GB787665A - Improvements relating to aluminium-base alloys - Google Patents

Abstract

The physical properties and response to heat treatment of Al-base alloys containing 0.2-5 per cent Li are improved by maintaining the Na content of the alloys at not over 0.008 per cent. The alloys may contain other alloying ingredients such as Cu up to 5 per cent, Si up to 5 per cent, Zn up to 10 per cent, Mg up to 10 per cent, Fe up to 3 per cent, Mn up to 3 per cent, Ni up to 3 per cent, Nb up to 0.3 per cent, B up to 0.3 per cent and Ti up to 0.3 per cent, the total proportion of such further alloying ingredients preferably not exceeding 15 per cent. If the Al and Li used in making the alloy have excessively high Na contents, they may be treated separately or together with a flux capable of removing Na. To avoid loss of Li the flux should be one non-reducible by Li, e.g. a flux of LiCl or a mixture of LiCl and LiF. Examples are given of the properties of the alloys as cast, as forged, as extruded and also in the heat treated condition, the heat treatments involving treatment for 24 hours at temperatures from 500-530 DEG C. followed by ageing at temperature from 150-200 DEG C.