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An alloy (64% iron-36% nickel) that exhibits almost no thermal expansion over the temperature range of -50 to 150°C (-58 to 302°F).



an iron-based alloy containing 36 percent nickel. It was first made in France in 1896 by C. Guillaume. It has a low coefficient of thermal expansion (1.5 X 10−6 1/°C at temperatures from—80° to 100°C). Its low thermal expansion is explained by the fact that the magnetostrictive reduction in volume during heating compensates for thermal expansion. Invar is used for making geodetic wires and tapes, rulers, parts for measuring and monitoring instruments, and other items. Its melting point is 1430°C and its strength, about 490 MN/m2(49 kgf/mm2). Invar is subjected to cold plastic deformation with subsequent low-temperature heat treatment to increase its strength. After polishing, the alloy becomes corrosion-resistant under atmospheric conditions; protective coatings are applied to articles made of the alloy that are going to be used in hostile environments. Varieties of Invar are superinvar, an alloy with an extremely low coefficient of thermal expansion (less than 1 X 10−6 1/°C) that contains 64 percent iron, 32 percent nickel, and 4 percent cobalt, and stainless invar, an alloy that contains 54 percent cobalt, 37 percent iron, and 9 percent chromium.

References in periodicals archive ?
The use of AFP, invar tooling and longitudinally incorporated omega (like the Greek letter [OMEGA]) stiffeners, more traditionally called hat stiffeners, are also common between the programs.
INVAR Technologies is a boutique managed IT firm serving clients in the New York tri-state area.
Hanif Abbasi, Chairman Planning and Development, Secretary Specialized Health and Medical Education, head of Rawalpindi Institute of Cardiology Major Gen (Retd) Azhar Kiyani besides President INVAR Global Health Alexander Razinski attended the meeting.
Alexander Razinski, Chairman and Peter Strouzas, Research & Development Manager of M/s Invar International Holding, Inc.
Citing sources in the Indian government, local media earlier reported that India would buy 10,000 Invar missiles from Russian manufacturers and that a further 15,000 missiles will be manufactured under license in India.
The skin consists of a thermal or plasma spray coating such as Invar metal on a sealed surface.
Altogether 23 km of levelling lines were measured using Topcon DL-101C precise digital level and invar rod.
Replace outdated and expensive processes with MIT[TM]--Kovar, Invar, HiMu80, FeNi and Stainless Steels
Highlighted products will include Invar waveguide, thin wall aluminum waveguide, and seamless flexible waveguide.
La cancelacion de los contratos PT 716 y PT 717, firmados por la Organizacion de Energia Atomica de Iran y la empresa estatal argentina INVAR ocurrio el 27 de mayo de 1992, durante el mandato de Carlos Saul Menem.
Es de suponer que la prevencion conductual y cognitiva de esa patologia en la poblacion afectada pase por fomentar la capacidad de afrontamiento, o sea, la resiliencia (Lamas y Lara, 2002; Invar, 2007; Quintana, Montgomery y Malaver, 2009).
He dubbed the material an "Invar" alloy-because the metals are "invariant" when heated, such that the length of a piece of Invar metal does not change as its temperature is increased, as do normal metals.