Papers by Keyword: Metals

Abstract: Predicting the microstructural state during manufacturing is critical, as it directly governs the material's final mechanical properties. Accurate prediction of microstructure evolution in multi-stage industrial hot deformation processes, such as rolling, is limited by the lack of experimental data at intermediate stages, where direct measurement is impractical. To address this, an integrated methodology combining finite element (FE) simulation in QForm UK® software, physical simulation using the Thermo-Mechanical Treatment Simulator (TMTS), and artificial intelligence (AI) is proposed and investigated. The methodology is demonstrated for the 11-pass hot rolling of a 41Cr4 steel bar. Thermomechanical loading histories from an FE model of the industrial process were used to design and simulate a targeted TMTS experiment, generating a synthetic dataset via an analytical JMAK model that combines multiple recrystallisation mechanisms. This data was used to train a recurrent neural network (RNN) with an augmented physics-informed Long Short-Term Memory (LSTM) cell to predict the totally recrystallised fraction (RX) solely from loading history data. The AI model achieved high accuracy when validated within the TMTS simulation domain, successfully capturing different recrystallisation regimes. Implementation within commercial FE software enabled direct prediction in the rolling process simulation, yielding promising predictive capability, particularly in regions with thermal histories similar to the training data, highlighting the critical importance of training data diversity. This work establishes a proof of concept for a novel calibration methodology, where targeted physical simulation bridges the gap between industrial process complexity and data-driven AI model development, offering a practical solution for modelling scenarios where traditional experimental calibration is infeasible.

Abstract: Irradiation of materials in space or nuclear applications is unavoidable and it is well known that it modifies their properties (electronic, optical, thermal, mechanical, ..) due to the formation of point and complex defects (vacancies Vs, self-interstitial atoms SIAs, cavities, bubbles, dislocation loops, dislocation lines, precipitates). As this review shows, irradiation can also be very useful for intentionally optimizing material properties and, when performed under very well controlled conditions, for understanding defects properties and their impact on large-scale material properties. Knowledge of how damage is created and accumulated in materials is needed to better understand the behavior of materials under irradiation, in particular their radiation resistance for nuclear applications or to know the best irradiation conditions for optimizing their properties in electronic or optical applications. Experimental characterization of damage is an essential element in achieving this objective, and is very often coupled with simulation. This paper presents general information on the introduction of damage during irradiation of materials and various examples illustrating the typical advantages of the Positron Annihilation Spectroscopy (PAS) technique for the study of radiation damage.

Abstract: This study evaluates the effect of the vibration assisted ball burnishing method on surface integrity of maraging C300 steel surfaces printed by additive manufacturing with Selective Laser Melting (SLM) technology. The analysis contemplates variations in tool preloads and applied force. The analyzed C300 material is based on the as-built (AM), machined (M) and vibration assisted ball burnishing (VABB) states. Surface roughness was evaluated to assess topographical conditions both before and after the burnishing process. Microstructure and mechanical deformation were analyzed by Scanning Electron Microscopy (SEM) technique to examine the stresses generated by compression effect. It was found that forces in the range of 180 to 220 N reduce the roughness Sa value by up to 59% with respect to the M finish and up to 97% with respect to the AM finish. Furthermore, burnishing parameters significantly vary the final quality of the surfaces depending on the initial state of the surface and the conditions of the material.

Abstract: The joining of metals and polymer-based materials has a very high interest for many industrial sectors, as it allows to achieve components combining the specific characteristics of each material class. Additive manufacturing technologies could boost the production of these joints, allowing the controlled deposition of a polymeric material over the metal substrate. The present research is aimed to study the feasibility of a joint concept that can be used to produce aluminium/polymer-based material joints through a 3D printing-supported technique. The innovative joint concept, which is based on an interlocking mechanism promoted by a deposited pin, was compared to two conventional concepts. The innovative joint concept allows the production of samples with good mechanical behaviour, in which the failure occurs outside the material overlapping zone. This design is very suitable to be tested for the production of dissimilar material joints.

Abstract: The paper deals with research on a hybrid technique of coating by Electrical Discharge Deposition (EDD) which has the advantage of lower costs than the other similar methods. This is due to the possibility of using a usual electrical discharge machine, with common tooling, aided by electromagnetic coils that increase the precision and the quality of deposed layers. Some metallic materials like W, Al, Ni, and Ti of high purity are used for EDD, which could be taken from available wires providers. Numerical simulation of the EDD process, using the metals mentioned above was achieved in Comsol Multiphysics. Two connected modules (physics) were used: Magnetic Fields that produced the magnetic force that actuated each of these four categories of ions and Charged Particle Tracing that highlighted the distribution of particles on different cut planes – Poincare maps. Based on these results provided by numerical simulation, it was possible to evaluate the ions behavior, in comparison to electrons, during EDD that is influenced by their atomic mass and the charge number.

