The frequency dependences of the real and imaginary parts of the complex dielectric constant in the spectral range of 0.069 to 5 eV and the temperature dependences of the resistance of the Crloo-xAl, (x 5 32 atyo Al) alloy system are investigated. I n alloys having 16 to 28 atyo of Al, a negative temperature coefficient of resistance, and a minimum metallic conductivity a(0) < < 1000 a-1 cm-l a dielectriza.tion of the optical properties is found characterized by strong anomalous concentration and frequency dependences of the dielectric function in the infrared frequency range. From the analysis of the behaviour of the optical o(w) and the static a(0) conductivities i t is concluded that the anomalies of optical and electrical properties result from the localization of free carriers near the Fermi level. MCCJIenOBaHbI YaCTOTHbIe 3aBHCHM09TH AefiCTBHTeiTbHofi 12 MHHMOfi saCTefi IcOMIlJleKCHO~ AH3JIeKTpPIeCKOa IlpOH12uaeMOCTEI B o 6 n a c~~ CneKTpa 0,069 HO 5 eV M TeMIIepaTypHbIe 3aRHCHMOCTH 3JIeKTpOCOnpOTHBJIeHHR CnJlaBOB CHCTeMbl Crloo-&& (X 5 32 atyo 4). AJIR CIIJIaBOB C 16 80 28 atyo Al, HMeIoWElX OTpHUaTeJlbHbIfi TeMIIepaTypHbIB K 0 3 @ @ H -UEl eHT COlIPOTHBJIeHHR EI MHHHMaJIbHYIo MeTaJlJIH9eCKYKl Il POBOLU4MOCTb O ( 0 ) < 1000 fi-lcm-', 06HapyMeHa HH3JIeHTpH3aq12FI OlITHseCKHX CBOfiCTB, Bblpa3HBlUaRCR B pe3HO aHOMaJIbHOfi EiOH4eHTpa4HOHHOfi H 9aCTOTHOfi 3aBHCHMOCTRX ,qH3JIeKTpH9eCKEIX @lHK4EIfi B HH#pa-IipacHoM ~~a n a s o~e YacToT. H3 a~a~1~3 a nosenemrr onTHsecKoii ~( w ) H cTaTmecrcot o(0) nposonmMocTefi AenaeTcR ~~K J I I O~~H H~, YTO aHoMamwi on'rmecmix II ~J I~K T~H Y~C K H X CBOfiCTB BbI3BaHbI JlOHaJI123aUHe~ CBO6OAHbIij[ HOcHTenefi ~6 .~1 1 2 3~ YPOBHR QepMH.

An electron diffraction study is made of a quenched Cr—25 at% Al alloy exhibiting anomalous physical properties. An intensive diffuse scattering, complicated in form, with intensity maxima belonging to the ordered β‐phase (Cr2Al) and the recently observed x‐phase is detected. The diffuse scattering, including intensity maxima from the β‐ und x‐phases, is prone to vanish regularly, namely, the zero‐intensity line is always perpendicular to the reciprocal‐space vector, and this indicates that the scattering arises from transversely polarized “soft” modes. An analysis of the reciprocal lattice of CrAl alloys permits the conclusion that the diffraction picture produced by the x‐phase may be described by the incommensurate ω‐phase known in the literature. The detected structure qualitatively explains anomalies in the physical properties of CrAl alloys.

No abstract

Microsteam turbine implementation for combustion engine exhaust gases heat recovery and subsequent acquisition of additional power is being investigated in many developed countries of the world. The results of such studies have already found application in some trucks. But this type of turbines is very weak in the Russian market. Turbine installation behind the combustion engine works under conditions of low volumetric flow of work fluid. This leads to a decrease in the height of the blade and vane wheels flow passage and an increase of the relative values of the gaps in the seals which are the reasons for the growth of the working fluid leakages. High degree of pressure reduction when selecting single-stage turbine leads to a supersonic velocity in the flow passage and an increase of the losses due to powerful shock waves. The efficiency of the turbine installation under these operating conditions is low and requires additional investigations. In this work, the working fluids which can give the greatest efficiency of the turbine installation were investigated. It was shown that not only thermodynamic but also hazardous and economic parameters must be taken into consideration. Working fluid with the high thermodynamic efficiency was compared with the one that profitable from economic point of view. The most appropriate substance was chosen and implemented in the microsteam turbine. The turbine stage which allows increasing economy and ecological compatibility of the combustion engine was developed and optimized by analytical methods.

The paper reports the expediency and substantiation of the necessity for the gradual transition to power units on supercritical stream parameters in world power engineering. Basic stages in the development of steam turbine manufacturing with supercritical steam parameters are considered. The parameter increase at the input makes a profound impact upon the design of a flowing part of turbines. To operate a great difference in enthalpies in a cylinder without changing stages number one has to modernize them and sometimes to change the design completely. In the paper there is considered the expediency of the application of axial highloaded stages developed by the Polytechnics of Leningrad (LPI). There are also described the stages of designing steam turbine plants with critical and supercritical steam parameters at the input in a turbine. As an example there is analyzed SKR-100-300 steam turbine with the initial steam parameters of 29.4MPa and 650S. The results of solution computations directed to the efficiency increase of a regulatory stage of K-300-240 steam turbine with supercritical parameters of 580C and 29.0 MPa are presented. The application as a profile of an impeller the blade design of LPI allows increasing turbine plant efficiency in a wide range of mode parameters and also reducing a general number of turbine stages.