US1975112A - Beryllium alloy - Google Patents

Description

Patented Get. 2, 1934 I 1,975,112

I "UNITED STATES PATENT OFFlCE BERYLLIUM ALLOY Georg Masing, Berlin, and ()tto Dahl, Berlin- Charlottenburg, Germany, assignors, by mesne assignments, to Metal & Thermit Corporation, New York, N. Y., a corporation of New Jersey No Drawing. Application May 13, 1927, Serial No. 191,263. In Germany May 21, 1926 8 Claims. (Cl. 75-1) The invention relates to alloys of beryllium with high temperatures, preferably above 600 C. and copper and phosphorus. The copper content after sufiiciently rapid cooling, by chilling in the of the new alloys preponderates over theberylcase of large pieces and by cooling in the air in lium content which preferably should be less than the case of small pieces, they are subjected to .5 per cent and at most amount to about 12 per a second thermic treatment at lower temperacent, while the phosphorous content varies from tures, preferably between 150500 C. The duraa trace to about ,1 per cent. In addition, other tion of the last mentioned thermic treatment elements-for example tin, zinc and aluminiumdepends primarily on the temperature; whereas may be present. By the presence of a little in the neighbourhood of the lower temperature it) beryllium, copper is given new and valuable proplimit it may amount to several days, only two Q35 erties, including the possibility of being hardened hours will sufiice at 300 C. and the time reto steel-like hardness. By the use of the stated quired becomes progressively shorter at higher other elements as auxiliaries, the new results may temperatures. By means of this double heat be obtained with a less proportion of beryllium. treatment it s possible, for example, to raise the lit Copper-beryllium alloys are of a yellowish, hardness of an alloy consisting of 97 per cent to somewhat bronze like color or are somewhat paler of copper and 3 per cent of beryllium from about and are characterized by great hardness, 125 to 360 Brinell. units. The tempering eilect strength, and resistance to corrosion. They thus of this heat treatment is also obtained in the case possess qualities that certain circumstances of a beryllium content above the aforesaid limit considerably surpass those of the best bronz'es of 5 per cent but in the case of such higher pertit; and are somewhat similar to the properties of centages the tempering effect is so greatly overhardened steel. The alloys may be prepared, for rshariowed by other changes in the alloy as not example, by fusing together copper and beryllium, ,tobe directly appreciable; nevertheless, this heat referably after first alloying the beryllium with treatment may be advantageous even in the case another metal, with, if required, the addition oi of these alloys for certain purposes which demand an other elements such as tin. zinc, and aluminium. the combination of a certain hardness and According to the invention an alloy of the aforetenacity. said type is subjected in the solid state to a refin- While the tempering process hereinbefore deing heat treatment. scribed is applicable to all copper alloys con- As exhaustive experiments have shown, beryltaining up to about 10 per cent of beryllium, the 95 liurn alone or in the presence of other metals is two processes now to be described are intended an excellent hardening agent for copper. In parfor use only with beryllium alloys of that type in ticular, it enables the properties of the prepared which on solidification of the melt there first alloys of the above mentioned range of berylseparates out a very hard ,B-crystal form which lium mntent to be improved by suitable thermic breaks down at a temperature below about 580 treatment, so that on the one hand the alloys can C. Such are the alloys containing from 3-12 per be put into a condition of sufiicient softness and cent of beryllium. By the addition of other eleductility for rendering them suitable for working ments, such as tin, zinc and aluminium, the conby kneading and by cutting tools and, on the centration and temperature limits of the e-form an other hand, by means of another therrnlc treatare in their entirety shifted preponderatingly toas meat, some of these alloys can be given degrees ward the side of the low beryllium content. In of hardness surpassing that of hardened steel. other words, the presence of the other elements By properly gauging the thermic treatment any permits the use of smaller amounts of beryllium required intermediate degree of hardness, in attaining the same results; they have an auxil- 5 strength and toughness can be imparted. The iary action. It is evident that the range of aptoo alloys exhibit, in addition to good technological plic'ability of the processes to be described extends propertie a variability by therrnic treatment to in each of these cases over the range of existence an extent hitherto unknown in other copper of the fi-crystals with reference to the changed alloys. temperature relationships.

50 The character of the thermic treatment de- The object of the first of the two processes now pends upon the composition of the alloy and the to be described is to imparta high degree of purpose in View and will now be described. in hardness to the alloy. For this purpose, the alloy the case of alloys. containing up to about 5 per is quenched from a temperature above the breakcent of beryllium the following thermic treatment ing down temperature of the p-crystals,this in 5 is very advantageousr-the alloys are heated at the case of the pure copper-beryllium alloys is ins and thus acquires a notched bar test toughness always above about 580 C. In this manner it is possible to impart, for example, a hardness of 730 to a copper-beryllium alloy with 6.7 per cent of beryllium which alloy originally has a hardness of 490 in the chilled casting.

