Дослідження електричної корозії міді і алюмінію та аналіз кінетики зникнення інтерметалідів у системі Cu-Al

Copper and aluminum electric corrosion is investigated experimentally. It is founded that copper corrosion is higher than aluminum corrosion. Intermetallics disappearance rate in Cu-Al system is analyzing theoretically. Literature experimental data are used for analysis.Експериментально досліджено електричну корозію міді та алюмінію. Оримано такий результат: електрична корозія міді значно швидша, ніж електрична корозія алюмінію, тому тонке алюмінієве покриття товщиною близько 1 мікрометра на мідних дротинках може уповільнити корозію міді у приладах мікроелектроніки. Теоретично проаналізовано процес зникнення інтерметалідів у системі Cu-Al. Для аналізу були використані літературні експериментальні дані

MATHEMATICAL METHODS OF THE INTERMEDIATE PHASE GROWTH DESCRIBING

A model of describing the diffusion phase growth from point sources inside polycrystals grains is regarded. Analytical method to solve differential diffusion equations for such model is suggested. Analytical method to solve differential diffusion equations of describing the growth of the phase wedge during the intermetallic compound formation with a narrow concentration range of homogeneity in bicrystals is proposed. Parabolic, cubic, fourth power diffusion regimes for different scales from nanometers to micrometers and millimeters are analyzed.Key words: diffusion, reaction, phase growth law, intermetallic compounds, grain boundaries.кандидат фізико-математичних наук, доцент Ярмоленко М. В. Математичні методи опису росту проміжної фази / Київський національний університет технологій та дизайну, Україна, ЧеркасиРозглядається модель, яка описує кінетику утворення інтерметалевої фази з точкового джерела всередині полікристалічних зерен. Пропонується відповідний аналітичний метод розв’язування диференціального рівняння такої моделі. Пропонується аналітичний метод розв’язування диференціального рівняння, яке описує кінетику утворення інтерметалевої фази вздовж границі між зернами з одночасним проникненням у самі зерна. Аналізуються дифузійні режими (параболічний, кубічний, четвертого степеня) для різних масштабів: від нанометрового до мікрометрового і міліметрового.Ключові слова: дифузія, реакції, закон росту фази, інтерметалеві сполуки, міжфазні границі.кандидат физико-математичних наук, доцент Ярмоленко М. В. Математические методы описания роста промежуточной фазы / Киевский национальный университет технологий и дизайна, Украина, ЧеркассыРассматривается модель, которая описывает кинетику образования интерметаллического соединения из точечного источника внутри поликристаллических зерен. Предлагается соответствующий аналитический метод решения дифференциального уравнения такой модели. Предлагается аналитический метод решения дифференциального уравнения, которое описывает кинетику образования интерметаллического соединения вдоль границы между зернами с одновременным проникновением в сами зерна. Анализируются диффузионные режимы (параболический, кубический, четвертой степени) для разных масштабов: от нанометрического до микрометрического и миллиметрового.Ключевые слова: диффузия, реакции, закон роста фазы, интерметаллические соединения, межфазные границы

THE KIRKENDALL EFFECT AND PHASE FORMATION KINETICS DURING SOLID STATE REACTIONS

In the article it was proved theoretically and experimentally that the interface curvature can either accelerate or slow down the Kirkendall shift and the diffusion phase layer growth in cylindrical and spherical samples when compared with a planar sample depending on the average phase concentration only. It is shown that internal stress, arising due to dilatation during phase growth, can either accelerate or slow down the growth in addition to the above-mentioned effect, depending on the difference in mobilities of different atoms within each phase and independently on the sign of dilatation.У статті доведено теоретично та підтверджено експериментально, що кривизна міжфазної границі може як пришвидшувати, так і уповільнювати дифузійне утворення шарів фаз у циліндричних та сферичних зразках та зміщення Кіркендалла в залежності лише від середньої концентрації однієї з речовин. Додатково впливати на кінетику можуть також внутрішні механічні напруги, які виникають у процесі фазоутворення. В статье доказано теоретически и подтверждено экспериментально, что кривизна межфазной границы может как ускорять, так и замедлять диффузионное образование слоев фаз в цилиндрических и сферических образцах и смещение Киркендалла в зависимости только от средней концентрации одного из веществ. Дополнительно влиять на кинетику могут тоже внутренние механические напряжения, которые возникают в процессе фазообразования.

