4j36 is an austenitic nickel-iron alloy containing 36% nickel with a thermal expansion rate of almost zero - about one-tenth that of carbon steel - in the temperature range -100°C to 200°C. High strength and toughness retention at low temperatures make it suitable for a variety of low temperature or low expansion applications. The alloy is ideal for areas where dimensional changes due to temperature must be minimal, such as tools for aerospace composites, radios and electronic devices, and structural components in precision equipment such as lasers, measuring equipment, thermostats and cryogenic instruments.