Physical fundamentals of thermomechanical processing in ultrafine-grained metallic materials manufacturingА.I. Rudskoi, G.Е. Коdzhaspirov, J. Kliber, Ch. Apostolopoulos & D.A. Kitaeva
The processing of metallic materials through the application Thermomechanical Processing (TMP) has now become of major importance in the world research and industrial companies. A great attention is paid to study of mechanism TMP applied to different techniques and technological processes providing ultrafine-grained state of metal materials including submicro – and nanocrystalline ones. The main development in terms of obtaining bulk metallic materials received in the recent years, various schemes of TMP of metallic materials,...
Additive Manufacturing (AM) of copper and its alloys is a promising way to produce parts with complex geometries without tooling. One of the AM processes is Selective Laser Melting (SLM) technology that uses a laser beam to fuse powder layers to obtain a final part. Laser processing of copper is considered to be a challenging task due to its high thermal conductivity and poor laser absorptivity. In the present work, Cu-Cr-Zr-Ti alloy powder has been...
Transformation kinetics of undeformed and deformed austenite during continuous cooling has been investigated on several industrial steels. Dimensions of both prior austenite grains and ferrite grains in ferrite-pearlite structures obtained for various states of parent austenite and cooling rates were determined. Based on the obtained experimental data a physically motivated model is formulated for the ferritic transformation with allowance for the effects of deformation and concurrent recovery of austenite. Under consideration is the deformation influence...
3D finite element, connected with orthogonal finite functions, in modeling and investigation of elastic homogeneous and heterogeneous materialV.L. Leontiev & I.V. Efremenkov
A novel 2D finite element (FE) associated with orthogonal finite functions (OFF, orthogonal splines) was developed for the ANSYS software and was tested early. The expansion of this method is presented here. The novel 3D FE, connected with 3D OFF is proposed for modeling and investigation of the stress-strain state of homogeneous and heterogeneous elastic bodies. The accuracy of the solutions obtained with this 3D FE is as high as for the classic ANSYS 3D...
We have systematized possible ways of forming the isomers of midi-fullerenes, namely C22, C24, C26 and C28. There are three the most natural mechanisms of their obtaining: embedding carbon dimers into initial fullerenes; fusion of carbon cupolas having the same symmetry; fusion of fullerenes having compatible symmetry. The minimum energy fullerenes are obtained through the use of the first mechanism. It is worth noting that these fullerenes conserve the topological three-fold symmetry. At the same...
We have systematized possible ways of forming the isomers of midi-fullerenes, namely C30, C32, C34 C36, C38 and C40. Similar to the isomers of midi-fullerenes from C20 to C28, there are three the most natural mechanisms of their formation: 1) Embedding carbon dimers into initial fullerenes; 2) Fusion of carbon cupolas having the same symmetry; and 3) Fusion of fullerenes having compatible symmetry. The energies of the fullerenes calculated through the use of molecular mechanics...
The characteristics of terahertz (THz) irradiation generated by a silicon nanosandwich structure under the conditions of a stabilized drain-source current are demonstrated. The frequency of irradiation arising from the quantum Faraday effect is determined by the parameters of microcavities embedded in the edge channels of a silicon nanosandwich structure confined by the negative-U centers. The obtained characteristics of a compact THz irradiation source determine the basis for highly effective medical applications.
A new dynamical equation is derived by substituting the Schrödinger-LangevinKostin equation into the definition for the Wigner function, it can be called the quantumclassical Wigner-Langevin equation. The proposed equation contains partial derivatives for time and phase space variables of the Wigner function, its coefficients are spatial derivatives of potentials that take into account friction, white noise and external influence. The transition to the classical regime of motion is also discussed.
Two designs of a composite marine hatch cover were developed on the basis of the design of a steel one. One of the proposed designs features composite structure made by means of manual lay-up technology, and the other one is based on a truss composite structure which can be produced by rod winding process. Selection of the most rational materials and design parameters was carried out on the basis of finite element simulations and use...
Possible ways of nuclear synthesis in the range from hydrogen to boron are studied. The geometric model of these nuclei is suggested. The basis for this model is the analogy between tetrahedral fullerene C4 and helium 2He4 . It is assumed that a nucleus of helium 2He4 has the form of a tetrahedron, where: 1) All the apices are equivalent and therefore they are protons, 2) Each neutron in a nucleus decomposes into a proton...
The nuclear geometry has been developed by analogy with the fullerene geometry. On the base of this geometric approach, the structure of carbon isomers and isotopes, which can be obtained by means of nuclear synthesis, has been designed. The mechanisms of possible nuclear reaction are discussed. Carbon is an unusual element. It has four isomers of different symmetry: three-fold, six-fold and tetrahedral ones, two being stable and one halfstable. The isotopes of carbon inherit the...
Представлены результаты экспериментальных исследований высокотемпературного разложения аммиака в присутствии фторида водорода на катализаторе торгового наименования ГИПХ-55 на основе фторида магния и хлорида хрома. Определены константы скорости реакций и значения энергии активации. Данные экспериментальные результаты могут быть положены в основу промышленной технологии получения безводного фтористого водорода из гексафторкремниевой кислоты, одного из основных побочных продуктов производства фосфатных удобрений.
Peter the Great St. Petersburg Polytechnic University41
University of Patras2
Saint-Petersburg State University of Technology and Design1
Montreal Economic Institute1
Graz University of Technology1
Riga Technical University1
Tashkent Institute of Irrigation and Agricultural Mechanization Engineers1
Ulyanovsk State University1