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Five independent adiabatic elastic tensor components c ij of single-crystal Hf (0.3% Zr) have been precisely measured in the range 78–300 ( c 11 and c 33) or 78–160 K ( c 12, c 13, and c 44) at 50 MHz using an ultrasonic pulse technique. The corresponding linear absorption coefficients α ij ( T) have been measured in the same temperature ranges. The c ij data have been used to determine adiabatic compressibilities β∥ and β⊥, and Young’s moduli E ∥ and E ⊥ along and across the c axis, respectively. Near 140 K, we have revealed an anomaly in c 33( T) due to changes in the phonon spectrum of single-crystal α-Hf. The observed anomalies in temperature-dependent α11 and α33 are tentatively attributed to grown-in dislocations. [ABSTRACT FROM AUTHOR]

We analyze the results of investigations of the in-service defects of heat-exchange tubes of steam generators of WWER reactors and the metal of pipelines and welded joints. The specific features of damage to heat exchangers and welded joints of the collectors with branch pipes of the bodies steam generators are analyzed. The causes of degradation of materials of the secondary coolant circuit are established. The directions of subsequent investigations aimed at increasing the reliability and duration of service life are outlined. [ABSTRACT FROM AUTHOR]

The structure of single crystals of the NV-4 nickel alloy containing 32–36 wt % W is investigated. The temperature gradient at the crystallization front and the velocity of the crystallization front are the variable parameters of directional crystallization. The degrees of structural perfection of the single crystals grown under different conditions are compared. The crystallization parameters providing growth of single crystals that have high structural perfection and can be successfully used as seeds for the growth of single-crystal blades are determined. Typical defects formed upon directional crystallization of single crystals of the Ni–W (35 wt %) alloy are examined. The studied defects are classified, and the factors responsible for the disturbance of the single-crystal structure are analyzed. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The structure and microhardness of single crystals of nickel–tungsten alloys containing 25–36 wt % W are investigated. The temperature gradient at the crystallization front and the velocity of the crystallization front are the variable parameters of directional crystallization. It is found that, when the velocity of the crystallization front is 4 mm/min, the morphology of the cellular structure of the single crystals grown from nickel–tungsten alloys changes from square cells to hexagonal cells at a tungsten content of greater than or equal to 31 wt %. As the velocity of the crystallization front increases to 10 mm/min, no morphological transition occurs. It is shown that impurities play an important role in the formation of a cellular structure with cells of different types. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]