multi-component alloys
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The presented work considers the influence of the hafnium and molybdenum to zirconium ratio of Ti20Ta20Nb20(HfMo)20-xZrx (where x = 0, 5, 10, 15, 20 at.%) high-entropy alloys in an as-cast state for potential biomedical applications. The current research continues with our previous results of hafnium's and molybdenum's influence on a similar chemical composition. In the presented study, the microstructure, selected mechanical properties, and corrosion resistance were investigated. The phase formation thermodynamical calculations were also applied to predict solid solution formation after solidification. The calculations predicted the presence of multi-phase, body-centred cubic phases, confirmed using X-ray diffraction and scanning electron microscopy. The chemical composition analysis showed the segregation of alloying elements. Microhardness measurements revealed a decrease in microhardness with increased zirconium content in the studied alloys. The corrosion resistance was determined in Ringer's solution to be higher than that of commercially applied biomaterials. The comparison of the obtained results with previously reported data is also presented and discussed in the presented study.
- Klíčová slova
- corrosion resistance, high-entropy alloys, mechanical properties, microstructure, multi-component alloys,
- Publikační typ
- časopisecké články MeSH
A redox-complexometric determination of iron and cobalt is based on potentiometric titration of iron with EDTA, followed by that of cobalt with iron(III) chloride after addition of 1,10-phenanthroline. This method simplifies the complexometric analysis of more complicated materials.
- Publikační typ
- časopisecké články MeSH
The presented work aimed to investigate the influence of the hafnium/(zirconium and molybdenum) ratio on the microstructure, microhardness and corrosion resistance of Ti20Ta20Nb20(ZrMo)20-xHfx (where x = 0, 5, 10, 15 and 20 at.%) high entropy alloys in an as-cast state produced from elemental powder and obtained via the vacuum arc melting technique. All studied alloys contained only biocompatible elements and were chosen based on the thermodynamical calculations of phase formation predictions after solidification. Thermodynamical calculations predicted the presence of multi-phase, body-centered cubic phases, which were confirmed using X-ray diffraction and scanning electron microscopy. Segregation of alloying elements was recorded using elemental distribution maps. A decrease in microhardness with an increase in hafnium content in the studied alloys was revealed (512-482 HV1). The electrochemical measurements showed that the studied alloys exhibited a high corrosion resistance in a simulated body fluid environment (breakdown potential 4.60-5.50 V vs. SCE).
- Klíčová slova
- corrosion resistance, high entropy alloys, mechanical properties, microstructure, multi-component alloys,
- Publikační typ
- časopisecké články MeSH
The presented work was focused on investigating the influence of the (hafnium and zirconium)/molybdenum ratio on the microstructure and properties of Ti20Ta20Nb20(ZrHf)20-xMox (where: x = 0, 5, 10, 15, 20 at.%) high entropy alloys in an as-cast state. The designed chemical composition was chosen due to possible future biomedical applications. Materials were obtained from elemental powders by vacuum arc melting technique. Phase analysis revealed the presence of dual body-centered cubic phases. X-ray diffraction showed the decrease of lattice parameters of both phases with increasing molybdenum concentration up to 10% of molybdenum and further increase of lattice parameters. The presence of two-phase matrix microstructure and hafnium and zirconium precipitates was proved by scanning and transmission electron microscopy observation. Mechanical property measurements revealed decreased micro- and nanohardness and reduced Young's modulus up to 10% of Mo content, and further increased up to 20% of molybdenum addition. Additionally, corrosion resistance measurements in Ringers' solution confirmed the high biomedical ability of studied alloys due to the presence of stable oxide layers.
- Klíčová slova
- corrosion resistance, high entropy alloys, mechanical properties, microstructure analysis, multi-component alloys,
- Publikační typ
- časopisecké články MeSH
Aluminum is a widely popular material due to its low cost, low weight, good formability and capability to be machined easily. When a non-metal such as ceramic is added to aluminum alloy, it forms a composite. Metal Matrix Composites (MMCs) are emerging as alternatives to conventional metals due to their ability to withstand heavy load, excellent resistance to corrosion and wear, and comparatively high hardness and toughness. Aluminum Matrix Composites (AMCs), the most popular category in MMCs, have innumerable applications in various fields such as scientific research, structural, automobile, marine, aerospace, domestic and construction. Their attractive properties such as high strength-to-weight ratio, high hardness, high impact strength and superior tribological behavior enable them to be used in automobile components, aviation structures and parts of ships. Thus, in this research work an attempt has been made to fabricate Aluminum Alloys and Aluminum Matrix Composites (AMCs) using the popular synthesis technique called stir casting and join them by friction stir welding (FSW). Dissimilar grades of aluminum alloy, i.e., Al 6061 and Al 1100, are used for the experimental work. Alumina and Silicon Carbide are used as reinforcement with the aluminum matrix. Mechanical and corrosion properties are experimentally evaluated. The FSW process is analyzed by experimentally comparing the welded alloys and welded composites. Finally, the best suitable FSW combination is selected with the help of a Multi-Attribute Decision Making (MADM)-based numerical optimization technique called Weighted Aggregated Sum Product Assessment (WASPAS).
