Thermodynamic activity measurements of the liquid CuGd alloy by high temperature mass spectrometry

Temperature–composition dependence of thermodynamic mixing functions of liquid alloys of copper with rare-earth metals

“…A joint assessment of the experimental data [1, 8,23] for the copperlanthanum system allowed us to find parameters of the model to describe the excess heat capacity [19] with a nearexperimental accuracy. We also reached satisfactory agreement between the experimental mixing enthalpies [14,15] and activities of components [25] in modeling the thermodynamic properties of copper-gadolinium melts. Figure 1 shows results of modeling the thermodynamic mixing functions using data on several ΔH isotherms for the Cu-Ce, Cu-Pr, and Cu-Nd systems.…”

“…This result is not due to a random measurement error since it was confirmed in two studies [1,3], where the mixing enthalpies of copper and scandium were investigated over wide composition ranges. The asymmetric composition dependence of excess thermodynamic functions of mixing in the systems is also indicated by studies focusing on activities of melt components [22][23][24][25]. The minimum values of integral Gibbs energy calculated in these papers also fall into the range of copper-rich alloys at x REM = 0.40.…”

“…This may be associated with decrease in the degree of short-range chemical ordering in melts in the course of their overheating. The indications of the temperature dependence of the thermodynamic activities of components were obtained in [25], where activity of copper in melts with gadolinium was studied in the temperature range 1282-1644 K (Fig. 1).…”

“…The excess heat capacity ex P C Δ was studied in a few papers: Cu-Y [19], Cu-La [19,20], Cu-Ce [19,21], and Cu-Pr, Cu-Nd [19]. The isotherms of thermodynamic activity of copper a Cu were studied for Cu-Y [22], CuLa [23,24], Cu-Gd [25], and Cu-Lu [26] melts. The number of the above-listed references per system corresponds to the number of independent experimental studies.…”

“…At present, the number of publications that represent original experimental information on the thermodynamic properties of Cu-REM melts is close to 30. The studied properties include the partial and integral mixing enthalpies of components [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], high-temperature content of the enthalpy [19] and heat capacity [20,21] of liquid alloys, and activity [22][23][24][25][26] of components. The thermodynamic properties of liquid alloys in sixteen systems, excepting the systems of copper with promethium and terbium, have been experimentally studied to varying extents.…”