Mössbauer and SANS Studies of Anti‐Invar Fe‐Ni‐C Alloy under Magnetic Field

Anti‐Invar effect in the f.c.c.‐Fe‐25.3%Ni‐C alloy was revealed, i.e., enhanced thermal expansion coefficient (TEC) (∼20×10−6 K−1) which was accompanied by almost temperature‐insensitive behavior in a temperature range of 122–525 K that was considerably expanded to the low temperature range due to alloying with carbon. The Mossbauer and small‐angle neutron scattering (SANS) experiments with the varying temperature and in an external magnetic field of 1.5–5 T have revealed an existence of inhomogeneous magnetic order in anti‐Invar alloy below and above the magnetic transition point. The anti‐Invar behavior correlates with the thermally induced change in the magnetic order and interspin interaction.