US1788751A - Aluminum alloy - Google Patents

Description

Patented Jan. 13, 1931 UNITED STATES, PATENT OFFICE gUGEN STRASSER, OF ROIRSCHACH. SWITZERLAND, ASSIGNOR TO MAX DIETIK EBI, OF

. ZURICH, SWITZERLAND ALUMINUM ALLOY Io Drawing. Application filed February 24, 1927, Serial No. 170,748, and in Germany February 27, 1926.

This invention has reference to aluminum alloys and particularly to alloys of the kind referred to which are adapted for casting purposes, and it is the object of this invention'toproduce an aluminum alloy which is particularly distinguished by great strength, high tensile properties, Brinellhardness and resistance to heat combined with a high degree of density and superior working properties. The composition of the alloy accordin to this invention is such that the alloy will ear considerable additions of zinc without thereby detracting from its valuable mechanical properties, so that by this addition the cost of manufacture may be considerably reduced.

In accordance with this invention I proceed by adding to the aluminum, the aluminum-zinc or to any other aluminum alloy diflicultly melting metals, and particularly such as are adapted to increase the tenacity and viscosity of the final product, these additions being made in the form of a preliminary alloy and preferably in such a manner that this preliminary alloy may be deoxidized by the covering up of the layer of liq uid' metal by a layer of salts suitable for forming a slagwith the metal oxides and becoming dissolved to a large extent by the action of the metal, and by the subsequent addition of a deoxidizing agent.

-In order to produce the valuable properties of the alloy it is for instance suflicient.

to add as much as two percent only of the preliminary alloy which may be composed in a preferred embodiment of copper, nickel and magnesium to a quantity of 98% aluminum and zinc. A very satisfactory alloy'of this kind is composed of 98% aluminum and zinc, 1.8% copper, 0.1% nickel and 0.1% magnesium. As a protecting salt-layer potassium-fiuoride may be used inthe manufacture of the preliminary alloy, and preferably about 3% of the total amount of the preliminary alloy. The manufacture of the alloy may for instance be carried out substantially as follows As the firststep a preliminary alloy is obtained by melting copper and 5% nickel and sprinkling thereupon about 3%fluoride of potassium, KF, after fusion. The potassorbed by the fused'metal. Afterthe salt has been completely liquefied 5% magnesium are added. The magnesium acts at the same timeas a deoxidizing agent, and the portion not consumed thereby, constitutes an ingredient of the alloy. The oxide of magnesium which has been produced by mutual reaction with the oxide originally present in the metallicmass either in solution or in 'the colloidal state, forms a slag with the salt and rises with it to the surface, where it continues to form a slag with the cover of salt. The fused metal is thereby freed from oxides in a manner and to an extent heretofore not known. 2% of the preliminary alloy thus obtained are then added to a supply of 98% aluminum and zinc. As the result an alloy is obtained consisting of 98% aluminum and zinc, 1.8% copper, 0.1% nickel and 0.1%

magnesium. In this alloy up to 18% of zinc and even more zinc may be contained, inasmuch as this ingredient has a favorable in fiuence on the mechanical qualities of the casting to be obtained. I

In order to' full utilize the good qualities of this alloy it is o importance to arrange for a chilling action in the casting of the pieces of casting, and this. chilling should avoid excesses in either direction, so as not to be too strong and not too low, but a kind of medium degree of chilling should be obtained, as occursfor instance in the employment of a mould comprising moulding sand with an admixture of metal in powdered or' granular condition and containing about 6% of water when being used for casting pur poses. A similar action may be produced by means of a dry'mould consisting of-a mass of moulding material containing for instance clayor mixtures of loam, calfs hairs, chopped straw and the like, if this mould after drying is likewise moistened with about 6% of water; also with this dry mould it is of importance that in the manufacture of the moulding mass an admixture is made of metal In case the chilling action has been too high as a result of excessive moisture in the mould the piece of casting may be improved by tempering it for several hours at a tem- 5 perature above the metallurgical point of con- 7 version which is specific to the alloy under" treatment, and by then submitting it to a retarded or prolonged cooling action. In the subsequent aging of the casting a very con- 10 siderable acceleration will be found in the attainment of the most favorable values for the mechanical properties. I wish it to'be understood that the mode of procedure and kind and percentages of in-' gredients herein enumerated are merely stated by Way of exemplification and illustration of the principles of the invention without excluding modifications and changes thereof, except as otherwise contained and stated in V the appended claim.

j Iclaim:

A method of manufacturing an aluminum alloy casting, consisting in making a preliminary alloy ofapproximately 90% copper and 5% nickel, covering the same with a fused layer of potassium-fluoride adaptedto scorify the metal oxides present, adding approximately 5% of magnesium while stirrin and then casting the preliminary alloy; a ding about 2 per cent of this preliminary alloy to aluminum or aluminum-zinc alloy containing up to 18% zinc, casting the same in a mold consisting of a material having a chilling effeet on the alloy, said mold material containing granulated metal and having a water content of about 6%; the aging of the resulting alloy thus taking place during the progress of the process without the necessity of subsequent heattreatment. Y 0 In testimony whereof I afix my signature.

' EUGEN STRASSER.