Anti-Invar properties and magnetic order in fcc Fe–Ni–C alloy

Abstract

78)%C alloys in the varying temperature range 150-293 K and in external magnetic field of 1,5 -5 T were conducted. Low value of the Debye temperature  D = 180 K was estimated using the temperature dependence of the integral intensity of Mössbauer spectra for specified temperature range. The inequality B eff = (0.7÷0.9)B ext was obtained in Mössbauer measurement applying external magnetic field that points to antiferromagnetically coupled Fe atoms, which have a tendency to align their spins perpendicular to B ext . Nano-length-scale magnetic inhomogeneities nearby and far above T C were revealed, which supposedly caused by mixed antiferromagnetically and ferromagnetically coupled Fe atom spins. The anti-Invar behavior of Fe-Ni-C alloy is explained in terms of evolution of magnetic order with changing temperature resulting from thermally varied interspin interaction and decreasing stiffness of interatomic bond.

Effect of Al doping on the magnetic and elastic properties of Fe65Ni35Invar alloys

“…Similarly, varying the composition, such as by decreasing the Ni content, leads to a change in the HS/LS ground-state energy levels, so that after a critical Ni content the material exhibits anti-Invar properties [12,13]. The effect of doping some elements has also been investigated for Invar properties [14][15][16]. Our previous work on elastic modulus properties shows that doping the Invar alloy with Si leads to the occurrence of an additional hexagonal structure next to the face-centered cubic and a decrease in T c [17].…”