US2167684A - Alloy - Google Patents

Description

Patented Aug. 1, 1939- UNITED STATES PATENT OFFICE Ilium Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Application February 15, 1937, V Serial No. 125,817

4 cum (oi. 15-159) The invention relates to alloys composed predominantly of copper, and has to do especially with an improved alloy containing copper, beryllium and nickel.

5 Copper-beryllium alloys are characterised by their susceptibility to Precipitation hardening eflected by suitable heat treatment, such alloys containing from about 1% to by weight of beryllium being, susceptible to such treatment.

. )0 Such alloys containing 2% and upwards of beryllium have some excellent qualities but are not sufliclently susceptible to working to make them well suited fbi' some uses. Also such copper-beryllium alloys, in theheat hardened state 15. are subject to softening when subjected in use to elevated temperatures.

I have discovered that it is possible by the addition to such copper-beryllium mixtures contalning upwards of 2% to about 6% of beryllium of suitable amounts of nickel, ranging upwards of 1% to about 8% and preferably from 1.25% to 5.0%, to produce alloys having working properties notably superior to the corresponding copper-beryllium alloys, substantially higher hard- 5 ness (Brlnell) in the heat hardened state and the ability, in the heat hardened state, to withstand elevated temperatures about nfty degrees higher than can the corresponding copper-beryllium alloys. Furthermore, the tensile strength and elongation under tensile stress of my improved alloys are at least equal to the corresponding copper-beryllilnnalloys: Nor do my new alloys show substantial impairment of electrical conductivity as compared with the copperberyllium alloys. The new alloys are also characterlsed by excellent casting properties,- castings made from them being distinguished by unusual soundness and a fine grain structure whereas'no little difficulty has heretofore been 40 had in the production of sound castings from copper-beryllium alloys; The properties of my copper-beryllium-nickel alloys naturally vary within'the composition limits of upwards of 2% to 8% beryllium and upwards of 1% to 8% nickel. 4: Alloys ranging upwards 012% to8% beryllium and 1.25% to 5% nickel have a desirable combination of properties iltting them for many different uses and, generally speaking; I consider this range 'of compositions as preferable. In the preparation of the new alloys it isco'nvenient to have on hand copper-beryllium master alloy which may range from 8% to 10% beryllium content. in copper, it is also desirable to have available 55 a copper-nickel alloy. containing from 10% to Since nickel dissolves slowly 40% of nickel. 'Pure copper is also required. The relative components are first weighed out, with an allowance of 5% to 10% for loss of beryllium by oxidation during alloying. The copper and the. copper-nickel alloy are then melted. 5 together and the copper-beryllium alloy is added last. A clay and graphite crucible may be used. The lowest pouring temperature possible should be used in order to avoid porosity in the casting.

After casting,'the alloy may be forged, or heat 10 treated directly without forging. The best ternperature for forging is about 750' 0.480 C.

The heat treatment for the production of precipitation hardening suitable for the new alloys consists of the two steps of quenching from a it suitable elevated temperature and reheating at a lower temperature, the treatment being of the same general character employed for the precipitation hardening of copper-beryllium alloys but differing somewhat as to the preferred temperaso tures employed. The first step consists in heating the alloy to a temperature high enough to bring all or most of the beryllium into solid solution, a temperature of about 830 0. being suitable. This is somewhat higher than the temas perature most suitable in the ,case of plain cop-- per-beryllium alloys. After this initial heating which may last as much as two hours at the maximum temperature, the alloy is quickly quench'ed so as to retain the various components 80 in the solid solution into which they have been more or less entirely transformed by the heating. 'Ihe'longerthe exposure to the maximum temperature, the more complete is the solution.

After quenching from the elevated temperature 86 the material is reheated to 'a temperature of 800 C.1to 850 C. to eifect the precipitation hardening. The time of exposure tothe lower or hardening temperature may be varied widely, depending upon the properties desired. the tem- 4o perature employeg, and the d ree and kind of working previously performed on the alloy. While I have mentioned the preferred range of temperature as 300 C. to 350 (3., higher and lower temperatures may be employed. The specifled range of temperature, it may be noted, is about flfty degrees higher than that most suitable forplain copper-beryllium alloys.

The presence of nickel in my alloys retards the precipitation of the hardening component so that the rate of cooling from the high temperatures, during the initial step of the hardening' treatment, does not need to be so high. This is'of advantage in hardening large cross sections for which the ratio of surface to mass is low. s

with corresponding. difiiculty in extracting the heat quickly even with water quenching. ,For thin cross sections where the ratio of surface to mass is high, it becomes increasingly possible to use air quenching, while moderate sized sections can be quenched in oil as has been found preferable in hardening steel, when minimum deformation is demanded. This feature is of especial value in the case of castings. the re-heating to eflect hardening, the presence of nickel in my alloys makes the exact time of reheating at any given temperature much less critical than for plain copper-beryllium alloys, the danger of softening the nickel alloy by too long exposure being reduced.

