Analysis of the change in structural parameters of mechanically alloyed Cu composite materials using different milling methods

In this study, the Cu-Zr-B ternary system was investigated as it has proven to be a promising composite material used in various industries, including aerospace, automotive, electronics, nuclear and tooling, among others. Owing to its versatility and a combination of desirable properties such as high strength and hardness, corrosion and wear resistance, and thermal stability, making it suitable for a wide range of applications. The effects of mechanical alloying (MA) parameters on the Cu-Zr-B properties, including ball-to-powder ratio, rotation speed, milling time, and milling atmosphere, were examined using the X-ray analysis, scanning electron microscopy, stereological analysis, and the Williamson-Hall analysis. Different mills, namely Atritor Mill and Turbula Shaker, were used in order to determine the effect that the type of mill has on the final structural parameters of the Cu-Zr-B. All results are given after 20 hours of mechanical alloying of the composite material. The rotation speed was around 300 rpm for both devices, and the ball-to-powder ratio was 10:1 for all the cases. It was shown that the ball size also plays a significant role in the final microstructural and morphological properties of the MA powders of the Cu-Zr-B. A comprehensive analysis showed that the powders produced in the Atritor mill (Powder 1, with a uniform ball size), as well as the powders produced in the Turbula where there was a range of different ball sizes used (Powder 2), showed lower values of dislocation density and crystalline size values compared to the powders produced in the Turbula with a uniform ball size (Powder 3). It is important to state that, with time, due to the plastic deformation mechanisms present, crystallite size decreases in all cases, with the lowest value again being powder 3.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

Application of powder metallurgy in the production of the copper-based material

Copper-based materials are integral to various industries due to their remarkable properties, including electrical conductivity, strength and thermal stability. These materials have proven to be indispensable in industries such as marine, aerospace and construction. In this study, a Cu 2 wt.%-Zr 0.6 wt.%-B composite material was designed using powder metallurgy techniques. In order to get a viable material, it was subjected to mechanical alloying (MA), cold pressing, and sintering. Each of these steps highly affect the properties of the final composite material. Different parameters were taken into account for the MA process, including the ball to powder ratio (1:10 and 1:15), milling time (20h, 30h) and the weight ratio of the milling balls (uniform size (6 mm) and different sizes (6 mm, 10 mm, 25 mm)). Optimal results were obtained with a pressure of 350 MPa and for the holding time of 5 min for the cold pressing process. Holding the applied pressure for a particular duration allows the particles to rearrange and adhere to each other. It was established that 5 min was an ideal time for the consolidation of the powder. For the sintering process, a few different temperatures were tested, and the best results were obtained at 1030 oC. The microstructural parameters were analyzed using X-ray diffraction. It was noted that 1:15 MA powders had lower crystallite size values compared to 1:10 MA powders. Strain values were lower for 20h of MA compared to 30 h for 1:10 MA powders, while they were the same for 1:15 MA powder. The ball-to-powder ratio was identified as an important factor in increasing the dislocation density in MA powders, where higher dislocation density values were reached for a 1:15 ratio compared to 1:10, for the same MA duration. The size of milling balls also plays a crucial role in the MA process, as uniform-sized balls provide higher dislocation density values compared to different sized balls. Therefore, the best results for dislocation density were obtained for 1:15 powders after 30h of mechanical alloying with the uniform-sized balls.25th Jubilee Annual Conference YUCOMAT 2024 & Thirteenth World Round Table Conference on Sintering XIII WRTCS 2024, Herceg Novi, Montenegro, September 2 to 6, 2024

Basalt-based glass-ceramic composites

Two series of glass-ceramic composites (basalt/mine tailings, basalt/basalt fibers) as well as one pure glass-ceramic were prepared from basalt rocks located in the SE part of Serbia (Lukovska Banja). Both composites contained 85, 90 and 95 wt.% basalt glass respectively. The basalt glass was obtained from initial melting of basalt at 1300 °C. In the present study, the crystallization process of basalt glass contained in the glass-ceramic composite, achieved by thermal treatment, was observed, and analyzed. The thermal treatment was done at 900 °C, 950 °C, 1000 °C and 1050 °C respectively, with the retention times of 1, 3, 6, 8 and 16 hours. It was found that the addition of mine tailings and basalt fibers caused a change in the density and microstructure. The study also showed that the best mechanical and structural characteristics of the examined glassceramics were attained at the temperature of 1050 °C, with the retention time of 1 hour. Additionally, structural and optical characteristics of the glass-ceramics were assessed

