Creating, probing and confirming tetragonality in bulk FeNi alloys

Ab initio calculations of the phase behavior and subsequent magnetostriction of Fe1−xGax within the disordered local moment picture

“…It may therefore be possible to further enhance magnetostrictive properties by fine tuning the annealing process, for example via the application of external magnetic fields. 57…”

Discovery and Implications of Hidden Atomic-Scale Structure in a Metallic Meteorite

“…To the best of our knowledge, this is the first report of a tetragonal Ni-poor phase in the Fe−Ni system, although recently the synthesis of tetragonal, nominally equiatomic FeNi has been confirmed. 8,22 A relatively big, 4 nm-diameter Ni-poor precipitate, adjacent to a Ni-rich lamella, Figure 3d, is characterized by a strain field as revealed by geometric phase analysis based on Fourier transformation of a high-resolution STEM image as shown in Figure 3e,f. This region, which contains two dislocations and a corresponding strain at the phase boundary (Figure 3e), is consistent with the interpretation of nanoscale decomposition of the metastable tetrataenite phase through precipitation of Ni-poor phases with either cubic A2 (coarse kamacite precipitates) or tetragonal A6 (utrafine precipitates) crystal structures and a lamellar Ni-rich L1 2 -type phase.…”

“…Such conditions can permit the formation of tetrataenite (designation L1 0 , AuCu-I prototype structure) which is extremely difficult to synthesize , in macroscopic quantities suitable for technological applications. Tetrataenite’s alternating layers of Fe and Ni atoms are stacked parallel to the tetragonal c axis to form a superlattice that donates impressive technical magnetic properties . Tetrataenite is not documented in the conventional Fe–Ni binary phase diagram but may be found in meteoritical phase diagrams ,− containing a complex set of ferromagnetic phases ,, that are, by convention, designated by their Ni content.…”

Discovery and implications of hidden atomic-scale structure in a metallic meteorite

“…To the best of our knowledge, this is the first report of a tetragonal Ni-poor phase in the Fe-Ni system, although recently the synthesis of tetragonal, nominally equiatomic FeNi has been confirmed. 8,22 A relatively big, 4-nm-diameter Ni-poor precipitate, adjacent to a Ni-rich lamella, Fig. 3d, is characterized by a strain field as revealed by geometric phase analysis based on Fourier transformation of a high-resolution STEM image as shown in Figure 3e,f.…”

“…6,7 Tetrataenite's alternating layers of Fe and Ni atoms are stacked parallel to the tetragonal c axis to form a superlattice that donates impressive technical magnetic properties. 8 Tetrataenite is not documented in conventional Fe-Ni binary phase diagram 9 but may be found in meteoritical phase diagrams 4,[10][11][12] containing a complex set of ferromagnetic phases 4,13,14 that are, by convention, designated by their Ni content. The L1 0 phase of FeNi forms during cooling from disordered face-centered cubic (fcc, designation A1) Ni-rich taenite.…”