News of Science and Technology

ALLOYS OF URANIUM WITH PLATINUM SERIES METALS

Data reported in the literature [1,2] on alloys of uran- Ium with metals of the platinum series are of practical in- terest, since "flssium', i.e., the residue left over from the fission-product elements following pyrometallur.gical pro- eessing of the irradiated uranium, consists mainly of ruthen- ium (83%), rhodium and palladium (10%), and molybdenum

,(42%) [3]. These data are also important in the study of the behavior of modifications of uranium when fused with other elements.

The Uranium-Ruthenium System. An incomplete phase diagram of this system (see Fig. 1) is based on micro- scopic and thermographic researches. Transformations in the solid state proceed very slowly. The solubility of ruthen- ium in c~ uranium at 638"C comes to 0.1 wt. %, whereas the solubility of uranium in ruthenium at 1500~ Is about 0.9 wt. qo. Compounds assigned the tentative composition UsRu4, U~Ru~ and UsRu s are probably formed in peritectie fashion, since the liquidus rises without open maxima right up to the melting point of ruthenium (2500"C). The com- pound URu s is formed from a periteetic reaction and has a cubic structure of the CusAu type, with a = 3.988 + 0.002 A [4].

0 S ~200

I

\

~oo \ \

1000

u

900

t.-, 800

700

605

~0 r 20

The Uranium-Rhodium SystemJ The uranium corner of this system is shown in Fig. 2, based on dat a reported in

[1,2]. Up to the compound URh, the diagram is reminiscent

of the diagram for ruthenium, except that U2Rh is formed

from a peritectoid rather than a peritectic reaction. The

liquidus rises to a peak at 2160~ at 63 wt.g~ thodium and

then falls to 1500~ at 78 wt. ~ rhodium. The compound

UP, h s has a cubic structure of the CusAu type, with a = 3.991

A [4]. The Uranium-Palladium System (FigL 8) [5.]. The

solubility of palladium in a and B uranium is less than 0.8 at. %. The peritectold temperature at which the solid solution of uranium in palladium forms is assigned arbi- trarily (it is higher than 1425"C). The solubility of uran- ium in palladium is great and fluctuates from 22.2 at. % at 700-900"C to 21.8 at.~]o at 1400"C. The compound UPd s features a hexagonal lattice, varying from a = 5.769 A and c = 9.641 A on the part of uranium~to a = 5.768 A and c = 9.526 A on the part of palladium.

The Uranium-Osmium and Uranium-Iridium Systems [1.~]: Scanty data have been published about these systems.

Ruthenium, wt. ~ 25 30. 35

i / , f /__ !~ ~o

/ H

d + URu

947"*2 L

u 2 eu. u~u

-U2Ru

i I i

12 uRa + u 3 Ru~

i I r

-uRu I J.

5O

/ /

/ /

/ \ \ , d / \ \ /

-\ \ I \\ dv \\ /

~*u~Ru

6 3 3 2 5 ,

r" ~ X l e(~ U 2 ~ u R

t0 20 30 ~0 Ruthenium, at. %

~0 ~5 EO $5 60 i i i I

t

870~-t0

U 2 Ru a �9 VRu a

60 70

Fig, 1. Phase diagram of urarfium-ruthenium system.

443

Rhodium, wt. % 5 t0 20 30 z,O 60

......... I I , i il 1

1200 ~ d ~ " - - I

d4 ~lRh

800 . c~ / 755 ~ 5 r ,8 . .~

6OO U z eh*g,r

~oo '~+UzRh U2~h" [ 0 ZO 40 60 80

R h o d i u M , a t . ~/~

Pig. 2. A part of the uraNium-rh0dium phase diagram.

1800

Palladium, wt.q~ 5 10 '20 30 ~0 60 80 ! I I I

~ t 4

1700

u ~f300 ....... =,_, ~1200

~' nO0

fO00

900!

d

Z§

1640

/1"o,

. -[ d

i :=

i / L / d.~ F , L t .

r

nfo t; , r

971 ~ , r%, suO : ' , �9 / { I I

J

/

8 0 ~ ... . . - i

756

70o "~ ~'~ L, L= ~,r 66s,,, I ' 600

0 10 ZO 30 ~0 50 60 70 80 Palladium, at. ~

90 fO0

Fig. 8. Phase diagram of the uranium-palladium system.

2000

1800

t500

L) o

~ 1200

I D

~000

8OO

600

400 L'

Fig. 4. system.

[ /

/ / '

/ , I I 17~

589 - -

v~-' $

Platinum, wt. % E fO ZO 30 40 50 60 70 80 90 i i i , i ~ [ i i l

d

i / i4

, / d,

r I

E

foo

�9 I

20 40 60 80 10o Platinum, at. %

Tentat ive phase diagram of uranium-platinum

Osmium stabilizes the B and y phases. The solubility of iridium in uranium at 890*C is of the order of 3 at. %. Compounds UO~ and UIr z of the MgCu 2 type, with face- centered lattices having a = 7.5125 ~ 0.0005 A and a --- = 7.509A, respectively, have been identified.

