Meteorites and Thermodynamic Equilibrium in f.c.c. Iron-Nickel Alloys (25-50% Ni)

Mossbauer spectroscopy and X-ray investigations show that taenite (f.c.c. iron-nickel alloy) in meteorites generally has decomposed into an ordered phase FeNi with the L10 structure and a disordered f.c.c. iron-nickel alloy containing less than 25% of Ni. The two phases have the same bravais lattice, i.e., they form a pseudo monocrystal. The decomposition is discussed in terms of Fe-Ni phase diagram.