Thermodynamik fester Fe ‐Ni Legierungen: Massenspektrometrische Bestimmung der thermodynamischen Mischungseffekte und Berechnung des Schmelzdiagramms

Abstract

Thermodynamic investigations on solid Fe‐Ni alloys (f.c.c.‐phase) have been performed by means of a mass spectrometer in combination with a high temperature Knudsen cell unit. The “Algebraic Intensity‐Ratio”‐method (A.I.R.) has been applied for determing the thermodynamic excess functions. The molar excess Gibbs energies GE, the molar heats of mixing HE, and the molar excess entropies SE are negative over the whole range of composition. At 1623 K the minimum value of GE is ‐2350 J/mol (57.6 at % Ni), the minimum value of HE is ‐3950 J/mol (63.6 at % Ni), and the minimum value of SE is ‐1.04 J/mol K (70.2 at % Ni). The thermodynamic activities aj show slight negative deviations from Raoult's law. Using the results of this work, the thermodynamic results from mass spectrometric studies on liquid Fe ‐Ni alloys, and literature data for the enthalpies and heat capacities of Fe and Ni the phase diagram has been redetermined, using a generally applicable procedure for the calculation of the equilibrium compositions of coexisting phases. The applied procedure is based upon the generalized Newton method for the numerical solution of equations.

The system Fe–Ni–Cr: revision of the thermodynamic description

“…As can be seen from Fig. 4 the tie lines as reported in [16] show a distinct better agreement with the experimental data than Lee's assessment using a magnetic fcc solid contribution instead of employing the experimental molar excess Gibbs energies from [10,11]. For discussion of earlier experimental investigations see [10,11].…”

“…Therefore it may be understandable that authors are ignoring the lack of experimental investigations, and produce their own sets of assessed data. But sometimes the lack of incorporated experimental results cannot be explained by this reasoning: e.g., Hillert and Qiu [8] have taken for their assessment of the Fe-Ni-Cr phase diagram the thermodynamic assessment of the binary boundary system Fe-Ni as reported by Xing et al [18] and not of the results of mass spectrometric measurements as reported in the same year for the liquid phase in [10], and for the fcc solid alloys in [11]. Fig.…”

“…3. As carried out in [16] slight modifications (up to 5%) of the results of mass spectrometric measurements both on the liquid [10] and on the fcc solid [11] phase makes possible to determine Fe-Ni phase equilibria curves without involving any binary magnetic correction term. As Fig.…”

In-situ TEM observation of structural changes in nano-crystalline CoCrCuFeNi multicomponent high-entropy alloy (HEA) under fast electron irradiation by high voltage electron microscopy (HVEM)

“…The existence of bcc-based B2-FeCo, fcc-based L1 2 -FeNi 3 , and L1 0 -FeNi can be seen in Co-Cr-Cu-Fe (a), Co-Cr-Fe-Ni (c), and Co-Cu-Fe-Ni (d) alloys systems, where the formation energy of each ordered phases was 5.8 kJ/mol, 8.5 kJ/mol, and 6.7 kJ/mol, respectively. Table 2 summarizes the intermetallic compounds and the bcc and fcc-based ordered phases reported in the binary phase diagrams of Co-Cr [25], Co-Cu [26], Co-Fe [27], Co-Ni [28,29], Cr-Cu [30,31], Cr-Fe [32], Cr-Ni [33,34], Cu-Fe [35,36], Cu-Ni [37], and Fe-Ni [38][39][40] It is well-known that various intermetallic compounds and ordered phases transform to a disordered solid solution and/or an amorphous phase under MeV electron irradiation. These phases with low phase stability against irradiation cannot appear from multicomponent solid solution phases under irradiation.…”

Computer-aided thermodynamics of liquid ternary Fe–Ni–Co alloys by Knudsen cell mass spectrometry

“…(6) and (7) yields the required best fit formula. For liquid Fe-Ni-Co alloys, all three binary boundary systems are already investigated mass-spectrometrically [2,6,7], and the resultant molar excess Gibbs energies have been used successfully for the calculations of the binary phase diagrams [6,8,9]. Using the TAP-parameters as summarized in Table 1 the regression problem is, therefore, reduced to the adjusting of the ternary interaction parameters t C G n , and the ternary calibration constant t C G 0 (T) only:…”