Growth of Aluminium Whiskers by Vapour Condensation

Abstract

WHISKERS of volatile metals such as zinc^1,2 and cadmium^2,3 have been grown by vapour condensation methods; but whiskers of other metals have mostly been produced by chemical reduction^4,5. Aluminium presents particular problems because its compounds are resistant to reduction and because the vapour pressure at its melting point is very small (by extrapolation 1.0 × 10⁻⁴³ mm. mercury). At higher temperatures where there is an appreciable vapour pressure the metal is extremely reactive, and even contact with alumina leads to the formation of a sub-oxide. The work reported here shows that it is nevertheless possible to produce aluminium whiskers by a vapour condensation method using high supersaturations.