I need to build an apparatus in which a spring is used to press two parts together, then the entire apparatus is immersed in liquid nitrogen. I expect the spring to shrink when cooled, of course, but I hope I can find a spring that will contiunue to behave more or less like a spring when cooled to 77K (-196C, or -321F). Any suggestions?
Also, what effect will this sort of thermal cycling (room temp, liquid N2, back to room temp) have on Aluminum, Copper, and Lead? Are there any metals that I should specifically avoid using?