Phase Equilibria in Binary and Ternary Systems with Chemical and Magnetic Ordering

Abstract

Univariant and invariant phase equilibria for systems that display second-order transformations such as chemical and magnetic ordering are arranged consistently aiming to construct complete Scheil's reaction schemes. For this purpose it is assumed that univariant phase boundaries representing second-order (or higher-order) transformations are nothing else than phase fields collapsed into infinitely thin thickness. This implies that second-order transformations can be formally treated like first-order transformations. Adequate notations and representation guidelines are proposed for the Scheil's scheme. Examples are given for binary Al-Fe and ternary Al-Fe-Ta systems using recently obtained thermodynamic descriptions.

New Phase Regions of Ir-Ru-Ti System with Eutectic-Peritectic Transformation

“…There are other ideas to make the reaction scheme more informative. For instance, it is assumed that in ternary systems with second-order transitions corresponding to them univariant ones are degenerated to infinitely narrow phase fields [10]. This assumption means that second-order transition can be formally treated like first-order transition and is described by the Scheil scheme.…”

Atom probe tomography investigation of heterogeneous short-range ordering in the ‘komplex’ phase state (K-state) of Fe–18Al (at.%)

“…The generally accepted assessment of the binary FeeAl phase diagram [22] has been recently re-determined, both experimentally [23] and by thermodynamic calculation [24,25], to better describe the transitions between the chemically disordered A2 phase through to the B2, B32 and D0 3 ordered states, including also ferromagnetic ordering transitions. It is also noted in this system that the development of ordered structures as well as the ordering kinetics have been shown to display differences between coarsegrained and nanocrystalline material [26].…”

“…SRO analysis of the experimental APT data has been carried out using the recently developed generalised multicomponent short-range order (GM-SRO) parameters [66,67]. This new definition is an extension of the pairwise, multicomponent parameter (PM-SRO) developed by de Fontaine [68], which itself has roots in the pairwise [24] and [25]. The dot-dashed line represents the region corresponding to the K-state.…”

The physical chemistry of inorganic materials developed in the studies of V. N. Eremenko’s school: physicochemical analysis and thermodynamics of alloys

“…The need to involve secondorder (and higher) transitions into the Shiloh reaction scheme for a complete description of phase transitions in systems where they occur has been long evident. Nevertheless, this aspect was addressed in detail only in a very recent paper by a combined team from the Department for Physical Chemistry of Inorganic Materials and the Research Center ACCESS e. V. A method is proposed to represent second-order transitions in the Shiloh reaction scheme used in our own studies [8].…”

“…Portion of the vertical section of the Al−Fe−Ta system at 2 at.% Ta isopleth: dashed-and-dotted and dotted lines show second-order transitions (magnetic and chemical ordering, respectively)[8] Ranges of thermodynamically stable quasicrystalline phases in the ternary Al-dM 1 -dM 2 systems with icosahedral (a) and decagonal (b) structures (dM 2 is a d-metal with a more filled d-shell):…”