Iron Nickel

Iron Nickel

INVAR: Like other nickel/iron compositions, Invar is a solid solution; that is, it is a single-phase alloy, consisting of around 36% nickel and 64% iron.Invar is used where high dimensional stability is required, such as precision instruments, clocks, seismic creep gauges, television shadow-mask frames,[3]valves in motors, and antimagnetic watches. In land surveying, when first-order (high-precision) elevation leveling is to be performed, the leveling rods used are made of Invar, instead of wood, fiberglass, or other metals.

ELINVAR: Elinvar consists of 59% iron, 36% nickel, and 5% chromium. It is almost nonmagnetic and corrosion resistant.The largest use of Elinvar was in balance springs for mechanical watches and chronometers. A major cause of inaccuracy in watches and clocks was that ordinary steels used in springs lost elasticity slightly as the temperature increased, so the balance wheel would oscillate more slowly back and forth, and the clock would lose time. Chronometers and precision watches required complex temperature-compensated balance wheels for accurate timekeeping. Springs made of Elinvar, and other low temperature coefficient alloys such as Nivarox that followed, were not affected by temperature, so they made the temperature-compensated balance wheel obsolete.

KOVAR: nickel-cobalt ferrous alloy designed to be compatible with the thermal expansion characteristics. The name Kovar is often used as a general term for Fe-Ni alloys.Fe 29%,Ni 17%.