US2306592A - Beryllium alloy - Google Patents

Description

Patented Dec. 2 9, 1942 UNITED STATES PATENT. OFFICE BEBYLLIUM ALLOY Gerard E. Claussen, Springdale,

to Machlett Laboratories Incorp rated,

Conm, assignor Springdaie, Conn., a corporation of Connecticut No Drawing. Application Serial No. 400,5

August 12,1041,

1t Claims. (cl. -150) This invention relates to alloys of high beryllium content and is concerned more particularly with a novel alloy of the kind specified and sheets,

. beryllium has heretofore had only a limited application in the arts.

The present invention is directed to the provision of a novel alloy which has substantially the same desirable physical characteristics as beryllium, but is much more malleable and ductile so that under suitable conditions, it may be readily worked into forms suitable for practical use.

Theinvention is based upon the discovery that ingots of beryllium, even though produced by phere. Preferably, the melting is carried on under a high vacuum, of the order of 0.001 mm. of mercury, and by high frequency currents induced in the metal by means of a coil surrounding the vacuum vessel and supplied withhigh frequency energy. In the melting operation, the magnesium is evaporated oil and most or all of the other impurities are thrown out of the molten mass in the crucible. 1

The ingot of purified beryllium thus formed is melted by high frequency currentsa second time and this operation is again carried on with metal out of contact with a reactive atmosphere and melting the metal in a vacuum, contains films which appear to be made of an impurity. Those films form the surfaces of failure when hot rolling is attempted and seem to separate masses of metal, which would otherwise be workable while hot. As each individual lump of beryllium is covered with an exceedingly thin surface film of oxide, it seems probable that, when the lumps are melted preliminary to the formation of an ingot,

the films of beryllium oxide become trapped within the latter and that the films found within the ingots are made of beryllium oxide.

According to the inventio the difilculties arising from the presence of the films are overcome by adding to the beryllium prior to the melting thereof a small quantity of an agent which is capable of rendering the impurity ineffective to embrittle the beryllium. Titanium is an example of an agent that may be employed for the purpose and when a small quantity of that metal is melted with beryllium, there occurs a reaction evidenced by the evolution of considerable heat. The resulting material is substantially free of films and, although it is brittle in the cold state. it may be readily worked at moderately elevated temperatures.

In the production of the new product, the starting material is a commercial grade of beryllium available on the market in the form of lumps about an inch or so in diameter. This material contains some slag inclusions and a considerable percentage of magnesium. Also there are other impurities, for example, aluminum, iron, and calcium, present in very much smaller amounts. The beryllium is first formed into an ingot and, for this purpose, the lumps,of the metal are placedwithin a crucible of beryllium oxide and melted out. of contact with areactive atmospreferably under high vacuum. A beryllium oxide mold of the self-pouring type is preferred and such a mold is somewhat similar to a funnel in that the main body thereof is of generally cylindrical section and its upper portion is of considerably larger diameter. The beryllium is placed in the upper portion of the mold and, when melted, runs down into the cylindrical portion, the I shape of the'mold eliminating piping.

A small quantity of the agent which is to render harmless the impurity in the beryllium is added to the material to be remelted and the agent may be in the form of small granules which should be placed somewhere in the mold where they will come in contact with the beryllium. Thus, the granules may be placed within cavities in the beryllium ingot itself. The amount of the agent employed should not be less than about A;% and should not exceed 2% by weight of the beryllium, and when titanium is used, the best results are obtained when the amount of titanium varies from 34% to by weight of the beryllium. When present in such small percentages in the liquid alloy, the titanium is soluble near the melting point of beryllium. When the beryllium and titanium are heated, an exothermic reaction occurs and the reaction starts before actual melting of the beryllium takes place and continues for some time, during which the metals are melted and flow down into the cylindrical portion of the mold. In the reaction, the titaniing the embrittling films and renders the impurity harmless. On the assumption that the films are formed of beryllium oxide, the titanium apparently reduces that compound within the melt to beryllium with the probable resultant formation of an oxide of titanium and the possible formation of unusual compounds, such as substantially free of films. The titanium does not appear to attack the beryllium oxide crucible but seems to have a selective action on the impurities present in the molten beryllium metal. Whatever the action may be, the observed fact is that the films disappear from the lower portion of the ingot, leaving it homogeneous in structure and relatively bright on its surface, whereas the upper part of the ingot contains an oxide surface film giving it a somewhat tarnished appearance. If an excessive amount of titanium is used, the ingot does not have desirable working properties and it is, therefore, evident that the amount of titanium to be employed is that which will be suflicient to react with the impurity that is present within the ingot and little, if any, more than that amount.

