Alloys and phase equilibria in the Al-Ti-Rh system. I. Solidus surface of the TiRh-Rh-AlRh partial system

The data of metallography, x-ray diffraction, electron microprobe, and differential thermal analyses are used to project the solidus surface of the partial TiRh-Rh-AlRh system onto the concentration triangle for the first time. No ternary compounds are found in this system. It is established that there are four single-phase surfaces corresponding to the rhodium solid solution, phases based on Ti₃Rh₅ and TiRh₃ compounds, and the δ phase (continuous series of solid solutions between isostructural CsCl-type AlRh-based phases and high-temperature modification of the TiRh-based phase). The solidus surface also contains five ruled surfaces bounding two-phase volumes and two isothermal planes that are constituents of invariant four-phase equilibria reached at 1714 and 1675°C, respectively.     

Alloy structures and phase equilibrium diagram of the Hf-Ru-Ir system. II. Solidification of alloys and polythermal sections in the state diagram of the partial system Ru-HfRu-HfIr-Ir

Translated from Poroshkovaya Metallurgiya, No. 2(350), pp. 68–73, February, 1992.     

Alloy behavior and the Sc-Ru-Rh phase diagram. Part 1. Solidus surface in the Ru-ScRu-ScRh-Rh partial system

Data obtained by microstructural, x-ray phase, and microprobe analysis have been used together with measurements of the temperature for the start of melting by the Pirani - Alterthum method to obtain a projection of the solidus surface in the partial Ru-ScRu-ScRh-Rh system on the concentration triangle. It is found that ternary compounds are not formed. The solidus surface is made up of five surfaces for the primary crystallization of solid solutions based on ruthenium and rhodium together with phases based on the compounds ScRu₂, ScRh₃, and the 6 phase (a continuous series of solid solutions between isostructural phases of CsCl type based on ScRu and ScRh), together with seven lineated surfaces, which enclose two phase volumes, and three isothermal areas, which relate to nonvariant four-phase equilibria involving the liquid: L — + 2> + 6 (1650°C), L + + 3> (1640°C) and L + + 3> (1520°C).Materials Science Institute, Ukrainian National Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8, pp. 141147, July–August, 1996.     

Metastable phase equilibria in the lead-tin alloy system: Part II. Thermodynamic modeling

The lattice stability of Sn is reassessed in view of additional pressure-temperature data since the earlier assessment by Kaufman. The metastable phase boundary of the α-Pb phase reported in Part I in connection with available thermochemical data is used to define more accurately the model paraaeters for the stable L, α, β, and metastable α₁-phases. Using these models, the stable phase diagram of Pb−Sn, the metastable extension of the stable phase diagram, and several possible metastable phase diagrams are calculated. Thermodynamic and kinetic criteria are used to discuss the formation of various phases during rapid solidification processes.     

Melting equilibria in the iron-rich corner of the Fe-Ni-Mo system

Isothermal holding tests were carried out in the Fe-Ni-Mo system in the two-phase region between the liquidus (melt) and the solidus (crystal). The δ and γ liquidus surfaces in the iron-rich corner of the Fe-Ni-Fe₃Mo₂-NiMo subsystem, as well as the position of the peritectic line situated between them, could be very accurately established by the experimentally determined isotherms. Based on these results and on the known liquidus lines in the three boundary binary systems, as well as on the known concentration fields of the Fe₃Mo₂-NiMo solid solutions, the melting equilibria could be developed with sufficient accuracy in the entire subsystem.     

Melting equilibria in the iron-rich corner of the Fe-Ni-Cr system

Isothermal holding tests were carried out on the Fe-Ni-Cr system in the two-phase region between the melt and crystal in order to determine the γ and δ liquidus surfaces in the iron-rich corner, to establish the position of the peritectic line running between them, and to compare the results with those contained in relevant literature. The initial contents of the 13 test series were staggered in roughly equal intervals from 29.6% Ni and 12.9% Cr to 18.7% Ni and 28.4% Cr. They were held between the temperatures of 1450 and 1530 °C at intervals of 10 °C for 40 minutes in each case, so that 93 liquidus concentrations and temperatures were determined. Both liquidus surfaces can be described very accurately with corresponding mathematical equations and mathematically intersected in order to determine the course of the peritectic line. The results enable sufficiently accurate development of the melting equilibria of the entire ternary system, building on the basis provided by the known γ and δ liquidus lines of the three binary systems.     

Solidification and phase equilibria in the Fe-C-Cr-NbC system

A solidification model is developed and experimentally checked for Fe-C-Cr-Nb alloys in the white cast irons range. It is based on a partial quaternary Fe-C-Cr-NbC phase diagram and predicts the possible solidification paths for the alloys containing γ, with (Fe,Cr)₇C₃ and NbC as the microconstituents at room temperature. The dendritic γ to massive (Fe,Cr)₇C₃ transition in experimental alloy microstructures with NbC contents up to 22 pet is explained by this model. Thermal analysis is also used to compare the solidification paths and model approach.     

Thermodynamics and phase equilibria in the Al-In-Sb system

As part of a program for determination of the thermodynamic properties of the group III and V alloys and assessment of the phase equilibria, the activities of aluminum in the liquid Al-In-Sb system have been measured using a concentration cell of the type

Application of thermodynamics of heterogeneous phase equilibria to the construction of the Fe-Si-O ternary phase diagram

Based on the thermodynamic principles of phase rule and heterogeneous equilibria, the ternary phase diagram for the system Fe-SiO in the range of temperatures from 1730 to 1200° has been constructed with more attention paid to temperatures above 1515° and towards the iron corner of the diagram. The system is characterized by a region of three liquids above 1730° which reduces to two-liquids regions at lower temperatures. Several three-phase and four-phase reactions occur in this system on cooling, at various temperatures. Near the iron corner a eutectic reaction occurs at a fixed temperature in which delta iron co-precipitates with cristobalite from liquid iron containing silicon and oxygen. At lower temperatures the system is characterized by an invariant reaction involving liquid iron, delta iron, cristobalite and liquid oxide. For oxygen rich melts, solidification terminates on the Fe-0 binary with the monotectic precipitation of delta iron and liquid oxide. This paper was presented at the Centennial Meeting of the AIME Conference, New York, 1971.     

Thermodynamics and phase diagram of the Fe-C system

A critical review of published data provides a fairly accurate knowledge of the thermodynamic properties of all of the phases of the system Fe-C that are stable or metastable at atmospheric pressure. Selected data are shown as tables and equations. A proposed phase diagram differs only slightly from others recently published but has the following features. Peritectic compositions and the α-γ equilibrium are shown to agree with measured values of the activity of iron in the solid and liquid solutions and the thermodynamic properties of pure iron. Of all the reported carbides of iron only two may be studied under equilibrium conditions. The solubilities of cementite and of χ-carbide in α-Fe are deduced from measured equilibria. Both are metastable at all temperatures with respect to graphite and its saturated solution in iron. The χ-carbide becomes more stable than cementite below about 230° Certain published data on ε-carbide permit an estimate of its free energy as a precipitate during the aging process.