Interaction of tungsten with molten aluminium under conditions of low gravitations

The laws and features of tungsten-liquid aluminium diffusion interaction under the weightlessness conditions realized during the Soyuz-Apollo flight have been studied. It is shown that after a high-temperature annealing a diffusion layer consisting of three phases: WAl4, WAl5, and WAl12 has been formed between the above metals. The analysing revealed that the kinetics of metal interaction and phase precipitation in the layer during flight and under ground conditions was about the same. On the basis of the agreement of equilibrium phase concentrations formed under flight conditions with proper values of the tungsten-aluminium system diagram the absence of the zero-weight condition effect on diffusive phase formation is assumed. The following featrues of tungsten-liquid aluminium interaction under flight conditions have been noted: the presence of thinner than on the Earth WAl5 acicular phase areas with smaller needle stray angles; the WAl12 phase crystal-looking facets. The above features can be associated with the significantly reduced convection in liquid state than it is observed under ground conditions