That's too general of a question. The part exposed to the most heat is made out of inconel. Some newer turbines use titanium aluminide. Both are excellent under extended high temperature. You can google those and check the properties. If the turbo is fed a fresh supply of clean oil it will tolerate the heat for extended periods. Some turbos use water cooled bearing housings to help prevent carbonization of oil on the turbine shaft and bearing housing. For application where the engine will be loaded for extended periods oil temperate must be maintained with extra coolers.