Thermodynamic properties of the Fe-Cr-P liquid solution

Abstract

A Knudsen-cell mass spectrometer was used to determine thermodynamic properties of the Fe-Cr-P alloys in the temperature range of 1403 to 1821 K. Concentration of the components varied within the mole-fraction ranges, as follows: Fe, 0.059 to 0.801; Cr, 0.054 to 0.789; and P, 0.048 to 0.318. The isoactivity lines of phosphorous are close to the secants connecting the Fe-P and Cr-P binary sides. Iron and chromium activities decrease regularly as the configuration point moves from the Fe-Cr liquid solution toward the Fe-P and Cr-P melts. The thermodynamic properties have been described, with the associated solution model assuming that binary and ternary complexes exist in the melt.

Investigations of the Dephosphorization of Liquid Iron Solution Containing Chromium and Nickel

“…Depending on the author, the value e P Ni is proposed to be 0, [23] -0.004, [24] and -0.006 [25] ; e P Cr lies between -0.016 and -0.030. [13] In the ternary system Fe-Cr-P, a strong intermolecular reaction of a covalent nature, occurs between Fe and P atoms, as well as between Cr and P. The Fe-Cr solution, however, approaches the ideal with a tendency to positive deviations from Raoult's law. In the liquid state, in the solution Fe-Cr-P, binary complexes can form as follows: FeP, Fe 3 P, Fe 3 P, CrP, Cr 2 P, Cr 3 P, Cr 3 P 2 , and ternary, e.g., FeCrP.…”

“…In the liquid state, in the solution Fe-Cr-P, binary complexes can form as follows: FeP, Fe 3 P, Fe 3 P, CrP, Cr 2 P, Cr 3 P, Cr 3 P 2 , and ternary, e.g., FeCrP. [13] The presence of nickel favors decreasing of the activity of phosphorus in the metal. The marked point (heat 16) deviates from the dependence found for M6.…”

“…THE problem of reducing the phosphorus level in iron solutions containing chromium and nickel has been studied by numerous investigators [1][2][3][4][5][6][7][8][9][10][11][12][13] because chromium steels may be produced using iron ores containing chromium compounds as charge materials. However, in such cases, the problem of removing phosphorus from the metal bath during the refining process arises.…”

Empirical Expression of Phosphorus Solubility in Molten Fe1-yCry Given as Functions of Temperature and Phosphorus Activity

“…Equilibrium composition data for molten (Fe,Cr)P was recently reported by Zaitsev et al 1) based on the experiment using Knudsen effusion technique. They measured activities, a Fe of Fe and a Cr of Cr as well as a P of P, over Fe-Cr-P ternary melt with specified compositions as a function of absolute temperature T. Thus, the data were not presented in form of explicit analytical expression for x in molten Fe 1Ϫy Cr y P x as functions of a P and T for given y.…”

“…Instead, they are presented in form of discrete set of tabulated parameter values in the publication of Zaitsev et al 1) Equilibrium data presented in such discrete format is not readily usable for evaluating the solubility x for given Fe 1Ϫy Cr y melt at arbitrary T under certain a P . Therefore, it would be more convenient to present analytical expression for x as explicit functions of T and a P for specified y in order to take full advantage of the equilibrium solubility data presented for the Fe-Cr-P ternary melt made available by Zaistev et al 1) Purpose of the present work was to derive plausible empirical equations for x in Fe 1Ϫy Cr y P x for given y as functions of a P and T to make the estimation of solubility x easier for Fe 1Ϫy Cr y melt of known composition y under specified T at certain a P .…”