KINETICS OF REACTION INTERACTION BETWEEN MOLYBDENUM AND IRON–TIN AND IRON–COPPER MELTS

Abstract

The solubility of molybdenum in Fe–Cu and Fe–Sn melts and the growth kinetics of Mo₆Fe₇ layer at the molybdenum–melt interface at 1200 °C are examined. The solubility of molybdenum in these melts is well described by the following equations: lgС_Мo = (–3.957 ±  0.176) + (25.77 ± 7.94) Х_Fe – (143.02 ± 77.92) Х_Fe ² (Fe–Cu melt) and lgС_Мo = (–2.783 ±  0.011) + (7.563 ± 0.111) Х_Fe – (10.844 ± 0.245) Х_Fe² (Fe–Sn melt). The melt composition (atomic fractions) in the three-phase Mo–Mo₆Fe₇–melt equilibrium is established: 6.4 · 10^–3 Fe, 1.64 · 10^–4 Mo, and Cu being the rest (Fe–Cu melt); 0.046 Fe, 3.48 · 10^–3 Mo, and Sn being the rest (Fe–Sn melt). The substantial difference between the growth rate constants in the melts, k_Fe–Sn >> k_Fe–Cu, at the same iron activity αFe is attributed to the effect of admixtures (Cu and Sn) on the growth of the Mo₆Fe₇ layer. Information on the solubility of molybdenum in Fe–Cu and Fe–Sn melts and the growth kinetics of Mo₆Fe₇ in these melts is obtained for the first time.