Interaction of tungsten with iron–copper and iron–tin melts

The solubility of tungsten in Fe–Cu and Fe–Sn melts and the growth kinetics of W6Fe7 layer at the tungsten–melt interface at 1200°C are examined. The solubility of tungsten in these melts is well described by the following equations: lgXW = –4.3864 + 8.529XFe (Fe–Cu melt) and lgXW = = –4.544 + 14.293 XFe – 23.583 XFe2 (Fe–Sn melt). The melt composition in the three-phase equilibrium W–W6Co7 melt is established: XFe = 4.1 ∙ 10–3, XW = 4.5 ∙ 10–5, the rest is copper (Fe–Cu melt), XFe = 0.111, XW =5.6 ∙ 10–4, and the rest is tin (Fe–Sn melt). The substantial difference in kFe–Sn > kFe–Cu at the same iron activity aFe is attributed to the impact of admixtures (Cu and Sn) on the growth of the W6Fe7 layer.