DE1950973B2 - BERIYLLIUM ALLOY - Google Patents

Description

1 2

The invention relates to a beryllium alloy, named type both in common and in

which contains 0.05 to 3% calcium. increased temperature by adding a certain

Beryllium alloys are used for various purposes, including iron, palladium, gold, platinum, or iridium

genes that can be improved considerably at high temperature in an oxy-rhodium. in the atmosphere and especially in the hot 5 contrast to the previously known beryllium alloys

Zones of nuclear reactors in which the heat dissipation becomes the corrosion resistance of this new

guidance takes place through a carbon dioxide gas cycle, alloys against carbon dioxide gas through the

are stable and usable. The components of a presence of the additional element favorably influenced,

such nuclear reactor are at the same time the effects. A micrograph of such a new beryllium from Heat, mechanical stresses, corrosion io alloy, which one or more of the above

contains additional elements given by the carbon dioxide gas and neutron irradiation shows numerous

exposed. intermetallic precipitates, the presence of which in the

The known beryllium alloys provide the hardening obtained in the area of the matrix, but such uses are not entirely satisfactory. Furthermore, as results are found, these precipitates. For example, the German version 15 shows the movement of the gas bubbles in the irradiated Auslegeschrift 1181 923 known binary beryllium beryllium obstructed, and more effectively, depending on the alloy with 0.05 to 3% calcium content up to 700 ⁰ C finer, more numerous and more uniform distributed the Ausein satisfactory behavior in carbon dioxide gas that are precipitates.

however, better mechanical properties are and it has also been found that higher heat creep resistance is desirable. Under 20 treat the structure of the new beryllium alloy Neutron irradiation shows this alloy can be improved rapidly and then relatively cracks. The same applies to those from the German moderately fine grain possesses and the distribution of the inter-Auslegeschrift 1179 719 known ternary beryllium metallic precipitates remarkably fine and alloys, which is 0.1 to 3% calcium and 0.1 to 2% moderate.

Contains zirconium, niobium, vanadium or tantalum and 25.

Incidentally, although better mechanical properties, proposed according to the invention a beryllium alloy,

However, a lower corrosion resistance than that in percent by weight consists of 0.05 to 3%,

having the former alloy. preferably 0.3 to 0.8%> calcium, 0.15 to 3 ⁰ I ₀ ,

The cracking of beryllium and its alloys - preferably 0.15 to 1%, iron, palladium, gold, gene under neutron radiation is caused by gases, before 30 platinum, iridium and / or rhodium and the remainder beryllium, all helium, which develops under the A preferred alloy according to the invention the neutrons in the metal due to the following holds 0.15-0.5% iron; another preferred erreactions form: the alloy according to the invention contains 0.2 to 1% palladium

«So medium.

Be + η - * ■ Be + 2n ₃₅ £> _{as a} method according to the invention for heat

B _e 8 _ _> ^{2He 4} treatment of a beryllium alloy according to the invention

B »4- H ^e 4-H ^{4 run} * = ^ ^er ° k ^en g ^e g ^e ^ ^ene composition

Be · + - η - »■ tie - + - e characterized in that the alloy 1 to

He ⁶ - * Li ^e heat-treated for 10 hours at 750 to 950 ^{0 C,}

Li ^e + η -> He ⁴ + H ³ 4 ° ^{cools and renews 10} . ^{to 20} ° hours at 500 to 700 ⁰ C.

is heat treated.

The gas atoms which originally had places in the beryllium alloys according to the invention can

Occupy the proximity of the places of the beryllium atoms, from nen by known powder metallurgical processes

where they are created, migrate and unite, the powder being produced by grinding

finally to gas bubbles at the grain boundaries and 45 chips obtained from cast ingots

also in the matrix. Is held under the action of mecha-. The bars can be made from an electrolytic

niches or thermal stresses that the workbench or other metal produced

can be stored in operation and at elevated temperatures. The metal is preferably

is thrown, the gas bubbles grow at the grain boundaries and then the resulting

through existing or developing gaps and 50 bars directly through extrusion, forging

lead to the complete detachment of the grains from or processed rollers,

each other. The following tables give the

While it is impossible to determine the formation of these gases Properties of beryllium metals according to the invention

To prevent it, you can reduce the speed in comparison with beryllium and known ones

flow with which the gases migrate, and the point in time 55 beryllium alloys. Served as the starting material

delay where the beryllium accumulated at the grain boundaries - in all cases electrolytically obtained.

