AL 4750 is a low-expansion, high-permeability iron-nickel alloy. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: FE-4. Producer or source: Allegheny Ludlum Corporation. Originally published as Allegheny 4750, February 1954, revised January 2001.