Yes, it is possible to coat the nickel with either gold or Pt with sputtering process. The sputtering process does not require heat and working under vacuum condition, it should not affect your nickel structure. I have deposited Pt on Ni before, it works.

The thickness of the nickel is thin, and that causes the problem.

Thank you Yuan, I'll give it a try.

Sputtering and vacuum thermal evaporation both can be done to obtain a coating of Au.