Silicon rejects both phosphorus and sulphur from the surface and hydrogen cleans the surface from silicon. Sulphur might be present in doped tungsten in various states of bonding and some of these bonds disintegrate in the presence of hydrogen. Aluminium oxide formed by internal oxidation in tungsten can be reduced to solute aluminium and oxygen upon annealing at 2400 K in dry hydrogen or at 3000 K in a vacuum of 10** minus **6 Torr. Internal oxidation and reduction also take place in commercial tungsten wires. The radial distribution of the solutes, due to evaporation during sintering, is in some cases conserved during swaging and drawing, too.
|Number of pages||11|
|Publication status||Published - Jan 1 1978|
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