Chromium powder separable into 0·0068–μm colloidal and 0·16–μm coarse powder fractions was obtained by reduction of Cr2O3 with Mg vapour in a vacuum furnace. The coarse powder fraction was calculated to contain 8 vol.-% residual MgO plus MgO. Cr2O3 dispersoids, probably suitable for dispersion-strengthening. Other chromium powders, of 0·08–0·60–μm particle size and with oxygen: surface area ratios of ∼0·002 g/m2, were made by reduction of Cr2O3 with Li and Na vapours. Nickel powder, of 1·25–μm particle size and with 0·114% oxygen, was made by reduction of NiO with Li vapour.
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