A positron annihilation study of defect accumulation in phosphorus- and titanium-alloyed austenitic stainless steels under electron irradiation at room temperature

The effect of phosphorus and titanium additions on the accumulation of vacancy defects in Cr16Ni15Mo3 austenitic stainless steels under electron irradiation at room temperature is studied by positron annihilation spectroscopy. It is shown that, at this temperature, phosphorus has no noticeable effect on the accumulation of vacancy defects. This is due to the low mobility of vacancies and the low concentration of impurities. Titanium, due to its high concentration, enhances the accumulation of vacancy defects during irradiation, but this effect is weak.

A peculiarity of the magnetization of a ferromagnet by an alternating field

It has been experimentally established that the demagnetizing field of the magnetic poles formed at the ends of an open ferromagnetic cylinder decreases with increasing frequency of the magnetizing field due to a decrease in their size under the influence of the surface effect. For this reason, as the frequency of the magnetizing external field increases, the internal field in a ferromagnetic cylinder near the surface approaches it in amplitude. In addition, it has been found that the field on the surface of a ferromagnetic rod magnetized by an alternating field significantly exceeds the latter in strength with increasing frequency of this field.

Implants and bone technology with the use of doped calcium carbonate phosphates

The possibility of obtaining an alloplastic biomaterial for the implant based on doped calcium carbonate-phosphates and polycaprolactone is studied. Nanocrystalline calcium carbonate-phosphate doped with cations of iron, magnesium, potassium, zinc, manganese, and silicon intended for bone repair by drug delivery is investigated. Histological studies have revealed that samples after 60 days in a living organism are covered by a connective tissue capsule. The formation of blood vessels and nerve endings is observed in the capsule.

Neural network modeling of the rheology of the AlMg6 alloy under the dispersoid barrier effect and the inhibition of dynamic relaxation processes

The paper deals with a neural network to model the flow stress of the AlMg6 alloy at temperatures ranging between 300 and 500 C and strain rates from 1 to 25 s−1. In this temperature–strain-rate range, the movement of free dislocations is blocked and dynamic relaxation processes are inhibited. The results of training the neural network and its verification at a temperature not used in the training show that neural networks with a single hidden layer can correctly approximate and predict the rheological behavior of the AlMg6 alloy for the studied temperature–strain-rate range of deformation.

In memory of Eduard Stepanovich Gorkunov

25 октября на 76-м году скончался инициатор создания и главный редактор журнала «DIAGNOSTICS, RESOURCE AND MECHANICS of materials and structures» Эдуард Степанович Горкунов, академик Российской академии наук, профессор, доктор технических наук.

Production of pure nickel alloys doped with sulfur and phosphorus

A procedure for alloying nickel with sulfur and phosphorus by diffusion and homogenizing annealing is described using the example of pure nickel (RRR at 600). A scheme of the installation for alloying from the gas phase is described. The possibility of uniform alloying with sulfur and phosphorus of samples and material in the form of plates or foils with a thickness of 0.2 mm or thinner at a concentration ranging between 0.001 and 0.08) at. % is shown. Diffusion annealing is carried out after heating and pumping out in a high vacuum and without contamination, in a quartz volume containing sulfur or phosphorus vapors at a temperature of 1100 to 1200 °C. By choosing the ratio of the masses of the alloyed material and the corresponding filling of sulfur or phosphorus, it is possible to predict in advance the resulting concentration of impurities with a sufficient time of annealing. The impurity concentration is uniform in volume within ten percent. Modeling and control annealings with the measurement of the residual resistivity of the control samples allows you to evaluate the results obtained.

A precision low-frequency Analog-to-Digital converter for advanced systems of technical diagnostics and nondestructive testing

The main results of the development of a precision low-current meter based on a nonlinear ADC are presented. It is shown that the application of the method of nonlinear analog-to-digital conversion and a controlled voltage level at the non-inverting input of an integrating operational amplifier allows both high sensitivity and a wide dynamic range with a small spread of output codes. The use of the laboratory sample of the meter for cyclic tensile testing of steel specimens is described.

On numerical methods for constructing benchmark solutions to a nonlinear heat equation with a singularity

The paper deals with the construction of exact solutions to a nonlinear heat equation with degeneration in the case of the zero value of the required function. Generically self-similar solutions and traveling wave solutions are considered, the construction of which reduces to solving Cauchy problems for a nonlinear second-order ordinary differential equation with a singularity before the higher derivative. Two approaches are proposed to solve the Cauchy problems: the analytical solution by the power series method and the numerical solution by the boundary element method on a specified segment. A complex computational experiment is carried out to compare the above two methods with each other and with the finite difference methods, namely the Euler method and the fourth-order Runge-Kutta method. Power series segments are used on the first step of the finite difference solutions in order to resolve the singularity. The comparison of the application domains, the accuracy of the solutions and their dependence on the parameters of a certain problem shows that the boundary element method is the most universal, although not the most accurate for some particular examples. The conclusions drawn allow us to construct benchmark solutions to verify the approximate solutions of the nonlinear heat equation by various methods in a wide range of parameter values.

Formation of a system of indicators for evaluating the characteristics of asynchronous electric motors at their life cycle stages

The article focuses on the development and formation of a system of indicators for assessing the characteristics of asynchronous electric motors (AEMs) at various life cycle stages. The problem is solved on the basis of the topological approach to the analysis of heterogeneous electromechanical systems. The life cycle of AEM and the tasks of its information support are described. The flows of diagnostic information are analyzed. Indicators for assessing the health of AEDs at various stages of their life cycle are proposed.

Applying an updated method of markers to defining transient force impact under multiphase flowing

Numerical simulation of transient hydrodynamic forces from shaped gas cavities formed in liquid under active interaction of liquid and a jet source of high-temperature gas and intensive heat and mass transfer is performed. To solve the task, a method of coarse particle markers with, as opposed to the classical one, an additional stage, when moving boundaries of different media in cells with interfaces of these media are as if stitched, is updated. In addition, problems of inter-media heat and mass transfer by condensation and evaporation are simultaneously solved. The predicted results are compared with the experimental data. Validation and verification are performed by comparing the analysis results with the experimental data. The applicability of the updated method of coarse particle markers to defining transient force impact under multiphase flowing is demonstrated.