US1975376A - Alloy - Google Patents

Description

Patented Oct. 2, 1934 6 UNITED. STATES PATENT OFFICE ALLOY Georg Schichtel, llobriaeh on Millstattersee,

Austria, assignm- American Magnesium Metals Corporation, Pittsburgh, Pa., a corporation of Delaware No Drawing.

Original application February 14,

1933, Serial No. 656,765. Divided and this application August 22, 1933, Serial No. 686,320

In Austria February 19, 1932 3 Claims.

This application is a division of my prior application Serial No. 656,! filed February v14, 1933.

The present improved alloy 'is one in which magnesium is the predominant element, the primary object being to develop an alloy that will possess the characteristic low specific gravity which is obtained by the use of magnesium in ex- .cess of 80 per cent while such alloy will be characterized by higher resistance to corrosion and at the same time will have a higher strength than the known alloys of this kind. I

The known alloys in use containing generally more than 85% magnesium and as principal additional ingredient aluminum or zinc or both of these ingredients, other constituents such as manganese being presentin relatively small amounts, do not exhibit a'suflicientresistance to corrosion by water or even by damp air, and cannot be used at all when in continuous contact with sea-water. Various attempts have been made to render the surfaces of these metals more resistant by applying coatings, but such attempts failed since corrosion often takes place to-an increased extent when the superficial protective layer is damaged.

The object of the invention is attained by the addition of further additional metals to the alloys, namely antimony or bismuth or both of these metals amounting in general to not less than 0,05% and not more than 2% of the total.

The most diverse alloys of the kind referred to containing antimony or bismuth have proved distinctly superior, when exposed to the action of a 3% solution of common salt, to alloys of the same kind which do not contain antimony or bismuth; whilst the alloys containing antimony or bismuth showed an almost unaltered surface, the samples devoid of antimony or bismuth were strongly corroded on carrying out the comparative tests.

In general the lower limit of efliciency is given by additions of 0,05%, and it is preferable not to exceed the upper limit of 2%.

From their position in the electrochemical series antimony and bismuth are more valuable hitherto in use (electron, Dow-metal) have a comparatively small strength, this constitutes a further advance of considerable importance, the more so as the specific gravity of the alloys is scarcely increased to any perceptible extent by.

the small amount of the added metals.

Furthermore, the" alloys according to the invention show in comparison with similarly composed known electron alloys an increase of the permanent impact strength by 50%.

The alloys may be used as cast alloys or mechanically worked alloys and may be improved by thermal treatments.

containingafrom about 80% to 98.8 per cent of magnesium, zinc in an amount between about 1 per cent to about 20%, manganese in an amount of from about 0,12% to 2 per cent and subject to corrosion, this alloy being rendered more resistant against corrosion by the addition of at least one metal of the group consisting of antimony and bismuth in an amount from 0,05 to 2%. v

2. A low specific gravity magnesium-base alloy consisting of from about 86% to 98,8% of magnesium, from about 1 to 10% of zinc, from about 0,15 to 2% of manganese, and from about 0,05 to 2% of at least one metal of the group consisting of antimony and bismuth. I

3. A low specific gravity magnesium-base alloy consistingof from about 86 to 98,8% of magnesium, from about 1 to about 10% of zinc, from