Is Inconel Alloy 750 the best material for springs operating at high temperatures?
The readily available sizes of Inconel X750 should be considered since there are a number of wire vendors that stock it.
INCONEL alloy X-750 Thermal Properties*
* Material heat-treated 2100°F/3 hr, A.C., + 1550°F/24 hr, A.C., + 1300°F/20 hr, A.C.
Values for thermal expansion, thermal conductivity, specific heat, and diffusivity are from Lucks and Deem and electrical resistivity from tests conducted at Lehigh University.