Mössbauer analysis and magnetic properties of Invar Fe–Ni–C and Fe–Ni–Mn–C alloys

Abstract

The saturation magnetization and the hyperfine magnetic field of different f.c.c. Fe-Ni based alloys containing nearby 29 at .% Ni were studied as a function of temperature and for different Carbon and Manganese contents. We have observed abnormal behaviors that are explained in terms of mixed exchange interactions between atomic spins: J NiNi (r i ) < 0, J FeFe (r i ) > 0, J NiFe (r i ) < 0.

Properties of Invar alloy Fe‐30.9 % Ni‐1.23 % C after dispersion of structure by upsetting

“…. There is simple relationship between saturation magnetization ⟨M⟩ and the hyperfine magnetic field H at nuclei of iron atoms σ s · ρ = ⟨M⟩: H = A⟨M⟩ + Bμ Fe (A and B are constants) modified for Invar Fe–Ni and Fe–Ni–C alloys . To reveal changes in H for the studied alloy due to the plastic deformation and taking into consideration the neighbour‐polarization contribution to the hyperfine magnetic field the Mössbauer experiment was conducted and the distribution function of the hyperfine magnetic fields p(H) before and after upsetting was recovered , Fig .…”

“…This distinction is associated with the effect of carbon which increases locally distortion of crystal lattice and deviation of interatomic distances from equilibrium ones. Moreover carbon just as nickel significantly alters the pattern of the hyperfine magnetic fields distribution in Fe–Ni austenite with lower nickel content (29–31%) due to its effect on the interatomic distances and atomic order in substitutional subsystem .…”

“…It was shown in that carbon in Invar fcc Fe–Ni–C alloys plays an important role in both strengthening, stabilizing of austenitic phase and efficiently impacting on thermal expansion . These studies have shown that presence of carbon can substantially reduce the thermal expansion coefficient of austenitic Fe–Ni alloy at much lower concentration of nickel (29–31 wt%) and expand the temperature range of the Invar anomaly.…”

Analysis of Causes and Preventing Ways of Early Workability Loss of Three-Cone Rock Bit Cutters

“…Cones of drill bits are subjected to chemical and thermal treatment [3]. The works [36,37] studied the influence of nickel on the course of diffusion processes in alloys was investigated, which is relevant for the selection of optimal modes of chemical-thermal treatment of nickel-doped steels, which are subjected to carburization during the manufacture of drill bit parts.…”