US2576738A - Gold alloys - Google Patents

Description

Patented Nov. 27, 1951 GOLD ALLOYS Joseph M. Williams, Attleboro Falls, Mass., as-

signor to Metals & Controls Corporation, Attlcboro, Mass., a corporation of Massachusetts No Drawing. Application April 21, 1949, Serial No. 88,905

6 Claims.

This invention relates to alloys, and with respect to certain more specific features, to gold alloys.

Among the several objects of the invention may be noted the provision of a gold alloy which may be used in the manufacture of either gold plated objects or so-called solid gold objects; the provision of a gold alloy which is -character ized by a fine grained structure, which minimizes what is known as orange peel (surface roughness caused by large crystals of metal being forced into relief by mechanical working of the metal) during the manufacture of articles of jewelry from the gold alloy; the provision of a gold alloy which may be used either as solid gold or gold plate which has a high degree of re sistance to tarnish and corrosion factors encoun tered in atmospheric conditions and in perspiration acids, etc.; and the provision of a gold alloy in which the recrystallization temperature of the alloy is at a higher value with resulting improved temper, hardness, and grain size as compared to previously known alloys. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the ingredients and combinations of ingredients, the proportions thereof, and features of composition, which will be exemplified in the products hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the manufacture of plated gold articles of jewelry, the gold plating is often quite thin, with the result that a problem is presented of providing a gold alloy for the plate which will resist abrasion when the article is being used or worn, it being difi'icult to provide a gold alloy with a high degree of wear resistance in a given karat which would have a color acceptable to the trade for that karat. The alloy which is the subject of this invention provides a. metal which, for a given karat and color, has a desired degree of wear resistance.

Furthermore, during the manufacture of articles of jewelry from solid gold or gold plated stock, the material must oftentimes undergo bending or twisting or stretching operations. These operations tend to cause large grains or crystals of the metal to stand out in relief on the surface of the alloy, giving the effect known as orange peel. In the alloy of the present invention, the grain structure is fine and of such nature as to minimize the production of orange peel.

A third, much desired characteristic of a gold iii alloy for the jewelry and allied industries is that of tarnish and corrosion resistance, especially Where the article will come in contact with perspiration and skin acids. This is one of the serious problems of the industry, and one solution for it in the past has been to make the alloy richer in gold content. This is naturally an expensive solution to the problem, due to the high cost of the gold. The alloy of the present invention provides a metal which has a desired high degree of resistance to tarnishing and corrosion without the necessity of increasing the gold content thereof.

In connection with the above mentioned orange peel effect and its minimizing or, in some cases, practical elimination, one of the advantages of the alloy of this invention should be explained further, as follows: During the manufacture of the gold alloy either as solid gold wire or sheet, or as gold plated wire or sheet, the material is generally subjected to several heat treating or annealing operations. Also, during the manufacture of articles from such wire or sheet, the material oftentimes undergoes heat treating operations in whole or in part, such as in soldering, or brazing, or welding, operations, and the temperatures to which the alloy is subjected during such operations often equals or greatly exceeds the normal recrystallization temperature of the alloy.

One of the factors governing the grain size in a metal during and after recrystallization, is the original grain size of the metal. It is also well-known that cold working a metal distorts the original grain shape and sets up stresses therein, which become focal points for nucleation and subsequent new grain formation on recrystallization. If a metal is held at the recrystallization temperature over a long period of time, or is raised to temperatures higher than the recrystallization temperature for shorter periods, large grain growth is promoted. It is desirable, therefore, for the metal to have as high a recrystallization temperature as possible. In the alloy of this invention the temperature at which recrystallization takes place is raised, with the result that the alloy may undergo relatively high temperatures without adversely large crystals being formed. This results in an alloy which may undergo more severe heat treating operations without losing desirable qualities such as hardness, freedom from orange-peel, stiffness, etc, than can many hitherto known alloys.

The gold alloy of the present invention consists basically of gold, copper, iron and nickel. As supplementary ingredients, it may also con- 3 tain one or more of the metals silver, zinc, and cadmium.

The gold content depends upon the desired karat of the gold alloy. The present invention relates principally to alloys within the karat range of8' to 20'; hence the proportion of gold in the alloy, by Weight, may vary from about 33% to about 84%.

The copper content may vary from about 10.7 to about 67%, by Weight, of the alloy, depending m upon the color, hardness, and other qualities de sired of the alloy.

The alloy includes bothiron and nickel, each of these metals being variable in the range .05 to 5%, by weight, the combined total weight of both the iron and nickel not to exceed 5% of the complete gold alloy, by weight. It is this combination of the iron and nickel that acts as the regulator of the grain size in the alloy, and holds it to a, minimum. The preferred amount of each of the iron and nickel is about 1.25% by weight of the alloy.

The remaining metals may make up the balance ofthe alloy. Silver and zinc'help achieve the desired color in the alloy. Cadmium seemsto have the same effect on the alloy as the zinc, and may be substituted therefor. Both the zinc and the cadmium have a stifiening effect on the alloy. The silver affects the malleability or workability of the alloy. Each of the silver, zinc, 30 and cadmium may be in the range of about 2-10% by Weight.