The Uranium-Platinum System [1]. A tentative dia- gram of this system is seen in Fig. 4. The maximum solubility of platinum in 7 uranium at the eutectic point is 6.5 at. %~and in B and a uraniumj3.0 at. % .and 0.3 at. %. The solubility of uranium in platinum is about 5 at. %. The structures of the compounds UPt~, having a rhombic lattice with a = 4.12 A, b = 9.69 A,and c = 5.64 A0 and UPts, having a hexagonal latt ice with a = 5.764 A and c = 4.898 A, have been identified.

G . Z .

L I T E R A T U R E C I T E D

1. V. Rough and A. Bauer," Constitution of uranium and thorium alloys," BMI-1300, Iune 2, 1958.

2. H. Chiswik et al., "Advances in the physical metallurgy of uranium and its alloys," Paper No. 713 (USA) pre- sented at the Second International Conference on the Peaceful Uses of Atomic Energy (Geneva, 1958).

3. L. Koch, Nucleonics 16__, 68 (1958). 4. T. Heal and G. Williams, Acta Cryst. 8, 494 (1955). 5. J. Catteral et aL, J. Inst. Metals 8__55, 63 (1956-195'/).

BRIE F COMMUNICATIONS

USSR . A new cycl ic ion accelerator incorporat- ing a new design, and constituting a further development of the cyclotron, has been put into operation in the Nuclear Problems Laboratory of the Iofnt Institute for Nuclear Studies at Dubna. As distinct from the con- ventional cyclotron and synchrocyclotron, the azimuthal magnetic-field strength does not remain constant in this accelerator, but varies with a certain periodicity. The lines of maximum magnetic field strength (the "humps ' ) take the form of Archimedes spirals evolving from the center of the magnet. However, the mean magnetic field (during one period of revolution of an ion) does not fall off radially as in the cyclotron and synchrocyclotron, but increases continuously in order to offset the relativistic mass increase of the ions with tnerease in energy. Beam defocuslng along the vertical and degradation of beam strength, usually due to increase in the mean magnetic field, are el iminated in accelera-

tors of the new type by the focusing action provided by azimuthal variation of the magnetic field.

Proton energies in the new type cyclotrom may be brought up to the same level as in synchrocyclotrons (to 1 Bey), and currents are hundreds of times higher.

A detailed description of the accelerator put into service at Dubna will be published tn the next issue of IAE.

USSR . The Ninth Annual Conference on Nuclear Spectroscopy was convened in Kharkov, January 26 to February 2, 1959, and was attended by over 350 scientific workers in research institutes and advanced educational institutions. Over a hundred reports were heard at the Conference, dealing with the results of theoretlcal and experimental research into the structure of nuclei , co and B decay. A more complete report on

445

the Conference wlll appear in the July issue of IAE, and the proceedings of the Conference will be made available in the Bulletin of the Academy of Sciences of the USSR, physical series.

.U.SSR . A simple coincidence circuit with a resolving time of less than 10 -9 see has been developed at the Institute of Physics of the Academy of Sciences USSR. Germanium diodes, such as the DG-Ts8, D~V, or D2A , which have a low forward resistance, can be used in the circuit. The small resolution time and high efficiency are achieved by virtue of the fact that the diodes are not loaded by a d c bias current. The scheme is based on the differentiation of single isolated pulses when there is no signal present in the second input circuit. Pulses applied to.the input of the ~rstem simultaneously (within the limits of the resolution time) are not differentiated. The circuit has been used in work on investigations of photo- production of lr ~ mesons in complex nuclei, where a resolution time of I . 10 "~ see is needed , and in investiga- tions of the time characteristics of the FEU-33 photo- multiplier (which requires a resolution time of ~10 -9 see).

US SR . A simple pulse-amplitude integrator has been developed at the Nuclear Physics Scientific Research Institute of Moscow State University; with this instrument it is possible to total the amplitudes of successively applied pulses and to determine the mean amplitude (for small loading of the detection channel). The device is based on the transformation of the signal into a train of pulses in such a way that the number of pulses in the train N is determined uniquely by the amplitude of the input signal V a. The totaling of the number of pulses in the trains of the output of the amplitude converter is carried out by a counting device with a capacity of 10 s and a resolution time of 5 �9 ]0 -~ see. Used in conjunction with a large 10-channel time analyzer which analyzes the trains by length (by means of a delay circuit in the form of ten successively triggered univibrators) and parallel registra- tion by neon lamps, the system makes it possible to obtain the pulse amplitude distribution in a form convenient for analysis and to determine the mean amplitude of the pulses at the same time. The instru- ment has been used for recording the mean amplitude of signals characterized by low counting rates (.-' i0 min" 1) obtained from an ionization chamber used to measure the ionization properties of cosmic radiation.

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