Nilo 42/ Alloy 42/UNS K94100 Alloy 42 (Nilo 42) is a nickel-iron controlled-expansion alloy containing 42% nickel. Alloy 42 (Nilo 42) has a low and normally constant coefficient of thermal expansion from room temperature to about 300ºC (570ºF). Alloy 42 (Nilo 42) is used for semiconductor lead frames in integrated circuits, bi-metal thermostat strip, thermostat rods, for ceramic-to-metal seals with alumina ceramics, and various glass-to-metal seals such as the core of copper-clad-wire for sealing into glass envelopes of electric bulbs, radio valves, television tubes and fluorescent lights.