Etude par effet mössbauer de l'ordre dans un alliage Fe-Ni 50-50 irradié par des neutrons ou des électrons

Kinetics of tetrataenite disordering

“…In nature, tetrataenite is found only in iron-nickel metals in meteorites that experienced slow cooling. It is noteworthy that tetrataenite is the natural analog of synthetic ordered FeNi, superstructure L1 0 , which has been produced in 1962 by neutron irradiation of Fe 50 Ni 50 alloys [6,7].…”

Theoretical investigation of Mössbauer hyperfine interactions in ordered FeNi and disordered Fe–Ni alloys

“…The value of the quadrupole shift ɛ in 57 Fe obtained from the calculations is +0.35 mm/s. The magnetic hyperfine field at the Fe nucleus obtained was −241 kOe (perpendicular to the layers) and −262 kOe (parallel); these values may be compared to −288 kOe and −327 kOe obtained experimentally [5]. The difference between the values of parallel and perpendicular HF is seen to be due mainly to the rather large contribution from the electron spin-dipolar hyperfine field (also calculated here), originating from non-negligible spin-density anisotropy.…”

“…At low Ni concentrations, an antiferromagnetic (AFM) phase has been characterized at low temperatures, which is present in meteorites [2] and may also be obtained by synthetic means [3]. An ordered form of Fe-Ni 50-50 named tetrataenite is also found in meteorites [4], and may be obtained in the laboratory by irradiation of the disordered 50-50 alloy with neutrons or electrons [5].…”

Fe/Ni Cluster Hybrid Material Produced by Double Glow Discharge Sources

“…17) When they collide with each other on a substrate, Fe and Ni clusters are neither fragmented nor coalesced at interfaces: Fe and Ni clusters randomly coexist on the substrate. 34) Many phase diagrams reported for Fe 1ÀX Ni X alloys to this day clearly indicate that Fe 1ÀX Ni X alloys are classified into an miscible system: 18,[35][36][37][38][39][40][41][42] bcc Fe-rich solid solution, AuCu 3 -type ordered FeNi 3 and fcc Ni-rich solid solution are the ground state structures, while Cu 3 Au-type ordered Fe 3 Ni and CuAu-type ordered FeNi have been obtained in meteorites, fine particles and neutron-or electron-irradiated specimens. On the contrary, the present Fe/Ni nano-hybrid material is a nano-scale heterogeneous mixture of bcc Fe and fcc Ni grains.…”