Investigation of the characteristics of thermionic converters with a Mo (110) single-crystal collector with Ion-implanted oxygen

Institute of Nuclear Reactors, Russian Scientific Center "Kurchatovskii Institut." Translated from Atomnaya énergiya, Vol. 76, No. 2, pp. 151–152, February, 1994.     

Processing and Deformation Behavior of Gamma TiAl Alloys with Fine-Grained Equiaxed Microstructures

This paper describes how a submicrocrystalline structure can be produced by isothermal deformation of cast and powder metallurgy -TiAl-based alloys at temperatures 1000°C and below using relatively inexpensive nickel-based superalloy die tooling. A detailed analysis of the effects of initial microstructure, chemical compositions, conditions of heat treatment and hot working on the formation of a homogeneous fine-grained microstructure in -TiAl-based alloys is presented.     

Adsorption and emission features of collectors of thermionic energy converters in the case of mass transfer in the interelectrode gap

Translated from Atomnaya Énergiya, Vol. 69, No. 3, pp. 196–197, September, 1990.     

Manifestation of the Portevin-Le Chatelier effect in the Kh20N80 alloy

It has been found that the single-phase nickel alloy Kh20N80 demonstrates discontinuous flow in the range of deformation temperatures of 300–650°C. It is shown that the discontinuous flow of this alloy possesses signs of the Portevin-Le Chatelier effect, strong localization of deformation, and negative strain-rate sensitivity of the flow stress. Furthermore, three specific features of the discontinuous flow of the Kh20N80 alloy have been revealed: (1) the “normal” dependence of the critical degrees of the onset of the discontinuous flow of ?_cr on the strain rate; (2) the “inverse” temperature dependence of ?_cr; and (3) the positive temperature dependence of the flow stress. These special features appear to be caused by the formation of a short-range-order structure, which occurs in this alloy at temperatures of approximately 350–500°C.     

Cesium vapor source based on gas-regulated heat pipe for an autonomous thermionic egc

The results of work on the development of a source of cesium vapor for a thermionic EGC based on a gasregulated heat pipe and investigations of its basic technical characteristics in the cesium vapor range 30–700 Pa are presented. It is shown that the evacuation capacity and zero response time of a gas-regulated heat pipe based vapor source and the possibility of continuously monitoring the cesium vapor pressure via the temperature in the adiabatic zone and the pressure in the gas reservoir are all effective.     

Excitons in single and double GaAs/AlGaAs/ZnSe/Zn(Cd)MnSe heterovalent quantum wells

Exciton photoluminescence spectra, photoluminescence excitation spectra, and magnetophotoluminescence spectra of single (GaAs/AlGaAs/ZnMnSe) and double (GaAs/AlGaAs/ZnSe/ZnCdMnSe) heterovalent quantum wells formed by molecular beam epitaxy are studied. It is shown that the exciton absorption spectrum of such quantum wells mainly reproduces the resonant exciton spectrum expected for usual quantum wells with similar parameters, while the radiative exciton recombination have substantial distinctions, in particular the additional localization mechanism determined by defects generated by heterovalent interface exists. The nature of these localization centers is not currently clarified; their presence leads to broadening of photoluminescence lines and to an increase in the Stokes shift between the peaks of luminescence and absorption, as well as determining the variation in the magnetic g factor of bound exciton complexes.