Melt amount of gas becomes dangerous and cracking The beryllium metal A was made by powder metallurgy

brings about. received and is a sintered beryllium. B is a

The invention is therefore based on the object of producing an alloy with 0.4% Ca, remainder beryllium

To create beryllium alloys, the mechanical 60 of the German Auslegeschrift 1181 923; C is a

Properties and creep behavior of a common alloy with 0.4% Ca and 0.2% Zr, remainder beryllium,

and increased temperature, their corrosion resistance - in accordance with the German Auslegeschrift 1179 719.

Improved resistance to oxidation and carbon dioxide gas From alloys D and E according to the invention

and their susceptibility to cracking below D contains 0.4% Ca and 0.5% Pd; E 0.4% Ca and

Neutron exposure is decreased. With less than 65 0.2% Fe, the remainder in each case beryllium,

Applicants' investigations found that all of these alloys, except A, were made by

mechanical properties as well as creep behavior vacuum melting a mixture of flakes of

a beryllium-calcium alloy of the electrolyte beryllium and previously produced mother-

Alloy part Be-Ga, Be-Fe, Be-Pd in an induction furnace manufactured. The cast billets thus obtained were then extruded into the mold brought by round bars.

Iron is an inevitable impurity in beryllium and especially in sintered products, because the mills are mostly made of steel. However, the iron content generally does not exceed 300 ppm (0.03%) for electrolyte dandruff, 800 ppm (0.08%) for the powder obtained from these flakes and 1500ppm (0.15%) for that obtained from a magnesothermically Metal obtained powder.

The iron content of alloy E is well above these values; it is an intentional one Additive.

Table I indicates the tensile strength and elongation of the alloys D and E in the drawn (extruded) state and after heating to 800 ⁰ G lstündigem for different temperatures. Have very close values of the molded product, the 500 hours at 557 ⁰ C stabilized state and the indicated annealed condition were obtained for the raw state. Increase the additions of Pd and Fe, the tensile strength of 0.4 ° / ₀ Ca alloy containing more than the addition of Zr. The same applies to the addition of Au, Pt, Ir, Rh. You can increase the amount of

ίο Fe, Pd etc. the tensile strength properties even further improve, but above a total content of 3% of these elements, the heat processing is the Alloy very difficult.

Table II shows the superiority of the invention Alloys versus an unalloyed sintered beryllium and a binary alloy of beryllium and calcium in terms of creep behavior.

Composition of the samples (extruded and tempered):

A: beryllium]

B: 0.4% Ca, remainder beryllium [comparison

C: 0.4% Ca, 0.2% Zr, remainder beryllium J

D: 0.4% Ca, 0.5% Pd, remainder beryllium 1 _{Frfini1lI__}

E: 0.4% Ca, 0.2% Fe, remainder beryllium J ^t - ^innaun S.

Table I. 300 ⁰ C 400 ⁰ C temperature
500 ⁰ C 600 ⁰ C 700 ⁰ C 24
27
30th
28.5
40
27
10.5
21 18th
21
27
25th
65.5
58
15.5
32 12.5
15.5
24
21
55
48
28
20th 9
11.5
17.5
19th
100
46.5
40
26.5 5
6.5
9.5
9.6
130
12.5
45.5
34 Tensile strength (kp / mm ² )
B. C. D. E. Elongation at break (% on 20 mm)
B. C. D. E.

Table II

Temperature 400 ⁰ CI 400 ° CI 400 ⁰ C | 500 ⁰ C

Test load (kp / mm) 15 12 I 10 I.

500 ⁰ CI 600 ⁰ CI 600 ⁰ C 2.5 2 I 1.5

Stationary crawling speed in 10% / h

A.

B.

D.

E.