The Practice of Using Game Models to Analyze the Risks of the Operation Processes of Agricultural Enterprises Based on the Indicators of Components of Effectiveness

The article proposes the methodology of practical use of game theory for analyzing of risks of subprocessions of operational processes of agricultural enterprises on the basis of models of components of effectiveness by Burennikova (Polishchuk) – Yarmolenko and relevant indicators. The methodology is considered on the example of processes of formation of gross incomes at five agricultural enterprises of grain products subcomplex as subprocesses of operational processes of these enterprises. A certain payment matrix for the case of non-strategic game (playing with nature) was built. A gains matrix would generate a risk matrix. Two risk matrices are obtained, depending on the two formulas according to which the elements of these matrices are calculated. According to the data of these two risk matrices, the maximum risk values are found in each row, and two corresponding column matrices are drawn from these values. On the basis of the mentioned column matrices, a ranking of risks of functioning of the considered enterprises is carried out. The article researches the risks of functioning of enterprises in terms of effectiveness. Similarly, one can research the mentioned risks from the standpoint of efficiency

Dynamics of combined electron beam and laser dispersion of polymers in vacuum

The mechanisms of the impact of the laser assisting effect on the dispersion kinetics and on the structure of the deposited layers in electron beam dispersion of a polymer target were analyzed. The proposed model and analytical expressions adequately describe the kinetic dependence of the polymer materials dispersion rate in a vacuum on the intensity of laser processing of their dispersion zone

Detection of Polynitro Compounds at Low Concentrations by SERS Using Ni@Au Nanotubes

The identification of high-energy compounds in trace concentrations not only in the laboratory, but also in field conditions is of particular interest. The process should be clear, easy, and well-recognizable. We formed SERS-active substrates by using elongated nickel nanotubes synthesized by electrochemical deposition in the pores of ion-track membranes and coated them with gold for further application in the detection of low concentrations of analytes. The substrates were characterized using various techniques to determine the morphology of the nanotubes and modifying gold layer. The possibility of obtaining two types of gold-layer morphology was shown: in the form of a smooth film up to 20–50 nm thick and a coating with nanoneedles up to 250 nm long. The electric fields around the nanotubes were simulated at a laser wavelength of 532 nm to demonstrate the influence of the gold-layer morphology on the field distribution. The “needle” morphology was chosen to form the most effective SERS-active substrates for detection of low concentrations of aromatic polynitro compounds. The spectral peaks were identified by comparing the model and experimental Raman spectra at concentrations down to 10−5 M. Within this limit, all peaks (“fingerprints” of the substance) were clearly distinguishable. © 2022 by the authors.Ministry of Education and Science of the Russian Federation, Minobrnauka: AAAA-A20-120061890084-9; Russian Science Foundation, RSF: 21-72-20158Works on theoretical modeling were carried out within the framework of the State Contract of the Moscow Pedagogical State University (MPGU) “Physics of the perspective materials and nanostructures: basic researches and applications in material sciences, nanotechnologies and photonics” supported by the Ministry of Science and Higher Education of the Russian Federation (AAAA-A20-120061890084-9). S.B. and E.K. (Elizaveta Kozhina) are members of the scientific school SS-776.2022.1.2. Works on NTs fabrication and characterization were supported by the Russian Science Foundation, grant number 21-72-20158 (NTs as tool for magneto-mechanical treatment)

Кінетика росту конуса проміжної фази вздовж дислокаційних трубок всередині зерен полікристала

Dislocation-pipe diffusion (DPD) becomes a major contribution to device failure in microelectronic components at working temperatures. Usually, the simple random walk law for diffusion (Type C kinetics t1/2) is employed to calculate of DPD coefficients. The article presents an analytically solvable model of describing the diffusion phase cone growth along dislocation pipes inside polycrystal grains involving outflow from dislocation lines (Type B kinetics). Correlative analytical method to solve differential diffusion equations for such model is suggested. Competition between phase cone growth along dislocation lines involving outflow and phase wedge growth along grain boundaries (GBs) involving outflow is analyzed. It is shown that while phase wedge growth law along GBs is the Fisher regime t1/4, phase cone growth law along dislocation lines is another diffusion regime t1/6 . Real experimental data are analyzed using such diffusion regime. It is shown that it is possible to calculate DPD coefficients not only for the phase cone formation, but for migration of atoms along dislocations and self-diffusion along dislocation pipes too

A Further Insight Into Spherical Indentation: Ring Crack Formation In A Brittle La0.8Sr0.2Ga0.8Mg0.2O 3 Perovskite

It is known that theoretical considerations of fracture under loading by a spherical indenter are based on the concept of pre-existing cracks. However, nucleation and growth of the critical crack could occur during indentation, as happens during microcracking. The goal of the presented research is to develop a new concept of fracture under spherical indentation in a brittle elastic material taking into account the possibility of critical crack nucleation and growth during loading. La0.8Sr0.2Ga0.8Mg 0.2O3 (LSGM) perovskite has been chosen as a polycrystalline elastic low fracture toughness ceramic to perform indentation using a tungsten carbide spherical indenter. Experimental measurements of ring crack radii for well-polished LSGM cannot be explained within the framework of the pre-existing crack hypothesis. The local risk calculated using the concept of pre-existing cracks gives a most probable range of ring crack radii that does not match the radii measured experimentally. However, the local risk calculated using the assumption of critical crack nucleation and formation during spherical indentation results in a most probable range of ring crack radii which exhibits good agreement with the experimental data. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved