Previous publications in English | Institute of Superconductivity

Dr. Alex Friedman - publications 1969-1983

Increase in the modulation period in Ticonal
Granovskii E.B.; Fridman A.A.; Al'tman V.A.; et al.
Fizika Metallov i Metallovedenie Volume: 28 Issue: 6 Pages: 1096-8 Dec. 1969

Using X-ray diffraction measurements, the authors studied the effect of the annealing time t and temperature T on the period L of the modulated structure of an Fe-35% Co-15% Ni-7% Al-4% Cu-5% Ti alloy. It was shown that regardless of the annealing temperature, the variation in L is described by L=kt 0.21. The activation energy for the increase in L was determined at 76plusmn15 kcal/mole

Composition of phases present in ticonal (an alloy YuNDK35T5)
Zel'tser E.Ya.; Kucherova N.V.; Fridman A.A.; et al.
Fizika Metallov i Metallovedenie Volume: 28 Issue: 3 Pages: 568-9 Published: Sept. 1969

Two phases present in annealed (200 hrs at 800degC) specimens of a permanent magnet alloy 35Co-15Ni-7Al-4Cu-5Ti-Fe were separated by anodic dissolution. Chemical analysis showed that the alpha-phase is enriched by nonmagnetic metal atoms (Al, Ti and Ni) while the second phase (alpha') is iron-rich

Decomposition of the solid solution in an alloy alnico (YuNDK24)
Pashkov P.P.; Fridman A.A.; Granovskii E.B.
Fizika Metallov i Metallovedenie Volume: 27 Issue: 1 Pages: 121-6 Published: 01 1969

X-ray diffraction analysis was used to study the early stages of decomposition of the solid solution in single crystal specimens of a 14% Ni- 8% Al- 24% Co- 3% Cu- Fe alloy. Low-angle diffraction data were obtained, and the superstructural and structural reflections were studied by the Laue and rotating crystal methods

Structural changes in Alnico
Fridman A.; Pashkov P.: 2nd European conference on hard magnetic materials (abstracts) Location: Milan, Italy Date: 23-25 Sept. 1969 Pages: 47 Published: 01 1969

The solid solution decomposition of Alnico 5 and Alnico 8 is studied by means of electron microscopy and X-rays. The following sequence of the decomposition process was obtained, Alnic 5: spherical zones; periodic modulated structure; rod; shaped particles of metastable tetragonal phases; final cubic phases. Alnico 8: the sequence is the same but owing to great importance of elastic energy at the decomposition the three-dimensional modulated structure forms even during sharp quenching. The modulation wavelength increases according to a (time) n law. The activation energies of the decomposition process are determined. The spinodal mechanism of decomposition of the alloys is discussed

X-ray and Mössbauer study of alnico 8

Povitsky, V. ; Granovsky, E. ; Fridman, A. ; Makarov, E. ; Pashkov, P. ;
IEEE Transactions on Magnetics, Jun 1970 Volume : 6 , Issue:2 page(s): 215 - 217
Date of Current Version : 06 January 2003 Sponsored by : IEEE Magnetics Society

Mössbauer spectroscopy and X-ray studies have been used to investigate two Alnico 8 alloys in different stages of a thermomagnetic treatment cycle. It is revealed that the first low-temperature aging subsequent to magnetic field hardening results in redistribution of components among the alloy phases, while the second low-temperature aging causes the variation in the degree of weak magnetic phase order. The temperature range of developing effective magnetic fields on iron nuclei in the α phase is shown to lower with an increase in the degree of Fe3Al-type order.

Structural changes in alnico alloys

Pashkov, P.; Fridman, A.; Granovsky, E.;

IEEE Transactions on Magnetics, Volume: 6 , Issue: 2 1970 , Page(s): 211 - 214

The solid solution decomposition of Alnico 5 and Alnico 8 is studied by means of electron microscopy and X-rays. The following sequence of the decomposition process is found: Alnico 5: spherical zones-periodic modulated structure-rod-shaped particles of metastable tetragonal phases-final cubic phases; Alnico 8: the same sequence, but due to great importance of elastic energy at the decomposition, the three-dimensional modulated structure forms even during sharp quenching. The kinetics of modulated structure formation is studied. It is shown that the modulation wavelength increases according to a (time)ⁿ law. The activation energies of the decomposition process are determined. The spinodal mechanism of decomposition of the alloys in question is discussed.

