TOPHEL-NIAL are nickel-base alloys that were developed to provide industry a type K thermocouple in which each leg possesses an adherent, tenacious, black oxide with high emissivity for rapid temperature response. Its EMF-temperature relation is in accordance with NBS Circular 561. Consequently, TOPHEL-NIAL can be used on any existing instrument calibrated for a type K couple. Its stability of E.M.F. is equivalent, or better, than that of other type K thermocouples. TOPHEL and NIAL are suitable for temperatures up to 23000 F. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on forming, heat treating, and machining. Filing Code: Ni-250. Producer or source: Wilbur B. Driver Company.