- Klíčová slova
- alloys, aluminum, composites, friction stir welding, multi-attribute decision making, optimization, parameters, properties, stir casting,
- Publikační typ
- časopisecké články MeSH
The method of making parts through additive manufacturing (AM) is becoming more and more widespread due to the possibility of the direct manufacturing of components with complex geometries. However, the technology's capacity is limited by the appearance of micro-cracks/discontinuities during the layer-by-layer thermal process. The ultrasonic (US) method is often applied to detect and estimate the location and size of discontinuities in the metallic parts obtained by AM as well as to identify local deterioration in structures. The Ti6Al4V (Ti64) alloy prepared by AM needed to acquire a high-quality densification if remarkable mechanical properties were to be pursued. Ultrasonic instruments employ a different type of scanning for the studied samples, resulting in extremely detailed images comparable to X-rays. Automated non-destructive testing with special algorithms is widely used in the industry today. In general, this means that there is a trend towards automation and data sharing in various technological and production sectors, including the use of intelligent systems at the initial stage of production that can exclude defective construction materials, prevent the spread of defective products, and identify the causes of certain instances of damage. Placing the non-destructive testing on a completely new basis will create the possibility for a broader analysis of the primary data and thus will contribute to the improvement of both inspection reliability and consistency of the results. The paper aims to present the C-scan method, using ultrasonic images in amplitude or time-of-flight to emphasize discontinuities of Ti64 samples realized by laser powder-bed fusion (L-PBF) technology. The analysis of US maps offers the possibility of information correlation, mainly as to flaws in certain areas, as well as distribution of a specific flaw in the volume of the sample (flaws and pores). Final users can import C-scan results as ASCII files for further processing and comparison with other methods of analysis (e.g., non-linear elastic wave spectroscopy (NEWS), multi-frequency eddy current, and computer tomography), leading to specific results. The precision of the flight time measurement ensures the possibility of estimating the types of discontinuities, including volumetric ones, offering immediate results of the inspection. In situ monitoring allows the detection, characterization, and prediction of defects, which is suitable for robotics. Detailing the level of discontinuities at a certain location is extremely valuable for making maintenance and management decisions.
- Klíčová slova
- additive manufacturing, microstructure, titanium alloy, ultrasound testing,
- Publikační typ
- časopisecké články MeSH
Machining with rotating tools appears to be an efficient method that employs a non-standard kinematic turning scheme. It is used in the machining of materials that we classify in the category of difficult to machine. The titanium alloy Ti-6Al-4V, which is widely used in industry and transportation, is an example of such material. Rotary tool machining of titanium alloys has not been the subject of many studies. Additionally, if researchers were dissatisfied with their findings, the reason may not be the kinematic machining scheme itself but rather the tool design and the choice of cutting parameters. When tools are constructed of several components, inaccuracies in production and assembly can arise, resulting in deviations in the cutting part area. A monolithic driven rotary tool eliminates these factors. In the machining process, however, it may react differently from multi-component tools. The presented work focuses on the research of the technology for machining titanium alloy Ti-6Al-4V using a monolithic driven rotary tool. The primary goal is to gather data on the impact of cutting parameters on the machining process. The cutting force and the consequent integrity of the workpiece surface are used to monitor the process. The speed of workpiece rotation has the greatest impact on the process; as it increases, the cutting force increases, as do the values of the surface roughness. In the experiment, lower surface roughness values were attained by increasing the feed parameter and the depth of cut. This may predetermine the inclusion of a kinematic scheme in highly productive technologies.
- Klíčová slova
- actively driven tool, rotary tool, titanium alloy, turning,
- Publikační typ
- časopisecké články MeSH
This article aims to review a redesign approach of a student racing car's clutch lever component, which was topologically optimized and manufactured by Additive Manufacturing (AM). Finite Element Method (FEM) analysis was conducted before and after a Topology Optimization (TO) process in order to achieve equivalent stiffness and the desired safety factor for the optimized part. The redesigned clutch lever was manufactured by using AM-Selective Laser Melting (SLM) and printed from powdered aluminum alloy AlSi10Mg. The final evaluation of the study deals with the experimental test and comparison of the redesigned clutch lever with the existing part which was used in the previous racing car. Using TO as a main redesign tool and AM brought significant changes to the optimized part, especially the following: reduced mass of the component (10%), increased stiffness, kept safety factor above the 3.0 value and ensured the more aesthetic design and a good surface quality. Moreover, using TO and AM gave the opportunity to consolidate multi-part assembly into a single component manufactured by one manufacturing process that reduced the production time. The experimental results justified the simulation results and proved that even though the applied load was almost 1.5× higher than the assumed one, the maximum von Mises stress on the component was still below the yield limit of 220 MPa.
- Klíčová slova
- 3D printing, AlSi10Mg, FEM, SLM, additive manufacturing, finite element method, selective laser melting, topology optimization,
- Publikační typ
- časopisecké články MeSH
Silicon-germanium multilayer structures consisting of alternating Si and Ge amorphous nanolayers were annealed by ultrashort laser pulses at near-infrared (1030 nm) and mid-infrared (1500 nm) wavelengths. In this paper, we investigate the effects of the type of substrate (Si or glass), and the number of laser pulses (single-shot and multi-shot regimes) on the crystallization of the layers. Based on structural Raman spectroscopy analysis, several annealing regimes were revealed depending on laser fluence, including partial or complete crystallization of the components and formation of solid Si-Ge alloys. Conditions for selective crystallization of germanium when Si remains amorphous and there is no intermixing between the Si and Ge layers were found. Femtosecond mid-IR laser annealing appeared to be particularly favorable for such selective crystallization. Similar crystallization regimes were observed for both single-shot and multi-shot conditions, although at lower fluences and with a lower selectivity in the latter case. A theoretical analysis was carried out based on the laser energy absorption mechanisms, thermal stresses, and non-thermal effects.
