Thermodynamic Study of Liquid Ni&ndash;Cr Alloys Equilibrated with Cr<SUB>2</SUB>O<SUB>3</SUB> by EMF Method

Abstract

Oxygen solubility and chromium activity in Ni-Cr alloys equilibrated with Cr203 were measured by a conventional sampling method and the emf method with stabilized zirconia in the concentration range from 2 to 70 at°%Cr at the temperatures of 1733 to 1833 K. Temperature dependences of oxygen solubility are as follows:Activities of Cr show negative deviations from Raoult's law in the nickel rich region and negative to positive deviations in the middle concentration region at 1783 K. The results werecompared with the literature data.

Bulk and surface properties of liquid Al–Cr and Cr–Ni alloys

“…The curve describing the enthalpy of mixing is asymmetric and exhibits a shallow minimum near the composition that corresponds to the CrNi 2 . The calculated values of a Cr and a Ni are close to the corresponding experimental values [33][34][35] (figure 2). The coupled effect of a size ratio, V Cr /V Ni = 1.033, and the normalized form of the Gibbs free energy of mixing, G M /RT = −0.92, enables a more precise classification of the Cr-Ni system in terms of weakly compound-forming alloys.…”

“…Concerning the Cr-Ni system, the excess Gibbs energy of mixing, G xs M [18,19], the enthalpy of mixing, H M [32] and the activities, a Cr [33] and a Ni [33][34][35], have been used to calculate the interaction energy parameters at T = 1873 K and, expressed in RT units, W = −0.77, W AB = −0.15, W AA = 0 and W BB = −0.005, were obtained. The calculated energy parameter reproduces fairly well all available thermodynamic data including the symmetry of the Gibbs free energy of mixing at the equiatomic composition (figure 2).…”

Solubility of Oxygen in Molten Ni–Cr Alloys in Equilibrium with Silicate Slag System Containing Cr Oxide

“…The authors presume that a probable reason lies in the characteristic of activity of Cr in molten Ni-Cr alloy system. Figures 9(a) and 9(b) show activity of Cr in molten Ni-Cr alloy obtained by Katayama et al 5) in the entire range and that in the molar fraction range of Cr lower than 0.2, respectively. It is obvious at every temperature that activity of Cr is closer to ideal solution in the lower fraction range while it deviates more negatively at the higher range.…”

“…They determined the value of e O(Ni) Cr as − 0.231 + 0.009*[mass% Cr] expressed by the first and second order interaction coefficients. Katayama et al 5) also carried out the experiments quite similar to those by Janke. They measured oxygen potential in the molten Ni-Cr alloys leading to activity of Cr in molten Ni in reference to Raoult's law.…”

“…As for Ni-Cr alloys, work has been carried out by some researchers. [2][3][4][5][6] Janke et al 2) measured oxygen solubility in equilibrium with Cr 2 O 3 phase in Ni-Cr alloys by EMF method. They determined the value of e O(Ni) Cr as − 0.231 + 0.009*[mass% Cr] expressed by the first and second order interaction coefficients.…”