Nickel silver

Nickel silver is not a simple thing to weld, as the alloy tends to vaporize zinc and then becomes porous. If you have to weld it, use a process with controlled heat input and a suitable shielding gas, preferably TIG. The heat must be kept low, otherwise you'll burn the alloy and the weld will become brittle. Let the part cool slowly after welding, don't quench it, then the structure remains stable.