It on the other hand it is required to obtain an alloy of this group in a workable condition, this is done by annealing 'at atemperature below that of the breaking down of the p-crystalsthus, in the case of the pure copper-beryllium alloy, below 580 C.and so completely breaking down the fi-crystals and obtaining the alloy in a comparatively soft condition; its hardness in the case of a 6.7 per cent beryllium content will thus be brought to about 2&0.

As already stated, the last mentioned process may be combined with the first mentioned thermic treatment.

The various thermic treatments described may be applied to cast as well as to worked alloys.

If it be desired to obtain copper-beryllium alloys having a high ductility and toughness in addition to considerable strength we may proceed as follows:-

The alloy is, after a preliminary mechanical treatment (working, as by hammering, rolling, etc.) or chemical treatment, if such preliminary treatment be required, heated to temperatures below those given for the first heating-for example, below 600 C.--but above the temperatures of the second heating-for example, above 450 C. The alloys can also be heated for a rather long time at somewhat lower temperatures at which practically only a hardening effect is produced which, however, on longer heating is replaced by .a high ductility and toughness in addition to considerable strength. As the heating can be interrupted at any suitable moment it is possible in this way to produce, as desired, alloys having within wide limits definite values for hardness, ductility, toughness and strength.

Practically identical with the heat treatment described is one in which the alloy is heated at a temperature higher than 600 C. and then slowly cooled.

For example, a copper-beryllium alloy contain- 2.5 per cent of beryllium is heated at 500 C.

of about 15 meter kilograms per square centimeter with a strength of over '75 kilograms per square millimeter, while the same alloy after being thermally treated as above described by being heated twice at different temperatures-for example, above 600' C. and up to about 450 C.- exhibited a notched bar test toughness of only 1 meter kilogram per square centimeter with a strength of 140 kilograms per square millimeter. It has been discovered in this connection that substantial results are obtained with the single heating process only when the beryllium content of the alloy amounts to at least 1 per cent.

It has further been discovered that very valuable properties can be imparted to a copperberylliumalloy with a low beryllium content by the addition of up to 1 per cent of phosphorus. The thermic tempering process of the copperberyllium alloy is accelerated by the phosphorus content and, moreover, a considerable improvement of the properties is effected by this thermic treatment even in the case of a low beryllium content, so that the addition of phosphorus at the same time renders possible a saving in costly metallic beryllium; in this case one or more otherelements-for example, zinc, tin, aluminium, and magnesium-may also be present in the alloy.

The thermic treatment of a copper-beryllium alloy containing phosphorus is carried out, for

example, as follows:

An alloy containing about 0.25 per cent of phosphorus and about 1.50 per cent of beryllium was heated at about 800 C. and then quickly cooled. After cooling, its hardness amounted to about units. By then heating the alloy for an hour at 350 C. the hardness was increased to 210 units. When, on the other hand, a copperberyllium alloy with the same beryllium content but free from phosphorus was subjected to a corresponding thermic treatment, the hardness, after rapidly cooling the alloy from 800 C., amounted to '74 units and even on heating the alloy for seven hours in this case the hardness rose only by about 20 units. From this example the considerable improvement of the alloy by the addition of phosphorus is clearly evident.

After the above described copper-berylliumphosphorus alloys have been subjected to one or more of the above mentioned tempering heat treatments, they are very suitable for use as material for metallic springs, for example as leaf, helical, or spiral springs as well as for parts of machinery or apparatus that are subjected to friction, especially axle bearings, commutators, sliding contacts, or other electric current conducting members.

By the expression balance substantially copper found in the accompanying claims we mean that the alloys called for may contain small quantities of addition metals, such as aluminum, tin, silver, magnesium and zinc in proportions insufiicient to substantially change the characteristics of the said alloys.

What we claim as our invention and desire to secure by Letters Patent is:

1. An alloy characterized by hardness, strength and resistance to corrosion, containing from about 0.3 to 12 per cent of beryllium and from about 0.1 to 1 per cent of phosphorus, with a remainder substantially copper.

2. An alloy characterized by hardness, strength and resistance to corrosion, containing from about 3 to 12 per cent of beryllium and from a trace to about 1 per cent of phosphorus with a remainder substantially copper.

3. An alloy characterized by hardness, strength and resistance to corrosion, containing from about 0.3 to 12 per cent of beryllium, a phosphorus content of from about 0.1 to 1 per cent and also containing from about 0.1 to 8 per cent of aluminum, with a remainder substantially copper.

4. An alloy characterized by hardness, strength and resistance to corrosion, containing from about 3 to 12 per cent of beryllium, a phosphorus content.varying from a trace to about 1 per cent and also containing from about 0.1 to 8 per cent of aluminum, with a remainder substantially and also containing from about 0.1 to 8 per cent of tin, with a remainder substantially copper.

'7. An alloy characterized by hardness, strength and resistance to corrosion. containing from about 0.3 to 12 per cent of beryllium, a phosphorus content of from about 0.1 to 1 percent and also containing from about 0.1 to 8 per cent of zinc, with a remainder substantially copper.

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