Alcan International Limited

Ernest P Butler

David J Field

Michael P Thomas

Anthony J Bryant

Rowena R Landham

Katherine-Ann Bassett

An extrusion ingot of an Al-Mg-Si alloy, has substantially all the Mg present in the form of particles having an average diameter of at least 0.1 microns of beta'-phase Mg.sub.2 Si in the substantial absence of bet-phase Mg.sub.2 Si. The ingot may be made by casting an ingot of the alloy, homogenizing the ingot, cooling the homogenized ingot to a holding temperature of 250.degree. C. to 425.degree. C. at a cooling rate of at least 400.degree. C./h, holding the ingot for 0.25 to 3 hours, and cooling. The ingot has improved extrusion properties.

Al-Mg-Si extrusion alloy

A composite sheet comprises a porous inorganic membrane and a microporous inorganic film overlying a surface of the membrane, where the membrane may be an anodic aluminium oxide membrane having an average pore diameter of 5 to 100 nm, and the microporous film is of substantially uniform pore size and substantially free of cracks and pinholes. The film may be formed by applying a colloidal sol of an aluminium alkoxide, or a solution of a polymeric precursor of a titanium oxide, to a surface of the membrane to form thereon a gel layer, and drying and heating the gel to convert it to a microporous inorganic film.

Composite membrane

A composite sheet comprises a porous inorganic membrane and a microporous inorganic film overlying a surface of the membrane, where the membrane may be an anodic aluminum oxide membrane having an average pore diameter of 5 to 100 nm, and the microporous film is of substantially uniform pore size and substantially free of cracks and pinholes. The film may be formed by applying a colloidal sol of an aluminum alkoxide, or a solution of a polymeric precursor of a titanium oxide, to a surface of the membrane to form thereon a gel layer, and drying and heating the gel to convert it to a microporous inorganic film.

An extrusion ingot of an Al-Mg-Si alloy, has substantially all the Mg present in the form of particles having an average diameter of at least 0.1 microns of beta'-phase Mg.sub.2 Si in the substantial absence of beta-phase Mg.sub.2 Si. The ingot may be made by casting an ingot of the alloy, homogenising the ingot, cooling the homogenised ingot to a holding temperature of 250.degree. C. to 425.degree. C. at a cooling rate of at least 400.degree. C./h, holding the ingot for 0.25 to 3 hours, and cooling. The ingot has improved extrusion properties.

Al-Mg-Si extrusion alloy and method

The heat treatment of aluminium alloys having a lithium content in excess of 0.5% is carried out in an atmosphere of carbon dioxide and water vapor, the partial pressure of water vapor being at least 4 torr and more usually 10-50 torr.

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Banbury, United Kingdom

Ernest P Butler