Experimental Investigation and Thermodynamic Reassessment of the Cu-Fe-Si System

Abstract

Based on a critical evaluation of experimental data available in the literature, the isothermal section at 1023 K of the Cu-Fe-Si system was measured using a combination of X-ray analysis, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analysis, and electroprobe microanalysis (EPMA). In addition, fifteen alloys along two vertical sections at 30 and 70 at. pct Cu were subjected to differential thermal analysis (DTA), in order to provide new phase-transition temperatures. A thermodynamic modeling for the Cu-Fe-Si system was then conducted by considering reliable experimental data from the literature and the present work. All the calculated phase equilibria and thermodynamic properties agree well with the experimental ones. It is noteworthy that a stable liquid miscibility gap appears in the computed ternary phase diagrams, even though it is metastable in the three-boundary binaries. Significant improvements have been made compared with the previous assessments. The presently obtained parameters were also successfully applied to two technical cases in material design.

Thermodynamic Assessment of Chemical and Electrochemical Stability of Iron Silicides

“…This allows to extrapolate this calculated equilibrium line down to the standard temperature. [34,35]; 2calculated according to data of [20] using equations (4), (6) and (8); 3calculated according to data of [23] using equations (4), (18), (20) and 21; 4calculated according to data of [38] using equations (4), (10), (13), (14) and 16; 5calculated according to data of [43] using equations (4), (6) and 7; 6calculated in present study using equations 7, (20), (25) and (27).…”

“…And, finally, the authors of [23] give another set of parameters. They consider formation of FeSi from the elements in their standard reference states at low temperatures: (18). This time, the Gibbs energy of reaction (3) can be gained in the following way: (19), But instead of using Gibbs energy change of reaction (12) offered in [38] and listed in the equation (14), the authors of [23] use the value, obtained from database [47]:…”

“…Iron-silicon alloys can be found in Earth's core [8], they are used in the technology as thin films [9] and nanowires [2,10]. Moreover, many important ternary and multicomponent systems, including Fe -Si binary system, such as Ni -Fe -Si [11], Al -Fe -Si [12 -14], Fe -Mn -Si [15,16], Cu -Fe -Si [17,18], Cr -Fe -Si [19], Fe -Zn -Si [20 -22], Fe -Si -C [23 -26], Fe -Si -O [27,28], Fe -Si -B [29,30], Al -Ca -Fe -Si [31] and others, are of great interest for the researchers. The Fe -Si system-based alloys and compounds can be used as corrosion-resistant materials and coatings.…”

Thermodynamic description of the Mn-Si-Zn system

“…The "L1" and "L2" in the monotectic reaction denote the two counterpart phases of the liquid miscibility gap. This kind of monotectic four-phase reaction is common in some technical alloys, such as in the Al-Mg-Sc [15], Al-Cu-Sn [16], Al-Bi-Zn [17], Cu-Fe-Si [18], Fe-Mg-Si [19], and Fe-Si-Zn [20] systems, and has been widely utilized to attain the specific microstructures of alloy solidification at different cooling rates for technical purposes. In addition, the reaction scheme of the entire Mn-Si-Zn system according to the present work is shown in Figure 6, which can provide a useful guidance for advanced material research together with liquidus projections as shown in Figure 5.…”

Assessment of structure and selected mechanical properties of braze welded joints of copper-lined steel tubes

“…Silicon only shows good solubility in iron, but solubilities of Si in Cu, Cu in Fe and Fe in Cu are limited and, in the Fe-Si-Cu system, two-or three-phase mixtures are mostly present (Fig. 10b) [19]. Figure 10b shows an isothermal cross section of the phase equilibrium diagram Fe-Si-Cu at 750 °C, but it can be supposed that differences of phase constitution at ambient temperature will not be large.…”