The alloy high in beryllium produced by the method above described has all of the desirable properties of pure beryllium and, in addition, is workable at temperatures below red heat and oi the order of 500 C. The material maybe rolled by successive passes into thin sheets less than .005" in thickness and vacuum-tight so that they may be used as X-ray windows, and, in addition, the material may behot forged into curved plates and drawn into cups.

In working the material, it is'preierably protected against strong oxidation and, for this purpose, a ortion of the lower part of the ingot produced in the second melt is removed and placed between protective sheets which may be of nickel or stainless steel, for example. These sheets are preferably crimped along the edges so that the piece of beryllium alloy between them -is substantially out of contact with the air. The

sheets with the piece of alloy between them are then raised to the desired temperature and subjected to the desired working operations.

Instead of using titanium as the agent which reacts with the impurity which would otherwise embrittle the beryllium, zirconium may be used. Its action appears to be the same as that of the titanium and correspondingly small quantities may be employed to obtain the desired result.

In the foregoing, I have described the melting operations as being carried on with the metals out ofcontact with a reactive atmosphere. Melt ing under. vacuum is perhaps the most convenient method of thus protecting the metals against oxidation but other expedients may be used, such as use of a protective atmosphere or possibly of I claim:

1. An alloy which consists of beryllium in excess of 98%, a trace of oxygen, and the remainder of a member taken from the class made up of titanium and zirconium which has chemically combined with at least a part of the oxygen.

2. An alloy which consists of in excess of 98% I beryllium, from to less than 2% of a member of the class made up of titanium andzirconium, and a trace of oxygen, at least part of the oxygen being chemically combined with said member of said class.

3. An alloy which'consists of in excess of 98% of beryllium, from /4% to of a member of the class made up of titanium and zirconium, and a trace of oxygen, at least part of the oxygen being in chemical combination with said member of said class.

, 4. An alloy which consists oi in excess of 98% beryllium, not to exceed 2% of titanium, and a trace of oxygen, at least part of the oxygen being in chemical combination with the titanium.

5. An alloy which consists of in excess of 98% beryllium, from to not more than 2% of titanium, and-a trace of oxygen, at least part of the oxygen being chemlcallycombined with the titanium.

6. An alloy which consists of in excess of 98% of beryllium, from to of titanium, and a trace of oxygen, at least part of the oxygen being in chemical combination with the titanium.

7. An alloy which consists of in excess of 98% beryllium, not to exceed 2% of zirconium, and a trace of oxygen, at least part of the oxygen being in chemical combination with the zirconium.

8. An alloy which consists of in excess of 98% beryllium, from to not more than 2% or zirconium, and a trace of oxygen, at least part of the oxygen being chemically combined with the zirconium.

9. An alloy which consists of in excess of 98% of beryllium, from to of zirconium, and a trace of oxygen, at least part of the oxygen being in chemical combination with, the zirconium.

10. An alloy which consists of beryllium in excess oi 98%, traces of impurities, and from to 2% of a member-o1 the class made up or titanium and zirconium, the alloy having substantially the characteristics of beryllium except for having such malleability as to permit it to be hot worked.

11. An alloy which consists of beryllium in excess of 98%, traces of impurities, and from to /2% of a member 01' the class made up of titanium and zirconium, the alloyhaving substantially the characteristics of beryllium except for having such malleability as to permit it to be hot worked. i

12. A rolled vacuum-tight sheet of a material consisting of more than 98% beryllium, from to 2% of a member or the class made up of titan-. ium and zirconium, and traces oi impurities;

13. A rolled vacuum-tight sheet less than .005" thick made of a material consisting of more than 98% beryllium, from to 2% of a member of the class made up of titanium and zirconium, and traces of impurities.

14. A vacuum-tight X-ray window comprising a thin rolled sheet of an alloy comprising beryllium in excess of 98%, and from to 2% of a member of the class made up of titanium and zirconium, the window, being substantially as pervious to X-rays as one made of beryllium. 15. An alloy containing from about to about 2% of a member of the class made up of titanium and zirconium, substantially the balance of the alloy being beryllium, said alloy being substantially as. permeable to X-rays as beryllium and having its malleability increased by the member of said class to a; suflicient extent to render Y the alloy hot workable.

- lium and having its malleability increased by the member of said class to a sufllcient. extent to render the alloy hot workable.

GERARD E.- CLAUSSEN.