I have found that a more homogeneous structure is obtained after hardening, if the alloy has first been subjected to hot or cold working. With this in view, such working may advantageously be eflected between the initial quenching from high temperature and the subsequent final heat treatment to effect hardening.

As an example of the improved properties which characterize the new alloys, a copper-beryllium alloy containing 2.39% beryllium had maximum Brinell hardness, in the hardened state, of 375 while an alloy with substantially the same (2.38%) beryllium content and 1.98% nickel content had a Brinell hardness of 387. The plain beryllium-copper alloy attained its maximum hardness by re-heati g for two hours at 300 C. but when heated to lthe same temperature for twenty hours its Brin ll hardness dropped to 290 and a further heating for six hours at 330 C. caused its Brinell hardness to drop further to 269. On the other hand, the copper-beryllium-nickel alloy withstood the same entire treatment without any reduction of its hardness and the same alloy when subjected to a temperature of 330 for twenty-six hours after reaching its maximum Brinell hardness of 38'! suffered only the slight reduction in hardness to 381. The increase in Brinell hardness resulting from the addition of nickel to copper-beryllium alloys containing upwards of 2% beryllium may run as high or h gher than points.

The improved properties of my alloy are also outstanding in comparison with prior ternary alloys of copper, beryllium and nickel. An alloy of my invention composed of 2.3% beryllium, 1.1% nickel, 0.1% iron and theremainder copper, in rolled sheet'form, showed a maximum tensile strength of 211,000 pounds per square inch and 2% elongat on, in comparison with 193,000 pounds per square inch and 2% elongation for an alloy in rolled sheet form containing about 2.25% beryllium, about 0.5%' nickel, about 0.1% iron and balance copper. Also, the second of these two alloys has a proportional limit of 55,000 pounds per square inch, whereas my improved alloys have proportional limits varying from 75,000

- pounds per square inch to 100,000 pounds per square inch. My improved alloys have electrical conductivities fully as high as that of the above alloy having 0.5% nickel, when both alloys have been heat treated to give their maximum mechanical properties. The foregoing proportional limit values were determined on specimens of two inches gauge length.

The fields of use for which my improved alloys are especially adapted are more or less indicated by what has been said about the properties of the alloys and the characteristics of their hardening treatment. The soundness and fine grain structure on casting and the latitude as to rate of Furthermore, in

cooling and length of exposure to heat in the heat treating steps especially adapt the new alloys to use for the production of castings. Obviously, the marked extent to which the new alloys are susceptible of working well adapt the alloys for the production of forgings and products otherwise subjected to working in their production. The resistance of the alloys to elevated temperatures without loss of hardness makes them especially adapted for such uses as dies, molds for the casting of metals and the formation oif plastics, welding electrodes, turbine blades, electrical contacts, and springs required to operate at elevated temperatures. My alloys also are highly resistant to abrasion.

Metallographic sectionsof my improved alloys quenched from temperatures ranging upward from about 800 C. to near their melting points, show an unusual metallographic phase. This part may be quite visible after polishing and without etching, appearing as a much harder phase of the alloy. Its frequently dentritic form suggests separation at a high temperature, though it readily changes to a globular form. The usual alpha phase of copper-beryllium alloys is always present and the known beta phase of such alloys may also be present, depending upon the relative amounts of nickel and beryllium used. Since the new phase appears in greater quantities with increase in nickel and beryllium contents, quite possibly it is a combination of nickel and beryllium, with or without copper, which forms the precipitation hardening agent appearing in these alloys in the alphaand beta phases on re-heating. Whether it replaces the customary hardening phase of plain beryllium copper or appears in addition to it, is not now certain, nor is it known whether the new phase may itself decompose on re-heatlng. In any event, it appears that these new alloys show a distinctive metallographic phase.

Increase in nickel content above 1% with corresponding increase in the new metallographic phase seems to militate against the occurrence of the beta phase often found in beryllium-copper quenched from about 800 C. or above. Such beta phase in alloys of 2% to 2.5% beryllium quenched from 800' C. and above, would not be expected from the latest of the known published beryllium-copper equilibrium diagrams and where such beta phase occurred in prior investigations it was commonly believed to occur because of lack of equilibrium in the alloys. I have found, however, that at the above temperature, the beta phase is a normal equilibrium phase in binary alloys having more than about 2% beryllium. The effect of adding nickel to beryllium-copper alloys containing more than about 2% of beryllium is to cause the beta phase to disappear wholly or in part, or possibly to replace it with the new phase. This is apparent with more than 1% added nickel and quite marked with 2% added nickel. The advantages of my new alloy are believed to spring from the characteristics of the new phase as well as fromthe suppression of the beta phase. I note. especially that the new phase is dispersed within the grains in small globular particles instead of being located at the grain boundaries in relatively large angular particles as is the case with the beta phase. The globular form and dispersed distribution of the new phase are advantageous in suppressing grain growth without the attendant weakening of the whole alloy which often proceeds from the inclusion of the beta phase at the grain boundaries of the aromas alpha phase. Such weakenin: is especially marked in drawn alloys containing the hard beta phase since the drawing of such alloys may produce minute internal fractures which endurance limits. C

