| 摘要 |
1506476 Composite casting E I DU PONT DE NEMOURS & CO 11 Nov 1975 [11 Nov 1974] 46590/75 Heading B3F [Also in Division E1] A fibre-reinforced aluminium composite comprises from 10 to 80 volume per cent of polycrystalline alumina fibres which have been caused to react with an aluminium alloy containing from 1 to 8% by weight of lithium, preferably by infiltration in a mould at a temperature of from 25 to 100‹ C. above the melting point of the alloy for a time which is less than 15 minutes, such that a reaction sheath containing lithium is formed on each fibre, the aluminium alloy being then cooled to form a matrix containing from 0À5 to 5À5 weight per cent of lithium. The aluminium alloy contains at least 60% by weight of aluminium, preferably at least 90%, and the fibres are present in an amount of from 15 to 70 volume per cent, preferably 30 to 60 volume per cent. The fibres may be either in the form of continuous filaments or discontinuous fibres having a length of at least 3 mm., the latter being either randomly oriented or aligned. The fibres contain at least 60% by weight of aluminium oxide, preferably at least 80%, the most preferred fibres containing at least 95% by weight aluminium oxide. The preferred average diameter of the fibres is from 15 to 30 Á. Other oxides may be present in the fibres in small amounts. The matrix material may be alloyed with additional elements, e.g. copper, iron, magnesium, manganese, nickel, silicon, tin, zinc and/or titanium. and may also contain in an amount not exceeding 1% by weight, beryllium, bismuth, boron, cadmium, calcium, chromium, gallium, lead, sodium, strontium, vanadium and/or zirconium. |
