I have searched the internet, but I could only find instructions to
solder under a specificatmosphere.
Is there an easy way to tantalum soldering?
Is there an easy way to tantalum soldering?
No, not without very specialized equipment.
Jim
James Binnion
James Binnion Metal Arts
In short, No laser welding is probably the way to go.
Nick Royall
It has to be done in a vacuum setting. Laser weld with an argon
shield…or you could take a nice trip on the next space shuttle 
Bill
Reactive Metals Studio, Inc
Cannot be soldered with normal jewelry equipment. Neither can
Niobium nor Titanium.