Some regularities in the thermochemistry of alloying of rare earths with late 3d-transition metals

The enthalpies of mixing for the liquid Co-Sb alloys are measured by isoperibolic calorimetry at 1600 K over the whole concentration range relative to liquid Sb and undercooled liquid Co. The minimal integral enthalpy of mixing is −6.3 ± 0.6 kJ/ mole at x Co = 0.50. Activity of components, Gibbs energy, and the entropy of mixing are calculated using a short-range ordering model considering CoSb associates formed in molten Co-Sb alloys.

Section: Experimental Techniquementioning

confidence: 99%

“…To find consistent dependences i H Δ for both components over the entire concentration range, the partial α-functions were subjected to an iteration procedure. The calculations were detailed previously in [8].…”

Section: Experimental Techniquementioning

confidence: 99%

Thermal chemistry and short-range order in Co-Sb melts

Иванов

Tedenac

Bulanova

et al. 2007

“…In the last ten years the number of studies of binary alloys of REM with 3d-metals has increased. The first systematic study of the enthalpy of mixing of 3d-metals (Mn, Fe, Co, Ni, Cu) with REM was carried out in [2], and later the enthalpy of mixing was studied for alloys of copper with Eu, Dy, Yb [3], and liquid alloys Co − Dy [4], Co − Ce, and Co − Sm [5]. For all of the test alloys the considerable exothermic effects were established for alloy formation increasing in the REM series from La to Lu.…”

Section: Introductionmentioning

confidence: 99%

Thermochemistry of binary alloys of lanthanum with 3d-transition metals

Березуцкий

Usenko

Иванов

2006

The enthalpy of mixing for liquid binary alloys of lanthanum with 3d-transition metals (Sc, Ti, V, Cr, and Fe) is determined by a calorimetric method within the field of compositions rich in lanthanum. Data for the partial enthalpy of mixing in the La − 3d-metal system with infinite dilution demonstrates a complex relationship of a change in it in the series of 3d-metals connected with gradual filling of the 3d-zone due to alloy formation with lanthanum.

“…The tendency of melts towards glass formation depends to a considerable extent on their thermodynamic properties that determine the advantages of the disordered state (liquid or amorphous) compared with the crystalline state. Features of reaction in binary systems R − d-metal have been considered in publications, for example [1][2][3][4][5]. It has been established that the thermodynamics of intermetallic compound formation for copper with R has not been studied sufficiently.…”

mentioning

confidence: 99%

Thermodynamics of rare earth metal interaction with copper

Sidorko

Goncharuk

2006

The change in thermal and thermodynamic properties along the isoformula series of rare earth metals (R) compounds with copper is analyzed. It is shown that in binary R − Cu systems the maximum thermal effects of formation are observed for the most refractory and congruently melting intermetallic compounds. In the liquid state they are observed at concentrations that are close to the composition of these compounds. It is noted that in contrast to other R scandium on reaction with copper behaves as a d-metal.Alloys and compounds based on rare earth metals (R) exhibit useful chemical and physical properties for practical purposes and often attract attention of researchers and material scientists. Discoveries in the field of hightemperature superconductivity gave rise to interest in studying phase equilibria and thermodynamic properties of ternary systems R − Cu − O and multicomponent systems related to them, within which the binary systems R − Cu are the base. In addition, R − Cu alloys exhibit a good tendency towards a change-over into the amorphous state on cooling a melt at a very high rate (about 10 6 deg/sec). The tendency of melts towards glass formation depends to a considerable extent on their thermodynamic properties that determine the advantages of the disordered state (liquid or amorphous) compared with the crystalline state. Features of reaction in binary systems R − d-metal have been considered in publications, for example [1][2][3][4][5]. It has been established that the thermodynamics of intermetallic compound formation for copper with R has not been studied sufficiently. Of the 89 known compounds forming in binary R − Cu systems the thermodynamics characteristics have been determined experimentally for less than a third. Unfortunately data for the thermodynamic properties of compounds formed in the R − Cu systems have been poorly supplemented, which is connected with experimental difficulties that arise in studying such reactive metals as R.The aim of the present work is to summarize and analyze known data for the structure of phase diagrams for binary R − Cu system, thermodynamic properties of solid and liquid R alloys with copper, to establish the interconnection between the nature of change in thermodynamic functions and the structure of phase diagrams of the corresponding binary system.As is well known, for R due to their particular electronic structure a successive change in physical properties is typical. A similar change of different characteristics, including thermodynamic characteristics, also appears in compounds of R with elements of the periodic system. This makes it possible to establish features of the change in thermodynamic functions of the compounds of copper with R of which the most well known is the enthalpy of formation (Table 1). The composition of R − Cu compounds, the temperature and method of their formation are presented in Table 2 from data in [18].Currently formation of 89 intermetallics in binary R − Cu systems has been established. The system Eu − Cu differs strongly from...