Abstract: Drug resistant microbial strains are becoming continuous dilemma for researchers; hence, some alternates are required to combat this issue. In this way, nanotechnology is fascinating researchers to put forward a step in order to synthesize metals nanoparticles via adopting an ecofriendly, facile, and quick approach using medicinal plants. By means of aqueous extract of Polyalthia longifolia (AEPl), gold nanoparticles (AuPl) were synthesized for the mechanism study of synthesis and antibacterial bahavior. The reddish colored solution was an indicative clue of synthesis showing surface plasmon band at 540nm using UV/Visble spectroscopy. Various functional groups in the extract were identified which participated in the reduction of metal ions to metallic form as indicated from the Fourier Transform Infrared (FTIR) spectra of AuPl. Moving ahead, the synthesized AuPl were characterized through Transmission Electron Microscopy (TEM) showed spherical shape with more or less 50nm size. Besides, Scanning Electron Microscopy (SEM) study revealed some aggregates formation. Further, structural characterization via X-Rays Diffractometry (XRD) displayed crystallline nature of these nanoparticles. Finally, Energy Dispersive X-rays (EDX) analysis described their metallic form. The antibacterial activity at increased concentration when measured; AuPl showed 15 and 18mm bacterial growth inhibition zones against Escherichia coli and Bacillus subtilis at 100μg/mL concentration respectively. In addition, significant least minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of AuPl against these microbes were also observed. In the light of the above knowledge, it is inferred that the biogenic AuPl exhibit strong antibacterial potential enabling them to be a good substitute of antibiotics.

Abstract: This study deals with the synthesis of cubic shape platinum nanoparticles (Pt NPs) by adjusting the oleylamine (OAm):polyvinylpyrrolidone (PVP) ratio in the solution media. The mass ratios between the OAm:PVP were respectively set to the 1:2, 1:1, 2:1 values. Platinum acetylacetonate (Pt(acac)₂) was used as Pt precursor and the reduction of this salt to the metallic Pt was provided by microwave irradiation technique. It is seen that increasing amount of OAm triggers the formation of cubic shape Pt NPs. The average sizes of the Pt NPs fall in the range of 6-8 nm. The unsupported Pt NPs were directly used as a catalyst for the oxygen reduction reaction (ORR). According to the hydrodynamic ORR voltammograms of the catalysts, the Pt NPs prepared with 1:2 (OAm:PVP) exhibit the highest current density at all stirring rates of rotating disc electrode (RDE). Besides, Pt NPs prepared with 2:1 (OAm:PVP) have the minimum charge transfer resistance based on electrochemical impedance spectroscopy (EIS) analysis conducted at 0.9 V. After all these analyses, Pt NPs were synthesized using extra five different ratios (1.5:1, 1:1.5, 2.5:1, 3:1, 1:3) of (OAm:PVP) for thoroughly examining the optimum value for the ORR catalytic activity. As a result, the Pt NPs prepared with a 2.5:1 (OAm:PVP) ratio provided the best performance among all the catalysts.

Abstract: This paper presents the results of the application of new unique techniques based on plasma nanotechnology in metallurgy and materials science. In recent years, a team of authors have developed the solutions for extraordinary problems arising in the conditions of metallurgical enterprises related to the production of synthetic materials and control of manufactured products, namely, the methods for the production of various structural materials and optimization of methods for their non-destructive testing by atomic emission spectral analysis (AESA). The paper points out some aspects of ongoing research, in particular, an innovative technique that allows obtaining ultrapure samples of white corundum by plasma melting of alumina in a reactor. This method also allows obtaining ultrapure aluminum at the output, which can be used for the purposes of hydrogen energy. In the course of the research, the criteria for thermal protection, temperature conditions and optimal parameters of the plasmatron were determined. In order to carry out the studies of metals and alloys by AESA method, a new global analytical method was developed, which made it possible to take into account the influence of various important parameters, including third elements, background plasma radiation, etc. This method has been preliminary tested on emission spectrometers made in Russia and can significantly reduce the error in the determination of low concentrations of elements. In addition to the consideration of these parameters, the method makes it possible to perform high-precision calibration of atomic emission spectrometers of the same type (produced in series), using not a set of several tens of approved standard samples, but only two standard samples. For each area, patent applications were formed and filed.

Abstract: The oxidation processes for compact and powdery samples of titanium, copper, and molybdenum with different volume structure and dispersivity were studied using thermal analysis, electron microscopy, and X-ray diffraction. It is established that producing of metals with a modified structure under conditions of high-energy impact (severe plastic deformation, electric explosion of a thin wire) in accordance with intermediate annealing leads to an increase in the content of oxygen in the form of solid solutions and oxides; the oxide component’s share, form and localization within the material depend on physicochemical properties of both metal and oxide . It is shown that the structural-phase transformations of the oxide component during heating of fine-grained metals and powders have a significant effect on the parameters of the oxidation process of such materials. The thermally induced effects in the oxygen-containing components might play a critical role for the structure stability during long-term use of such materials under cyclic thermomechanical impacts.

Abstract: In the present work, in the framework of solving the problem of obtaining a new generation of materials with a set of properties not inherent in traditional metal and non-metal types, the practical necessity of developing a unified approach to designing their structure and properties is substantiated. Within the framework of the paradigm of multi-level structural organization of materials, based on a single model of chemical bonding, a generalization of physicochemical prrinciples was carried out, revealing the unity of nature and the causes of differences in the structure and properties of metallic and non-metallic substances and materials. Through the effects of the ratio of the components of the chemical homo - or heteronuclear interaction of the elements of the fine microstructure of substances and materials on the differences in subsequent levels of the structure (molecular and non-molecular, etc.) and properties (conductor-dielectric, ductile, elastic or fragile and hard, etc.) of metals and nonmetals the practical significance of the scientific approach developed in the work was shown.