INCOLOY® alloy 908 (UNS N09908) is an age-hardenable nickel-iron alloy which exhibits a low coefficient of thermal expansion, high tensile strength, high fracture and impact toughness, fatigue crack growth resistance, good ductility, metallurgical stability and weldability plus sufficient resistance to stress accelerated grain boundary oxygen embrittlement (SAGBO) to permit hot fabrication without cracking. This cobalt-free, low CTE alloy was designed to meet sheathing material requirements for internally cooled Nb3Sn superconductor magnets to be used in prototype fusion reactors at cryogenic operating temperatures of -452°F (-269°C/4°K). With low temperature properties it is excellent for cryogenic applications.