Invar
Invar is an alloy of iron (64%) and nickel (36%) with some carbon and chromium. Due to its small coefficient of thermal expansion (about 10-6 K-1 in length; some formulations have negative CoE) it is used in precision instruments (clocks, physics laboratory devices, seismic creep gauges, shadow-mask frames,[1] valves in motors, etc.) However, it has a propensity to creep.