Simultaneous magnetic and chemical order-disorder phenomena inNi, FeNi, and
- 1 February 1996
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 53 (5), 2291-2302
- https://doi.org/10.1103/physrevb.53.2291
Abstract
We study the magnetic and chemical order-disorder transitions in face-centered-cubic , FeNi, and Ni, by Monte Carlo (MC) simulations using the Ising approximation. The calculations are done: (1) with magnetic interactions only, assuming fixed preset degrees of chemical order, (2) with chemical interactions only, and (3) with both magnetic and chemical interactions acting simultaneously. As expected and known from measurements, the degree of chemical order is found to have a large influence on the magnetic transitions. On the other hand, although one might expect the effects of magnetism on the chemical ordering processes to be small (because the chemical bond energies are much larger than the magnetic exchange bond energies), one finds that the latter effects are also large. Several new features arise that are not predicted by mean-field theory or MC simulations with chemical interactions only. For example: (1) chemical order can be induced where using chemical interactions only leads to the prediction of no chemical order, (2) chemical segregation can be induced where using chemical interactions only leads to the prediction of no chemical segregation, (3) and Ni are found to have significantly different chemical ordering temperatures where chemical interactions only lead to equal ordering temperatures, (4) chemical ordering temperatures are significantly shifted from their chemical interactions only values, even when the chemical ordering temperature is larger than the magnetic ordering temperature (or Curie point), (5) abrupt steps can occur in the spontaneous magnetization at the chemical ordering temperature, when the latter is smaller than the magnetic ordering temperature, and (6) nonlinear relations arise between the chemical ordering temperature and the usual differential bonding parameter U≡2--, where the ’s are the near-neighbor pair-wise chemical bonds. © 1996 The American Physical Society.
Keywords
This publication has 28 references indexed in Scilit:
- Low-spin γ-FeNi(γLS) proposed as a new mineral in FeNi-bearing meteorites: epitaxial intergrowth of γLS and tetrataenite as a possible equilibrium state at ∼20–40 at% NiJournal of Magnetism and Magnetic Materials, 1995
- Physical basis and break down of hyperfine field distribution analysis in fcc Fe-Ni (5–70 at%Fe)Journal of Magnetism and Magnetic Materials, 1992
- On the invar problemPhysica B: Condensed Matter, 1990
- Reentrant magnetism, antiferromagnetism, and domain wall pinning in nominally ferromagnetic Fe-Ni invarJournal of Magnetism and Magnetic Materials, 1989
- Phase relationships in Fe‐Ni alloys at high pressures and temperaturesJournal of Geophysical Research, 1988
- Magnetic and thermal anomalies of Invar alloysJournal of Applied Physics, 1980
- Invar behaviour in crystalline and amorphous alloysJournal of Magnetism and Magnetic Materials, 1979
- Invar anomaliesJournal of Magnetism and Magnetic Materials, 1979
- Isothermal compression of the alloys of iron up to 300 kilobars at room temperature: Iron-nickel alloysJournal of Geophysical Research, 1968
- The Origin of the `Invar' EffectProceedings of the Physical Society, 1963