Investigation of thermomagnetic treatment of Ticonal alloys by the Mossbauer method
Povitskii V.A.; Granovskii E.B.; Fridman A.A.; et al.
Fizika Metallov i Metallovedenie Volume: 29 Issue: 2 Pages: 247-51 Published: Feb. 1970

Using Mossbauer spectroscopy and X-ray diffraction, the authors studied two Ticonal alloys (35Fe-35Co-14Ni-7Al-4Cu-5Ti and 27.5Fe-40Co-14Ni-7Al-4Cu-7.5Ti) at various stages of thermomagnetic treatment. It was established that the first low-temperature treatment after quenching in a magnetic field leads to a redistribution of components between alloy constituents, while the second treatment produces changes in the degree of order of the weakly magnetic phase

Decomposition of the solid solution in a high-strength copper-base alloy
Rosenberg V.M.; Teplitskii M.D.; Fridman A.A.
Fizika Metallov i Metallovedenie Volume: 31 Issue: 6 Pages: 1320-2 Published: 01 1971

Using electron microscope examination and X-ray diffraction analysis, the authors investigated the decomposition of the solid solution in a Cu-base alloy containing 15.3% Ni, 1.9% Cr, 3% Mn and 3.4% Al. Ageing specimens of this alloy for 1.0 hr at 700degC led to the segregation of the solid solution into two isomorphic phases accompanied by the formation of a periodically modulated structure and precipitation of a third disperse phase. No transformation of this kind has been reported before

Susceptibility of Alnico alloys to thermomagnetic treatment
Povolotskii E.G.; Fridman A.A.; Titov V.S.
Fizika Metallov i Metallovedenie Volume: 32 Issue: 1 Pages: 44-51 Published: 01 1971

The authors investigated conditions of the manifestation of the effect of thermomagnetic treatment (TMT) in mono- and polycrystalline specimens of alloys Alnico of various compositions. It was shown that the susceptibility to TMT is a property of alloys in which the structural transformation (disperse decomposition beta 2rarrbeta+beta 2) is at the same time a magnetic transformation. There is therefore no direct relation between the Curie point of the starting phase beta 2 and the manifestation of the TMT effect. The fine characteristics of the decomposition texture for the case of complete and incomplete TMT effect were studied

Structure and properties of cupronickel-base age-hardening alloys
Rozenberg V.M.; Teplitskii M.D.; Fridman A.A.
Fizika Metallov i Metallovedenie Volume: 34 Issue: 2 Pages: 326-31 Published: 01 1972

The authors investigated the structure and properties of four alloys containing about 80% Cu, 16% Ni, and two or three minor alloying additions of Mn, Cr, and Al. In every case ageing was accompanied by decomposition of the solid solution into two isomorphous phases and formation of a periodic structure, particles of a third phase being precipitated in two of the alloys studied in which intense hardening was observed. It was concluded that the latter effect was a result of a combined influence of a periodic structure and the presence of third phase particles

Structure of Ticonal type alloys after quenching from temperatures of 800-850degC
Sumin V.I.; Fridman A.A.; Pashkov P.P.; et al.
Fizika Metallov i Metallovedenie Volume: 43 Issue: 3 Pages: 652-4 Published: March 1977

Analysis of X-ray diffraction patterns of a Ticonal type alloy YuNDK35T5 quenched from 800-850degC showed that the alloy after such a treatment consists of three phases, two phases only being present in specimens air-cooled from the same temperature. The existence of a three-phase state makes it possible to explain the phenomenon of `reversibility' of magnetic properties of alloys of the Ticonal type

Two- and one-dimensional modulated structure in the alloy Ticonal
Fridman A.A.; Pashkov P.P.
Fizika Metallov i Metallovedenie Volume: 48 Issue: 5 Pages: 1096-8 Published: Nov. 1979

