Lattice parameter and magnetic moment in 3d transition metal alloys: The origin of invar effects

A close relation between the lattice parameter a and magnetic moment μ was found in alloys containing 3d transition metals. The relation can be described by a simple equation: . In Fe-Ni alloys, the magnetic term persists above Tc in the nickel rich region and decreases with temperature in the Invar region. This fact is interpreted as meaning that in the nickel rich region, localized atomic moments persist above Tc, while in the Invar region, they collapse above Tc. Many anomalous properties of the Invar alloys are explained as a result of the collapse of localized moments.