The Magnetovolume Effect due to the Decrease of Local Magnetic Moment in Fe-Ni Invar Alloys

Abstract

The local magnetic moment at the Curie temperature in the 35 at% Ni-Fe alloy retains still a half value of the magnetic moment at 0 K. Taking into consideration this fact, new formulas are proposed, which describe reasonably the phenomena of spontaneous volume magnetostriction and forced volume magnetostriction. The magnetovolume coupling constant determined by the new formulas is approximately 1.2 ×10 -8 cm 6 /emu 2 for Fe-Ni Invar alloys, which is independent of the Ni concentration.