Electron beam (EB) weldability study of Consil 995-a structural material for RE cavity applications of thin film high temperature superconductors

An investigation of successful joining parameters for the silver alloy Consil 995 in connection with EB welding has been performed. The results have been obtained by metallographic inspection, mechanical testing, X-ray diffraction, and electron microscopy. The changes in material properties due to welding and heat treating are reported and compared to those for niobium. From metallographic and mechanical tests, it is recommended that forming and welding fabrication of Consil 995 be performed prior to oxidation hardening. When welded and oxidized, this alloy shows good strength in the base metal and welded regions. This fits well into the scheme of fabricating accelerating cavities as it allows the forming, joining, and oxidation of the cavities before the high-temperature superconductor film is deposited. It is noted that Consil 995 is readily EB welded. A smoother underbead with less root reinforcement is desired and could be achieved by investigating travel speed and focus parameters.