Total elongation after
100 hours

A.

B.

D.

E.

26 30 19.5 14.3

20th

22 6.5 3.9

0.26 0.16

0.07 0.05

6.3 8

3.2 1.9

0.03 0.02 12.5
50
78
9.4

0.8
0.13

6.5

3.9.

2.6

17.2 very accelerated

45 3.9

39 1.0

0.03
0.02

very accelerated

0.7 0.09

Table III gives some of the values obtained for the grain size, the size of the precipitates and the number of precipitations per unit volume, in comparison with the best values obtained for the binary alloy Be-Ca under otherwise identical extrusion conditions.

Further tests have shown that this heat treatment neither the mechanical Properties still affect the behavior of the alloy according to the invention in carbon dioxide gas.

Table III

beryllium
alloys Heat treatment Grain size in μm 90 Fallu
Number / mm ³ nong
Dimensions
(μηι) B. 1 hour 950 ⁰ C 120 small amount 10 to 30 B. 1 hour 800 ⁰ C 70 to 80 small amount 10 to 30 E. Ölgetempert 1 hour 800 ⁰ C. 90 (numerous sub _1O ok 0.1 to 0.2 and 24 hours at 600 ^° C grains) E. Oil tempered at 800 ° C for 1 hour 90 (numerous sub 10 ¹⁰ 0.1 to 0.2 200 hours 600 ° C grains) E. \ Hour 800 ⁰ C + 10 ⁵ 0.5 5 hours 700 ° C

Treatments lasting several thousand hours at 550 to 650 ^° C., the operating temperatures of heavy water gas nuclear reactors, did not significantly change the density and the dimensions of these intermetallic precipitates.

The behavior of the inventive as Alloys examined under irradiation.

The cracking of the irradiated beryllium at high temperature was mainly evident when a voltage was applied, which resulted in the growth of the helium bubbles at the grain boundaries. The mechanical testing to study these cracking caused by neutron irradiation was performed as follows: The metal was nv at 650 ⁰ C at a dose of 5 x 1O ^-20 nvt (Gesamtneutronenfluß, namely the product of the number of neutrons per unit volume and the mean velocity, integrated over time) irradiated. An imposed deformation was maintained at a temperature above COO ⁰ C, which initially produced a stress equal to the elastic limit of the metal; after the tensile stress was released, a new deformation was caused in order to reach the elastic limit again; these load cycles were continued until the specimen broke. The number of cycles before breakage indicates the degree of cracking of the irradiated metal.

A beryllium alloy with 0.4 ° / ₀ Ca with a low content of other elements from only holds one cycle; a beryllium alloy with 0.4% Ca and 1600 ppm iron can withstand five cycles before breaking.

This experiment shows the considerable advantages of the alloy according to the invention, which as a result of the The addition of certain elements has fine-grained intermetallic precipitates that combine of the helium to gas bubbles, which can lead to cracking and breakage.

Claims (7)

Patent claims: 1. beryllium alloy consisting of, in weight percent, 0.05 to 3 ° / ₀ calcium, 0.15 to 3 ° / ₀ iron, palladium, gold, platinum, iridium and / or rhodium, balance beryllium. 2. Alloy according to claim 1, characterized in that the calcium content is between 0.3 and 0.8 ° / ₀ . 3. Alloy according to claim 1 or 2, characterized in that the content of iron, palladium, Gold, platinum, iridium and / or rhodium is between 0.15 and 1%. 4. Alloy according to claim 1 or 2, characterized in that the iron content is 0.15 to 0.5% amounts to. 5. Alloy according to claim 1 or 2, characterized in that the palladium content is 0.2 to 1%. 6. A method for heat treatment of a beryllium alloy of the composition according to any one of claims 1 to 5, characterized in that the alloy is ^{heat-treated for 1 to 10 hours at 750 to 95O 0} C, cooled and heat-treated again for 10 to 200 hours at 500 to 700 ° C . 7. Use of a beryllium alloy of the composition according to any one of claims 1 to 5 or the heat treatment according to claim 6, for the production of components of nuclear reactors, in particular shells of nuclear fuel elements.