In my experience commercial beryllium-copper, nickel. and copper always contain some impurities such as iron, aluminum, silicon, cobalt, and zinc. While these elements ,undoubtedly have a' small eii'ect on the resulting alloy. in defining my im- A proved alloys as composed of copper. beryllium and nickel I do not mean to exclude such other elements in any amounts insuiilcient substantially to alter the characteristic properties of the alloys. Commercial heryllium copper generally contains iron in the neighborhood of 0.1% and may reach an amount as great as 0.85%: -silicon may be present from 93% to 0.1%: nickel generally contains 1% cobalt, while "high grade" copper may contain up to a total of 0.1% of several impurities lower their including zinc. Lead and antimony are deleterione even in very small amounts. Aluminum is present with beryllium in amounts ranging from r csnrmcsm Patent No. 2,167,681

0.01% to 0.2% depending on the eiiieicncy of its separation troin beryllium.

What I claim is:

l; A copper base alloy containing beryllium in an amount within the range of upwards of 2% to 6% and which would cause the presence or the known beryllium-copper beta equilibrium phase ii the binary combination is quenched irom a temperature of 800 C.; nickel in an amount within the range of upwards oi" 1% to 8% and 1( which is eil'ective substantially to suppress the said beta phase: and the remainder substantially all copper.

-2. Analloy asclalmedinclaim 1, wherein the beryliiumis upwards of 2% to 3%, and the nickel 1 content is from about 1.25% to 5%. e

8. An alloy containing from substantially 2.25% to 6% or beryllium, upwards o! 1% to 0% of nickel.. with the remainder substantially all copper.

4. An alloy containing irom substantially 2.25% g to 3% of beryllium and from 1.25% to 5% nickel, with the remainder substantially all copper.

m B. SAWYER.

or connection.

August 1, 19 9.

cHARLEs B. sauna.

It is hereby certified that error V appears in the printed specification or the above numbered patent requiring correction as follows: Page 2, secondcolmnn, line 20 for the word "part" read phase; line for "phase" read part; and that the said I-otters Patent should be read this correction therein thatthe 'same may conform to the record of the case inthe Patent Office.

Signed and sealed this 5th day of (Seal) September, A. n. 1959.

Henry Van Arsdale, Acting Commissioner of Patents.

aromas alpha phase. Such weakenin: is especially marked in drawn alloys containing the hard beta phase since the drawing of such alloys may produce minute internal fractures which endurance limits. C

In my experience commercial beryllium-copper, nickel. and copper always contain some impurities such as iron, aluminum, silicon, cobalt, and zinc. While these elements ,undoubtedly have a' small eii'ect on the resulting alloy. in defining my im- A proved alloys as composed of copper. beryllium and nickel I do not mean to exclude such other elements in any amounts insuiilcient substantially to alter the characteristic properties of the alloys. Commercial heryllium copper generally contains iron in the neighborhood of 0.1% and may reach an amount as great as 0.85%: -silicon may be present from 93% to 0.1%: nickel generally contains 1% cobalt, while "high grade" copper may contain up to a total of 0.1% of several impurities lower their including zinc. Lead and antimony are deleterione even in very small amounts. Aluminum is present with beryllium in amounts ranging from r csnrmcsm Patent No. 2,167,681

0.01% to 0.2% depending on the eiiieicncy of its separation troin beryllium.

What I claim is:

l; A copper base alloy containing beryllium in an amount within the range of upwards of 2% to 6% and which would cause the presence or the known beryllium-copper beta equilibrium phase ii the binary combination is quenched irom a temperature of 800 C.; nickel in an amount within the range of upwards oi" 1% to 8% and 1( which is eil'ective substantially to suppress the said beta phase: and the remainder substantially all copper.

-2. Analloy asclalmedinclaim 1, wherein the beryliiumis upwards of 2% to 3%, and the nickel 1 content is from about 1.25% to 5%. e

8. An alloy containing from substantially 2.25% to 6% or beryllium, upwards o! 1% to 0% of nickel.. with the remainder substantially all copper.

4. An alloy containing irom substantially 2.25% g to 3% of beryllium and from 1.25% to 5% nickel, with the remainder substantially all copper.

m B. SAWYER.

or connection.

August 1, 19 9.

cHARLEs B. sauna.

It is hereby certified that error V appears in the printed specification or the above numbered patent requiring correction as follows: Page 2, secondcolmnn, line 20 for the word "part" read phase; line for "phase" read part; and that the said I-otters Patent should be read this correction therein thatthe 'same may conform to the record of the case inthe Patent Office.

Signed and sealed this 5th day of (Seal) September, A. n. 1959.

Henry Van Arsdale, Acting Commissioner of Patents.