ODS+Hf and AISI 316L steel surface variations at high laser intensity, 1013 W/cm2, in air and vacuum: comparative study

The behavior of Oxide Dispersion Strengthened (ODS) steel with addition of hafnium, as well as AISI 316L steel, at high laser intensity of ~1013 W/cm2 in ambiences of air and vacuum, was studied. Irradiation source was Ti:Sapphire laser operating at 804 nm and pulse length of ~65 fs. Morphological and chemical studies were considered, thus that: (i) given laser intensity induced damages on both steels with the damage being more prominent on AISI 316L steel; (ii) various surface features were present, such as coral-like structure and Laser Induced Periodic Surface Structures (LIPSS), with LIPSS being dominant on the surface; (iii) the interaction was accompanied by generation of plasma above the target, and (iv) chemical analysis has shown that surface elemental content also depends on the ambience used.SPIG 2022 : 31st Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers and abstracts of invited lectures, topical invited lectures and progress reports; September 5-9,2022, Belgrad

Mechanical and tribological properties of aluminium incorporated with amorphous Ni60Nb40 particles

844-852In this paper, development and characterization of pure aluminium (Al) reinforced with metallic amorphous Ni60Nb40 particles has been presented. Ni60Nb40 amorphous alloy reinforcement powder has been incorporated within Al-metal powder to produce Al-Ni60Nb40 composite. The composite has been sintered using bidirectional microwave sintering technique. Structure, indentation/tensile/compressive behaviour and tribological properties of the produced Al-10% Ni60Nb40 have been evaluated. It has been found that the: (i) reinforcement have retained the amorphous structure, (ii) reinforcement have distributed uniformly in the matrix and (iii) interface between the Al-matrix and the amorphous reinforcement has been free of reactive products. Upon comparison of mechanical properties with pure aluminium, the synthesized composite has showed significant enhancement in microhardness, tensile and compressive yield strengths. Under dry sliding wear condition, the composite has showed lower wear rates and lower coefficient of friction. The observed improvement in the composite behaviour has been explained using the processing-microstructure-mechanical properties correlation

Mechanical and tribological properties of aluminium incorporated with amorphous Ni60Nb40 particles

In this paper, development and characterization of pure aluminium (Al) reinforced with metallic amorphous Ni60Nb40 particles has been presented. Ni60Nb40 amorphous alloy reinforcement powder has been incorporated within Al-metal powder to produce Al-Ni60Nb40 composite. The composite has been sintered using bidirectional microwave sintering technique. Structure, indentation/tensile/compressive behaviour and tribological properties of the produced Al-10% Ni60Nb40 have been evaluated. It has been found that the: (i) reinforcement have retained the amorphous structure, (ii) reinforcement have distributed uniformly in the matrix and (iii) interface between the Al-matrix and the amorphous reinforcement has been free of reactive products. Upon comparison of mechanical properties with pure aluminium, the synthesized composite has showed significant enhancement in microhardness, tensile and compressive yield strengths. Under dry sliding wear condition, the composite has showed lower wear rates and lower coefficient of friction. The observed improvement in the composite behaviour has been explained using the processing-microstructure-mechanical properties correlation

Mathematical Modeling of the Concentrated Energy Flow Effect on Metallic Materials

Numerous processes take place in materials under the action of concentrated energy flows. The most important ones include heating together with the temperature misdistribution throughout the depth, probable vaporization on the surface layer, melting to a definite depth, and hydrodynamic flotation; generation of thermo-elastic waves; dissolution of heterogeneous matrix particles; and formation of nanolayers. The heat-based model is presented in an enthalpy statement involving changes in the boundary conditions, which makes it possible to consider melting and vaporization on the material surface. As a result, a linear dependence of penetration depth vs. energy density has been derived. The model of thermo-elastic wave generation is based on the system of equations on the uncoupled one-dimensional problem of dynamic thermo-elasticity for a layer with the finite thickness. This problem was solved analytically by the symbolic method. It has been revealed for the first time that the generated stress pulse comprises tension and compression zones, which are caused by increases and decreases in temperature on the boundary. The dissolution of alloying elements is modeled on the example of a titanium-carbon system in the process of electron beam action. The mathematical model is proposed to describe it, and a procedure is suggested to solve the problem of carbon distribution in titanium carbide and liquid titanium-carbide solution in terms of the state diagram and temperature changes caused by phase transitions. Carbon concentration vs. spatial values were calculated for various points of time at diverse initial temperatures of the cell. The dependence of carbon particle dissolution on initial temperature and radius of the particle were derived. A hydrodynamic model based on the evolution of Kelvin-Helmholtz instability in shear viscous flows has been proposed to specify the formation of nanostructures in materials subjected to the action of concentrated energy flows. It has been pointed out for the first time that, for certain parameters of the problem, that there are two micro-and nanoscale peaks in the relation of the decrement to the wavelength of the interface disturbance

Microbial-environmental interactions reveal the evaluation of fermentation time on the nutrient properties of soybean meal

Microbial fermentation techniques are often used to improve their quality, where the keys are fermentation strains and fermentation time. This study studied the interaction between microbiota and environmental (or nutritional) factors and microbiota at different fermentation times to determine the most appropriate time, using lactic acid bacteria as fermentation strains. It can be concluded that fermentation improved the nutritional value of soybean meals. In the early stages of fermentation, debris in soybean meal highly proliferated and destabilized the microbial community, while pH and nutritional conditions played an important role in helping its stabilization. In addition, we must pay attention to the interspecific interactions of microorganisms, which makes it easy to understand how the microbial community maintains community stability. A 4-day fermentation of soybean meal with Lactobacillus is recommended

