US2267299A - Alloy - Google Patents

Description

Patented Dec. 23, 1941 Reginald s.' Dean,

Salt Lake City, Utah, assignor to Chicago Development Company, Chicago, 111., a corporation of Illinois No Drawing. Application June 12, 1940, Serial No. 340,135

4 Claims. (Cl. 75-178) This invention relates to alloys of copper, zinc and manganese and, in particular, is concerned with such alloys for die casting purposes.

The alloys of the present invention contain relatively high proportions of zinc, of the order of 60% to 95% zinc, the balance comprising from about 2% to about 30% copper, and from about 5% to about 38% manganese. Small proportions of other alloying constituents may, in certain cases, be utilized where special characeristics are desired, but, in general, the alloys contain substantially only zinc, copper and manganese, such other elements as are present being introduced only as impurities. It should be pointed out at the outset, however, that, for best results, the manganese employed should be electrolytic manganese or other highly pure manganese containmg. preferably, not more than 0.1% of other metals as impurities, and the copper and zinc should also be of highly pure grade, preferably electrolytic.

Although many of the alloys of the present invention have little or substantially no ductility, nevertheless they possess sufiicient strength to make them of marked value for die casting or other castings for parts which are not subjected to great mechanical stress. In general, the alloys of the present invention possess the advantage, over the zinc-copper-manganese alloys heretotore suggested for die casting purposes, in that they are more fluid and can be cast into more intricate shapes while maintaining accuracy of dimensions. Furthermore, they possess an excellent finish, as cast, are readily machinable and are highly resistant to corrosion.

The alloys of the present invention may be produced in accordance with various procedures,

about 0.1% of metallic impurities, may be used in the production of the alloys in accordance with the present invention, for the best results, as previously noted, electrolytic manganese should be used, both because of the relative read- 2 mess with which the alloys are made in accordbut one suitable and dependable method comprises preparing an alloy of zinc and copper and subsequently adding the manganese in the form of a fairly fine powder. It has been found that if the substantially molten mixture is stirred at a temperature slightly below the boiling point of zinc, a homogeneous alloy is produced. An alternative, and also satisfactory method, comprises initially melting the manganese, preferably in a high frequency induction furnace, alloying the same with the copper, and then adding the zinc at a temperature slightly above the melting point of the manganese-copper alloy. Although, in this latter method, there is a slight volatilization of the zinc, the amount volatilized is so small as to--be disregarded.

While, as previously stated, any manganese of ance with the present invention and also because of the especially satisfactory properties of the resulting alloys. i

y The following are illustrative examples of alloys which may be made in accordance with the present invention. It willbe understood that the proportions of the alloying constituents may vary, Within the range set forth hereinabove, and other (changes may be made without departing from the spirit of the invention as pointed out in the appended claims:

Example! Parts Electrolyti zinc 85 Electrolytic manganese 10 Electrolytic copper 5 Example 2 Parts Electrolytic zinc l Electrolytic manganese 10 Electrolytic copper "L- 10 Example 3 f Parts- Electrolytic zinc 86" Electrolytic manganese 9 Electrolytic copper u r 5 A particularly preferred range of the alloying constituents, falling withinthe broader range set forth hereinabove, is from 75% to zinc. from 5% to 15% copper, and from 8% to 20% manganese, the total of the alloying constituents comprising substantially 100%;

What I claim as new and desire to protect by Letters Patent of the United States is:

1. An alloy suitable for the preparation of die castings having good finish, resistance to atmospheric corrosion, and ease of machinability, said alloy containingfrom in excess of 75% up to about zinc, 2% to 30% copper, and 5% to 38% manganese, the total of said alloying constituents amounting to substantially 2. An alloy suitable for the preparation of die castings having good finish, resistanceto atmospheric corrosion, and ,eose of machinability,

high purity, that is, containing not more than 55 said alloy containing from in excess of 75% up to about 95% 'electrolytic zinc, from 2% to 30% electrolytic vcopper, a}? from 5% to 38% electrolytic manganese havinz a purity of at least to! of said alloyin: constituents nmountinl to 99.9%, the total said alloying constituents substantially 100%.

amountin to substantially 109%. 4. A casting alloy containing about 85% line. 3. A die casting consisting 01 an alloy conabout 5% copper, and about substantially taining from in excess of 75% up to about 85% 5 pure manganese.

zinc, from 5% to copper, and from 8% to REGINALD S. DEAN.

% of a substantially pure manganese, the to-