33Cr brazing filler metals had good wettability on the surface of TZM alloy, the wetting angle was 10° and 9°, respectively. The spreading area of Ti-8.5Si brazing filler metal was larger than that of the Ti-33Cr brazing filler metal. Under the technological parameter of 1680℃/8min, the Ti-30V-3Mo brazing filler metal had a 5° wetting angle on the surface of the TZM alloy. The (Ti, Mo) solid solution was formed in the interfaces of the Ti-8.5Si/TZM and the Ti-33Cr/TZM brazing joints. The center of the Ti-8.5Si/TZM brazing seam was composed of (Ti, Mo) solid solution and Ti₅Si₃ phase. The center of the Ti-33Cr/TZM brazing seam was composed of (βTi, Cr) solid solution and the αTi + (αTi+αTiCr₂) eutectic. The brazing seam of the Ti-30V-3Mo/TZM joint was consist of (βTi, V) solid solution and the αTi phase, and the boundary zone was consist of (Ti, Mo) solid solution. There all formed solid solutions in the brazing joints to realize the metallurgical bonding between the brazing filler metals and the TZM alloys when using these three kinds of brazing filler metals. The shearing strength of the brazing joints were 135.8MPa (Ti-8.5Si), 132MPa (Ti-33Cr) and 131MPa (Ti-30V-3Mo), respectively. There were no obvious intergranular infiltration and parent metal dissolution phenomena in the Ti-8.5Si/TZM and Ti-33Cr/TZM brazing joints after the 1200℃/60min thermal cycle treatment, the boundary zone was still combined by the solid solution. In the Ti-30V-3Mo/TZM brazing joint after 1550℃/60min thermal cycle, there was one crystalline grain depth intergranular dissolution phenomenon, no obvious parent metal dissolution was observed, and the interface remaining combined by the solid solution. These three kinds of Titanium based brazing filler metals can realize the high-temperature vacuum brazing of the TZM alloy through metallurgical bonding of the interfacial solid solution. The microstructure of the brazing joint after long time high temperature thermal cycle is stable, and the intergranular infiltration sensitively is low. The research of this subject provides theoretical and experimental guidance for the high temperature application connection of the TZM alloy.