With the exception of the alloys A and B, the following table gives the compositions of several specific alloys that have been made in ac- 35 cordance with the teachings of the present invention. Alloys A and B (prior art alloys) are given primarily for comparative purposes.

Composition in percent by weight Cop- 7 Oad- Melt Karat Gold per Silver Zinc mium Iron Nickel Approx. Alloy Egg? Appearance of a 5 mm. Erichscn Cup 2 3 3 5 meters A 74.0 Very coarse orange peel .090. B 80. 0 Extremely" coarse orange peel C.-. 85. 5 Smooth and fine 010. 014. 70 D 85.5 Very smooth and silky .008 En. 82.0 Coarse .090 F 87.0 Very smooth and silky .008 G. 85. 5 Smooth and fine 010-. 014 H- 75. 5 Coarse .090 I 85. 5 Very smooth and silky 010 Alloy Karat Gold Copper Silver Zinc Iron Nickel K 12 50. O 34. 97 5.53 7.00 1. 25 1. 25 L 14 58. 33 28. 67 4. 50 6. 00 1. 25 1. 25

These alloys K and L show the same desirable qualities, such as hardness, relative freedom from orange peel, and small grain size, which are illustrated in the table for alloys C to I.

In general, the best procedure for making the alloys of the present invention is first tomake a base alloy Xcontaining copper, iron, and nickel; these being so proportioned that when added to the gold. plus the supplementary metals, no 'further copper, iron or nickel additions are required. However, it may be found that some alloyscan be made up more easily by mixing the components all together at the start.

For example, to make alloy D, which is a 10 karat yellow alloy of commercial importance, a first base alloy X is made having about the following composition:

Iron 2.78 Nickel 2.78% Copper Balance Then using alloy X together with gold, silver and zinc, the final alloy is made up as follows:

Percent Base alloy X 45.00 Gold 41.66 Silver 7.34

Zinc 6.0

The eiTect of increasing the iron and nickel content is to produce an alloy having a finer grain structure, greater resistance to Wear and corrosion; and a higher recrystallization temperature, and a pronounced tendency to inhibit grain growth at commonly used heat treating temperatures.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results obtained.

As many changes could be made in the above alloys without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in'a limiting sense.

I claim:

1. A gold alloy composed of gold, about33 to 84%; iron, about .05 to 4.95; nickel, about .05 to 4.95%; at least one metal selected-from the group consisting of silver, .zinc, and cadmium each in an amount in the range of 2-10%; and balance copper but not less than about 10.7%; all by weight with the combinedweight of iron and nickel not exceeding 5%.

2. A gold alloy consisting of about '33 to 84% gold; about .05 to 4.95%.iron; about .05 to 4.95% nickel; about 2 to 10% silver; about 2 to.10% zinc; and balancecopper but not less than about 10.7%; all by Weight, with the combined weight of iron and nickel not exceeding 5%.

3. A'goldalloy consisting or about 33 .to. 84%

gold; about .05 to 4.95% iron; about .05 to 4.95% nickel; about 2 to 10% silver; about 2 to 10% cadmium; and balance copper but not less than about 10.7%; all by weight, with the combined weight of iron and nickel not exceeding 5%.

4. A gold alloy consisting of about 33 to 84% gold; about .05 to 4.95% iron; about .05 to 4.95% nickel; about 2-10% silver; and balance copper but not less than about 10.7%; all by weight, with the combined weight of iron and nickel not exceeding 5%.

5. A gold alloy consistin of about 33 to 84% gold; about .05 to 4.95% iron; about .05 to 4.95% nickel; about 2 to 10% zinc; and balance copper but not less than about 10.7%; all by weight, with the combined weight of iron and nickel not exceeding 5%. y

6. A gold alloy consisting of about 33 to 84% gold; about .05 to 4.95% iron; about .05 to 4.95% nickel; about 2 to 10% cadmium; and balance copper but not less than about 10.7%; all by weight, with the combined weight of iron and nickel not exceeding 5%.

JOSEPH M. WILLIAMS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,042,155 Leach May 26, 1936 2,169,592 Peterson Aug. 15, 1939 2,200,050 Auwarter et a1 May 7, 1940 2,216,495 Loebich Oct. 1, 1940 2,248,100 Loebich July 8, 1941 2,310,231 Goldsmith Feb. 9, 1943 FOREIGN PATENTS Number Country Date 379,149 Germany Aug. 18, 1923 575,257 Germany Apr. 26, 1933 218,138 Switzerland Mar. 16, 1942

Claims (1)

1. A GOLD ALLOY COMPOSED OF GOLD, ABOUT 33 TO 84%; IRON, ABOUT .05 TO 4.95; NICKEL, ABOUT .05 TO 4.95%; AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF SILVER, ZINC, AND CADMIUM EACH IN AN AMOUNT IN THE RANGE OF 2-10%; AND BALANCE COPPER BUT NOT LESS THAN ABOUT 10.7%; ALL BY WEIGHT WITH THE COMBINED WEIGHT OF IRON AND NICKEL NOT EXCEEDING 5%.