If you provide a description of what you have in mind for the metal we can give you a much better answer. For example, molybdenum is a metal that can withstand very high temperatures (>4000degF), but it is not used widely in a pure form. Besides the metals with very high melting temps noted by EmmanuelTop there are many common metals as nickel, iron, titanium, chromium, etc. that have melting points well above 2000degF. But once again, these metals are normally used as part of an alloy for high temp applications such as fasteners or turbine engine components.
For most high-temp applications, pure metals are alloyed to provide a better combination of mechanical properties, ease of fabrication, etc. NASA did quite a bit of development work with niobium alloys for un-cooled rocket nozzles, and with columbium alloys for high-temp fasteners.
Define "affected" ...
As the above mentioned metals and materials can be used at these temperatures, but they are without a doubt "affected" by this temperature in some way or another