Synthesis and characterization of reinforced alumina composites

Alumina composite was prepared via simple route. Alumina ceramics that resembels seashells are made of aligned micron-sized monocrystalline platelets joined together by silica secondary phase. SiO2 was added to improve mechanical properties of composite. The evolution of the phase composition during thermal treatment was investigated by X-ray powder diffraction (XRPD) and thermal analyses. Effect of sintering temperature on mechanical properties, due to the increase of sintering temperature that can produce a higher strength and higher density, was also investigated. SEM observation of composite was also included. Ceramics composites such as this are good candidates for high temperature oxidation atmosphere applications, as they have excellent mechanical and other performance requirements.VII Conference of The Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023, Belgrade, Serbi

High-entropy stabilized Zr0.2Hf0.2Ce0.2Yb0.2Gd0.2O2-δ with fluorite structure

Program and book of abstracts / 2nd International Conference on Innovative Materials in Extreme Conditions i. e. (IMEC2024), 20-22 March 2024 Belgrade, Serbia

Entropy-stabilized oxides owning fluorite structure: preparation and sintering

Entropy-Stabilized Oxides are advanced ceramic materials that possess highly desirable functional properties. Through a five-component oxide formulation, these materials utilize configurational entropy to achieve phase stabilization. In this study we have successfully synthesized a novel type of high-entropy fluorite oxide, specifically Zr0.2Hf0.2Ce0.2Yb0.2Gd0.2O2-δ, through the Self Propagation Room Temperature reaction (SPRT) method. Through heat treatment experiments, it was observed that the phase composition of all samples remained a single phase after high-temperature heating. Furthermore, a thermal treatment at 1500°C resulted in a fully crystallised single-phase fluorite structure. The powders also demonstrated a lack of agglomeration, which allowed for the sintered specimen to exhibit sufficient densification with a small porosity that was uniformly distributed throughout the samples.VII Conference of The Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023, Belgrade, Serbi

Synthesis and characterization of ceria doped with mercury

Program and book of abstracts / 2nd International Conference on Innovative Materials in Extreme Conditions i. e. (IMEC2024), 20-22 March 2024 Belgrade, Serbia

The effect of mechanical alloying parameters on the copper matrix composite materials

In powder form, copper (Cu) is the most used element in alloys and composites thanks to its affordability, availability, and capacity to easily improve its properties by adding just a few other elements [1]. It is then of no surprise that Cu composite materials find their application in various industries such as medical devices, aerospace, defense, automotive parts and electronics [2]. In this instance, a hybrid ternary Cu-2wt%Zr0.6wt%B composite was designed. Mechanical alloying (MA) was used to produce adequate powders for further composite manufacturing. The MA process was conducted in two different devices, Atritor Mill and Turbula Shaker Mixer, to determine the effect that the mixing type has on the final material. The milling parameters were set as (i.) duration for 10 h, 20 h, 30 h, and 40 h, (ii.) ball-to-powder ratio was 10:1, (iii.) inert atmosphere - argon. Electron microscopy and X-ray diffraction were used to investigate the microstructural and morphological properties of the Cu-Zr-B MA powder. Obtained results indicate that MA powders produced in Atritor show lower values of structural parameters (crystallite size, lattice parameter and lattice strain) compared to one in Turbula up to 30 h of milling. It should be noted that values of structural parameters after 40 h of milling in Turbula are lower compared to those in Atritor due to the recrystallization of Cu particles. Based on XRD results, the dislocation densities (ρ) were calculated and exhibited that MA powders milled in Atritor possess lower ρ values compared to MA powders milled in Turbula, except ρ of MA powders after 40 h. Higher values of observed structural parameters of MA powders revealed that during milling in Turbula, powders have been exposed to stronger forces in ball-powder-ball and ballpowder-wall collisions

High-entropy spinel oxides: fundamentals, synthesis and characterization

High-entropy spinel oxides (HESOs) are oxides with 5 or more cations with the general formula AB2O4 and the spinel ( Fd 3m ) structure. Due to their unique structure and properties, HESOs have shown great potential in various technological applications, i.e. they can be used as catalysts, adsorbents and photocatalysts. Since the first successful synthesis in 2018, researchers have been experimenting with different precursors and synthesis methods. However, further research is still needed in order to fully understand their capabilities and exploit their properties. The aim of this research is to synthesize novel HESOs using the self-propagating room temperature (SPRT) method, which is time and cost-effective and has not been utilized so far. Our results indicate that chlorides are not good precursors, since the formation of spinel structure has not been achieved. On the other hand, the use of nitrates has successfully led to a primary spinel ( Fd 3m ) phase. Still, certain issues persist, as secondary phases are commonly formed, especially in the presence of Mg or Cu. A potential solution that could ensure the formation of a single phase is the use of quenching from high temperatures (1000 °C), instead of gradual cooling