Kovar electrical connectors

We are attempting to join Kovar to Nickel to Copper in the same weld joint. This is the electrical connection of a relay used in an aircraft ignition system. Soldering is not a viable option at this point. The weld consists of a .020"dia. Kovar pin with a copper wire attached via a nickel-200 sleeve which pinches the copper wire between the sleeve and the pin. Presently, we are TIG welding the end of the pin with some success. Some of the pins break off, however. I am told Kovar is austenitic and does not harden. I am worried about the copper, however. The welder blames minor repair welding on the breakage. We need to run an experiment with and without repair welds to see if there is a difference. If I can find a supplier of nickel or Kovar electrical connectors I may consider a switch to soldering. Any input anyone?