Using X-ray diffraction analysis, the authors determined crystal lattice parameters of phases present in the alloy YuNDK35T5 in its three-phase state (produced by a thermomagnetic treatment at 800-830degC followed by water quench) and in the alloy YuNDK40T7 subjected to the same treatment. The latter alloy after treatments at 840 and 820degC had a two-dimensional three-phase modulated structure similar to that previously observed in the alloy YuNDK35T5 (Sumin et al., ibid., vol.43, p.652, 1977). However, X-ray diffraction data obtained for the alloy YuNDK40T7 subjected to the thermomagnetic treatment at 800degC indicated that in this case a one-dimensional two-phase modulated structure had been produced

Flux pinning centres in solid-state diffusion processed superconducting Nb ₃(AlGe) alloyed with Cu

Dukhovnii I.S.; Fridman A.A.; Korzhov V.P.; et al.
Physica Status Solidi A Volume: 62 Issue: 1 Pages: 123-8 16 Nov. 1980

The pinning centers in the tapes on the base of Nb 3(AlGe) alloyed by copper are investigated with transmission electron microscopy. The critical current density in thick (up to 8 mum) layers of Nb 3(AlGe) reaches the value of 3times10 9 A/m 2 at the magnetic field 5.5 T and 1.7times10 9 A/m 2 at the field 13.5 T. The main pinning centers in these samples are the second phase particles precipitated during the ageing type process. The relative contribution to the critical current of the different pinning centers (grain boundaries and second phase particles) is evaluated

Flux pinning centres in solid-state diffusion processed superconducting Nb ₃(AlGe) alloyed with Cu

Dukhovnyi I.S.; Korzhov V.P.; Fridman A.A.; et al.
Source: Metallofizika Volume: 3 Issue: 1 Pages: 43-51 Published: Jan.-Feb. 1981

Pinning centers are studied in composite bands on the base of the superconductive copper-alloyed Nb 3(Al, Ge) compound. Electron-microscopic studies in alloyed and nonalloyed bands allowed revealing the reason on the critical current Ic increases in bands with copper after low-temperature annealing (LTA). Measurements in the band critical current right after high-temperature heating and after LTA made it possible to determine a relative contribution of pinning centers of different kinds: grain boundaries of the compound and the second phase particle precipitation. The effect of LTA on the band microstructure and superconductive properties is studied. It is stated that the critical current density after LTA at 800 degC does not practically depend on the layer thickness in the Nb 3(Al, Ge) compound and is equal to ~2times10 5 A/cm 2 in a 55 kOe magnetic field

Formation of structure and magnetic properties for YuNDKT alloys by thermomagnetic treatment
Sergeev V.V.; Bulygina T.I.; Fridman A.A.
Metal Science and Heat Treatment Volume: 23 Issue: 3-4 Pages: 206-11 March-April 1981

Presents results of studying the dependence of magnetic properties and structure for YuNDKT alloys on the temperature of thermomagnetic treatment (TMT). The decomposition process for a supersaturated solid solution during TMT is considered with the use of a theoretical analysis for model structures. The effect of lattice type, morphology, and magnetic properties of phases in typical YuNDKT magnetic alloys with TMT is analysed

Investigation of a superconducting excitation system for a cryogenic rolling-mill motor

Veselovskii, A.S.; Dan'ko, V.G.; Klimenko, E.Yu.; Kruglin, V.A.; Novikov, S.I.; Rubinraut, A.M.; Fridman, A.A.

Soviet Electrical Engineering Volume: 54 Issue: 7 Pages: 124-6 Published: 1983

Original Source: Elektrotekhnika Volume: 54 Issue: 7 Pages: 69-71 Published: 1983

The peculiarities of a cryogenic rolling-mill motor require that a superconducting (SC) excitation winding for a cryomotor with multimember cryostatting system must be reliably stabilized for gaseous helium temperatures. The superconducting magnetic excitation system of a DC rolling-mill cryomotor which has several features that are occasioned by the construction of the motor and the operating regime of the mechanism is described