Formation of the granular structure in the intermetallic compound Ni3Al in high-temperature synthesis under compression

The process of high-temperature synthesis of the Ni₃Al intermetallic compound under conditions of a thermal explosion of the 3Ni-Al powder mixture under compression is considered. Quantitative estimates of dispersion of the granular structure of the synthesized intermetallide are made within the framework of the mathematical model proposed in the present paper. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 3, pp. 64–70, May–June, 2006.     

High-temperature synthesis of the Ni<Subscript>3</Subscript>Al intermetallic compound under pressure

We investigate by experimental and numerical methods the high-temperature synthesis of the Ni₃Al intermetallic compound in the thermal explosion mode under the pressure of a powder mixture of nickel and aluminum of a stoichiometric composition. The calculated and experimental thermograms of self-propagating high-temperature synthesis are analyzed depending on the temperature of preliminary heating of the powder mixture and the magnitude of external pressure.     

Level of vitamins B in yeasts of the Saccharomyces species depending on the composition of culture media]

The qualitative and quantitative composition of water-soluble vitamins B in Saccharomyces yeasts cultivated on various nutrient media was studied by high-performance liquid chromatography. New strains of Saccharomyces oviformis Y-2635 and Saccharomyces vini F-5 yeasts grown in the nutrient medium with geothermal water differed in great biological value due to high intracellular concentrations of riboflavin, thiamine, nicotinic acid, and folic acid.     

Detecting hazardous sources of acoustic-emission signals using the estimated energy of clusters

A method for detecting hazardous sources of acoustic-emission (AE) signals by the level of their energy activity using clustering by digitized signal shape was considered. The influence of the distance between a source and an AE transducer on the energy of recorded AE signals was analyzed. The energy distribution median of signals in a cluster was proposed for evaluating the hazard of an AE signal source. The application of the developed method was tested based on the example of the analysis of AE inspection data on the welding of steel specimens with incomplete fusion and a crack at the root of a weld seam. This testing confirms the results of the fractographic inspection of a defective weld seam.     

A rapid method for monitoring the sodium thiocyanate content of aqueous solutions in the manufacture of polyacrylonitrile fibre

Conclusions A refractometric method for rapid analysis of sodium thiocyanate in technological PAN-fibre solutions has been developed. A procedure has been devised and recommended for introduction for performing measurements, which has been metrologically certified and has been tested in analytical control of PAN fibre.Saratov Nitron PO. Translated from Khimicheskie Volokna, No. 2, pp. 55–57, March–April, 1992.     

Self-similar solution of a hydraulic fracture problem for a poroelastic medium

A solution of a coupled problem on the propagation of a hydraulic fracture (HF) with respect to the processes of deformation and flow in a poroelastic medium is considered. The fracture is formed and developed under the impact of a Newtonian fluid pumped into it through a well. The sets of self-similar solutions are constructed. These solutions are used to describe the evolution of a penny-shaped shallow fracture in a poroelastic medium with a uniform pressure inside the fracture. This work is a part of the HF publication series, which are based on splitting the original equations into components in accordance with the incomplete coupling principle.     

Incompletely Coupled Equations of Hydraulic Fracturing

We study a three-dimensional coupled problem of the creeping flows of a viscous fluid in a hydraulic (and magmatic) fracture and the strain and flow in the external poroelastic medium induced by them. The process is governed by injection fluid into a well. The flow in the fracture is described by the Stokes hydrodynamic equations in the approximation of the lubricating layer. The external problem is described by the equations of poroelasticity. An ordered sequence of interdependent geomechanical processes occurring under hydraulic (and magma) fracturing is established. In other words, the solution of the coupled problem of hydraulic fracturing is reduced to the sequential solution of three incompletely coupled problems representing the motion in the fracture, as well as the elastic and flow processes in the host rock. The proposed transformation is of practical importance for petroleum geophysics; it allows conducting a more profound in-depth study of the nonisothermal and physicochemical phenomena for occurring in the above-mentioned fractures; and it provides a better insight into the physics of the associated processes.     

Acoustic-emission study of the possibilities of localizing flaws of a welded joint during cooling

A method of localizing acoustic-emission signals from flaws of a welded joint during its cooling is considered. Aluminum and titanium inserts were used to simulate flaws of the welded joint. The developed technique of clustering made it possible to exclude noise accompanying the processes of welding and cooling the welded joint. The welded specimens were tested on an MTS-50 loading machine. At the finishing stage, specimens with double-sided welded joints containing titanium inserts were subjected to metallographic analysis.     

Clustering of sources of acoustic-emission signals by the leading-edge rise rate

It is shown that the method of clustering by the leading-edge rise rate of the envelope of an acoustic-emission (AE) signal makes it possible to reduce the time of calculation of the coordinates of flaws as compared to the clustering by shape. The developed technique realizes the on-line localization of massive flows of AE signals with an accuracy sufficient for practical application. The practical parameters of using the method for operation on a steel sheet with a simulator obtained for a statically loaded duralumin specimen and for welding of steel specimens with aluminum and titanium inserts are considered.     

Electrothermopolarization influence upon the structure and properties of a composition on the basis of polyethylene and Co(AlO<Subscript>2</Subscript>)<Subscript>2</Subscript>

The influence of electrothermopolarization on the structure and properties (electret, strength) of a composition on the basis of polyethylene and a low-molecular dye Co(AlO₂)₂ was investigated. It was experimentally established that the additive Co(AlO₂)₂ changes the polyethylene structure. As a result, the electret properties of the composition change. Correlation of the strength properties with the changes of the degree of the crystallinity of the polyethylene was observed.