Fundamental Research on Infrared Detection

Abstract

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The Fe–Ni system: Thermodynamic modelling assisted by atomistic calculations

“…Zhang et al [39] investigated martensitic FeeNi alloys aged in the 300e450 C temperature range and measured a-Fe and g-(Fe, Ni) FM phase compositions in this range. They did not find experimental evidence of the monotectoid equilibrium at temperature lower than 400 C. Combining the results of previous investigations [28,30,31,39] with new measurements on meteoric samples Yang, Williams and Goldstein [12] concluded that the monotectoid equilibrium should occur at about 400 C with phase compositions of about 6 [28], 40 and 46 at% Ni [39] for a-Fe, g-(Fe,Ni) PM and g-(Fe, Ni) FM , respectively.…”

“…The a-Fe þ g-(Fe,Ni) two-phase field ends at a monotectoid equilibrium g-(Fe,Ni) PM $ a-Fe þ g-(Fe,Ni) FM (where PM refers to a paramagnetic state and FM a ferromagnetic state) first proposed by Nishizawa [29] and subsequently calculated by Chuang et al [30,31], but not observed experimentally.…”

“…-The tricritical point and the miscibility gap between g-(Fe, Ni) PM and g-(Fe,Ni) FM , proposed by [30,31] [76]. -The existence of a low spin paramagnetic phase at about 25e30 at% Ni proposed as an equilibrium phase by [77] is not confirmed, but cannot be definitely excluded.…”

“…With increasing Fe concentration the Curie temperature (T C ) increases up to a maximum of about 610 C at about 66 at% Ni and then decreases [34e38]. In 1986 Chuang et al [30,31] calculated the FeeNi phase diagram by taking into account the magnetic contribution to the Gibbs energy of the Critically assessed FeeNi phase diagram: (a) stable phase equilibria according to [14]; (b) low-temperature stable and metastable equilibria according to [12] with Curie temperature (dash-dotted line), metastable continuation of the miscibility gap (dashed lines), boundary of the spinodal region (dotted lines).…”

“…It is mainly based on experimental results obtained by [28,39,74,75] and by [12] himself, together with thermodynamic calculations by [30,31]. Conclusions by [12] can be summarised as follows.…”