Microstructure and Mechanical Properties of Magnesium-Aluminium (Mg-Al) Alloys with High Aluminium Content (Al =10, 15, 20 wt. %)

184-189Magnesium-Aluminium (Mg-Al) alloys containing zinc or manganese are preferred choice in automobile and aerospace sectors. Aluminium, the major strengthening element in Mg-alloys is always added below its solid solubility limit of 12.5 wt.%. In the current study, Mg-Al binary systems with Al-content just below and above the solubility limit (Al = 10, 15 and 20 wt.%,) were developed and examined for their microstructural and mechanical behaviour. Microstructural studies showed the importance of Al-content in determining: (i) grain size reduction and (ii) distribution and amount of inter metallic phase. Mechanical property evaluation showed that the hardness increase was linearly dependent on Al-content, with Mg-20Al showing > 250% increase in hardness than commercial AZ91alloy. Mg-10Al showed 215% and 130% increase in yield and ultimate strengths respectively, and exhibited the best properties in terms of work of fracture, which is representative of the alloy’s toughness

Microstructure and Mechanical Properties of Magnesium-Aluminium (Mg-Al) Alloys with High Aluminium Content (Al =10, 15, 20 wt. %)

Magnesium-Aluminium (Mg-Al) alloys containing zinc or manganese are preferred choice in automobile and aerospace sectors. Aluminium, the major strengthening element in Mg-alloys is always added below its solid solubility limit of 12.5 wt.%. In the current study, Mg-Al binary systems with Al-content just below and above the solubility limit (Al = 10, 15 and 20 wt.%,) were developed and examined for their microstructural and mechanical behaviour. Microstructural studies showed the importance of Al-content in determining: (i) grain size reduction and (ii) distribution and amount of inter metallic phase. Mechanical property evaluation showed that the hardness increase was linearly dependent on Al-content, with Mg-20Al showing > 250% increase in hardness than commercial AZ91alloy. Mg-10Al showed 215% and 130% increase in yield and ultimate strengths respectively, and exhibited the best properties in terms of work of fracture, which is representative of the alloy’s toughness

DIRECTION OF PROPERTIES INCREASING OF CANTOR HEA

В настоящей статье выполнен обзор публикаций отечественных и зарубежных авторов по двум направлениям улучшения свойств сплава: CoCrFeNiMn легированием, выделениями и термообработкой, и использованием фазовых диаграмм Calphad. По первому направлению проанализирована роль легирования B, Vi, Al, V, Si, Nb; нановыделениями, различными режимами термической и деформационной обработки. Сделан вывод о необходимости проведения экспериментов по легированию ВЭС Zr и Nb, хорошо зарекомендовавших себя в упрочнении сталей. Показано, что создание и модифицирование свойств пятикомпонентных ВЭС возможно при использовании компьютерных программ Calphad, разработанных для расчета диаграмм состояния.This article reviews the publications of domestic and foreign authors in two areas of improving the properties of alloy: CoCrFeNiMn alloying, precipitation and heat treatment and the use of Calphad phase diagrams. In the first direction, the role of doping with B, Vi, Al, V, Si, Nb is analyzed; nanoprecipitations, various modes of thermal and deformation processing. It is concluded that it is necessary to conduct experiments on the alloying of HEA with Zr and Nb, which have proven themselves well in hardening steels. The creation and modification of the properties of fivecomponent wind farms is possible using the Calphad computer programs developed for calculating state diagrams.Работа выполнена при поддержке гранта РНФ 23-49-00015

Ambiguity Resolution for Phase-Based 3-D Source Localization under Fixed Uniform Circular Array

Under fixed uniform circular array (UCA), 3-D parameter estimation of a source whose half-wavelength is smaller than the array aperture would suffer from a serious phase ambiguity problem, which also appears in a recently proposed phase-based algorithm. In this paper, by using the centro-symmetry of UCA with an even number of sensors, the source’s angles and range can be decoupled and a novel algorithm named subarray grouping and ambiguity searching (SGAS) is addressed to resolve angle ambiguity. In the SGAS algorithm, each subarray formed by two couples of centro-symmetry sensors can obtain a batch of results under different ambiguities, and by searching the nearest value among subarrays, which is always corresponding to correct ambiguity, rough angle estimation with no ambiguity is realized. Then, the unambiguous angles are employed to resolve phase ambiguity in a phase-based 3-D parameter estimation algorithm, and the source’s range, as well as more precise angles, can be achieved. Moreover, to improve the practical performance of SGAS, the optimal structure of subarrays and subarray selection criteria are further investigated. Simulation results demonstrate the satisfying performance of the proposed method in 3-D source localization

Effect of applied load on welding stress at different time periods

In this study, pressure finite element welding simulations has been carried out. The welding model is a butt filled weld. The objective is to study the effect of pressure on welding stress of high strength steel at different time periods. From the study we can find that no matter at the first half of welding or and the last half welding or at the cooling time apply the load have little effect to improve the stress. Only under the entire welding process that the distribution of residual stress can be greatly improved. The results show that the residual stresses of the welding workpiece under specific pressure throughout the welding process decreased by 16.2% when compared with weld group without load applied. The maximum residual stresses of weld group without load applied are more than with the specific pressure load plates 120 MPa. But under other times putting the load cannot be improved. This paper just presents a simulation results that have a certain guiding significance