TOPHEL Alloy and NIAL Alloy are respectively the positive and negative thermoelements for ISA Type K thermocouples. NICROSIL/NISIL Alloys are respectively the positive and negative thermoelements of ISA Type N thermocouples. Thermocouples of 20 and 19 Alloys have the advantage of freedom from green rot preferential oxidation. This datasheet provides information on composition, physical properties, and tensile properties. Filing Code: Ni-400. Producer or source: Carpenter Technology Corporation.