V. P. Titov

Reactions of tungsten with copper-silicon liquids

A study has been made on the interaction of tungsten with silicon dissolved in liquid copper, which leads to the formation of a silicide layer. The measurements were made at 1200°C with silicon contents in the liquid up to 40 mass %. For silicon concentrations below 10 mass %, no silicide is formed at the tungsten-liquid interface. There is a discussion of the reaction thermodynamics. The results may be used to analyze the liquid-phase sintering of tungsten-copper and molybdenum-copper materials with added silicon.

Interaction of Molybdenum with Cobalt–TiN and Cobalt–Copper Melts

The solubility of molybdenum in Co–Cu and Co–Sn melts and the growth of Mo6Co7layer at the molybdenum–melt interface at 1200°C are examined. The solubility of molybdenum in these melts is well described by the equations: lgCMo= −3.642 + 24.589 ⋅ CCo– 134.787 ⋅ CCo2(Co–Cu melt) and lgCMo= −3.363 + 6.552 ⋅ CCo– 6.284 ⋅ CCo2(Co–Sn melt). The melt composition (in atomic fractions) in the three-phase Mo–Mo6Co7–melt equilibrium is established: CCo= 5.34 ⋅ 10−3, CMo= = 3.05 ⋅ 10−4, the rest being Cu (Co–Cu melt); CCo= 0.176, CMo= 5.7 ⋅ 10−3, the rest being Sn (Co–Sn melt). The substantial difference in growth rate constants in the melts (kCo–Sn>> kCo–Cu) with the same cobalt activity αCois attributed to the impact of admixtures (Cu and Sn) on the growth of the Mo6Co7layer. Data on the solubility of molybdenum in Co–Cu and Co–Sn melts and the growth kinetics of Mo6Co7are obtained for the first time.

Theory and technology of sintering processes, thermal and thermochemical treatment reaction kinetics for interaction of tungsten with copper-zirconium melts

We investigated the growth kinetics of layers of W2Zr phase on tungsten interacting with copper-silicon melts at 1150°C. We determined the limiting value of the zirconium content in the copper melt (40.1 at. %). Below this value, we do not observe the indicated layer. We discuss the mechanism of reactive diffusion in the system and the effect of zirconium additives on the liquid phase sintering of the copper-tungsten materials. We have discovered well-defined differences between the growth rates of the layers on polycrystalline and single-crystal specimens of tungsten.

Kinetics of Reaction Interaction Between Molybdenum and Iron–Tin and Iron–Copper Melts

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: lgCMo = (–3.957 ± 0.176) + (25.77 ± 7.94) XFe –– (143.02 ± 77.92) XFe2 (Fe–Cu melt) and lgCMo = (–2.783 ± 0.011) + (7.563 ± 0.111) XFe –– (10.844 ± 0.245) XFe2 (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, kFe–Sn >> kFe–Cu, at the same iron activity aFe is attributed to the effect of admixtures (Cu and Sn) on the growth of the Mo6Fe7 layer. Data on the solubility of molybdenum in Fe–Cu and Fe–Sn melts and the growth kinetics of Mo6Fe7 in these melts are obtained for the first time.

Growth of WSi2 and W6Co7 layers in contact of tungsten with silicon- and cobalt-containing melts

Results of an experimental study of growth of WSi2 and W6Co7 layers on the interface between tungsten and silicon-containing and cobalt-containing melts of alloys on the basis of copper, tin, and silver are described. The growth of the layers was studied at a temperature of 1200°C in the ranges of concentrations of silicon or cobalt in the melt from those corresponding to saturation of the melt by these elements to those corresponding to three-phase tungsten-compound-melt equilibria. It has been established that the rates of growth of layers of these compounds in different melts (at an identical activity of silicon or cobalt) can differ by several orders of magnitude. An assumption is made that this difference is connected with the presence in the compound of an impurity of the element composing the basis of the melt, which affects the rate of transport of its basic components.

Kinetics of disilicide layer growth at the interface of tungsten with molten copper, silver, and tin saturated with silicon

The kinetics of WS2 layer growth at the interface of tungsten with molten metals saturated with silicon is studied. Research is performed at 1200°C using melts based on copper, silver, and tin. It was established that WSi2 layer growth in these melts obeys a “parabolic” rule but the corresponding growth rate constants differ markedly, i.e., from 3.4·10−11 m2/sec (melt based on copper) to 1.5·10−13 m2/sec (melts based on silver and tin). The reasons for this difference are discussed.