The evolution of the microstructure during plastic deformation was studied in an additively manufactured Ti-15%Nb-12%Zr (at.%) alloy. The applied equivalent strain ranged extremely widely from 8 % to 20,800 %. Strains below 100 % were achieved by uniaxial compression, while the high strains were obtained by the highpressure torsion (HPT) technique. In addition to the as-built material, the same investigation was conducted on the alloy after heat treatment at 550 degrees C for 1 h after additive manufacturing. The as-built alloy had a fully body-centered cubic structure, while the annealing step resulted in the development of a hexagonal close-packed secondary alpha-Ti phase with a fraction of about 10 %. Compression up to a strain of 70 % resulted in an increase in the secondary phase fraction to 12 % and 22 % for the as-built and heat-treated alloys, respectively. HPT processing at high strains yielded a lower secondary phase fraction due to reverse martensitic transformation. The dislocation density increased to 70-100 x 1014 m(-2) when the strain rose to 70 % during compression. The dislocation density reached extremely large values of 600-700 x 1014 m(-2) at a strain of about 20,800 % achieved by HPT. Although the dislocation density increased by two orders of magnitude and nano-crystallization also occurred when the strain increased to 20,800 %, the hardness was enhanced only by 10-30 %. The unexpectedly low hardness increase after HPT was attributed to unique deformation mechanisms such as the kink pair related dislocation motion and grain boundary sliding.

High-entropy alloys (HEAs) represent one of the most promising emerging material families, particularly for advanced surface engineering applications. In this work, a near-high-entropy alloy (near-HEA) coating was produced on a 316L stainless steel substrate using laser metal deposition (LMD) from a powder mixture of Inconel 625, Cr and Mo, without the intentional addition of Fe. Due to dilution from the substrate, the resulting alloy contained elevated Fe content while maintaining Cr, Ni and Mo concentrations within the generally accepted compositional range of HEAs. The deposited layer exhibited a dual-phase microstructure consisting of a face-centered cubic (FCC) phase and a highly distorted tetragonal phase forming a periodic network with a characteristic length scale of several hundred nanometers. The hardness of the coating increased to approximately three times that of the substrate, reaching values of 600-700 HV. To further modify the surface properties, laser-induced periodic surface structures (LIPSS) were generated on the polished coating using femtosecond pulsed laser irradiation at different energy densities. The morphology and subsurface structure of the resulting periodic patterns were investigated by scanning electron microscopy. LIPSS with characteristic dimensions ranging from the micrometer to nanometer scale were successfully produced. Cross-sectional analyses revealed that the underlying dual-phase microstructure remained continuous within the laser-structured regions, indicating that LIPSS formation occurred predominantly via metallic ablation without significant phase transformation or amorphization. These results demonstrate the combined applicability of LMD and femtosecond laser structuring for producing mechanically enhanced, micro- and nanostructured near-HEA coatings with potential for advanced surface-related functionalities.

This study explores the fabrication of an equimolar CoCrFeNi high-entropy alloy (HEA) using laser metal deposition (LMD) technique on a 316 L austenitic stainless steel substrate, without pre-alloying. Elemental metal powders were mixed in a planetary ball mill and directly deposited to investigate the effect of layer number on alloy composition and substrate intermixing. Experimental results revealed significant dilution in the first four layers, with substrate intermixing affecting composition. The coarse-grained crystal structure observed in the initial layers persisted in subsequent layers, and hardness measurements indicated the cumulative thermal effects of sequential deposition. From an industrial perspective, this approach offers a cost-effective and flexible manufacturing strategy, eliminating the need for pre-alloying. Moreover, gradient compositional layers can be achieved, enabling tailored material properties. This work demonstrates the feasibility of producing multi-layer HEAs directly from elemental powders while addressing the challenges of compositional stability.

We have developed a convenient route to transform biomass power plant ashes (BPPA) into porous sponge-like fertilizer composites. The absence of water prevents the chemical reaction and carbon dioxide formation when concentrated sulfuric acid is mixed with BPPA and CaCO3. Adding water, however, initiates the protonation reaction of carbonate ion content and starts CO2 evolution. The key element of the method was that the BPPA and, optionally, CaCO3 and/or CaSO4·0.5H2O were mixed with concentrated sulfuric acid to make a paste-like consistency. No gas evolution occurred at this stage; however, with the subsequent and controlled addition of water, CO2 gas evolved and was released through the channels developed in the pastry-like material due to the internal gas pressure, but without foaming. Using a screw-containing tube reactor, the water can be introduced under pressure. Due to the pressure, the pores in the pastry-like material became smaller, and consequently, the mechanical strength of the granulated and solidified mixture became higher than that of the reaction products prepared under atmospheric pressure. The main reaction products were syngenite (K2Ca(SO4)2·H2O) and polyhalite (K2Ca2Mg(SO4)4·2H2O). These compounds are valuable fertilizer components in themselves, but the material’s porous nature helps absorb solutions of microelement fertilizers. Surprisingly, concentrated ammonium nitrate solutions transform the syngenite content of the porous fertilizer into ammonium calcium sulfate ((NH4)2Ca(SO4)2·2H2O, koktaite). Koktaite is slightly soluble in water, thus the amount of ammonium ion released on the dissolution of koktaite depends on the amount of available water. Accordingly, ammonium ion release for plants can be increased with rain or irrigation, and koktaite is undissolved and does not decompose in drought situations. The pores (holes) of this sponge-like fertilizer product can be filled with different solutions containing other fertilizer components (phosphates, zinc, etc.) to adjust the composition of the requested fertilizer compositions for particular soils and plant production. The method allows the preparation of ammonium nitrate composite fertilizers containing metallic microelements, and various solid sponge-like composite materials with adjusted amounts of slowly releasing fertilizer components like syngenite and koktaite.

Optimization of 3D printing parameters was studied for the difficult to print, brittle Fe-6.5 wt%Si, applying powder bed fusion (PBF) technology. Printing orientation, volumetric energy density (VED), built plate (BP) temperature, as deposition parameters and the influence of post-deposition heat treatment (HT), were investigated. The optimal parameters were established based on the EBSD figures of samples deposited in different orientations, optical microscopy images, CT measurements, DC hysteresis curves, complex permeability spectra, and XRD patterns.

Experiments were conducted to reveal the refinement of the microstructure and the evolution of the hardness of an additively manufactured (AM) CoCrFeNi multi-principal element alloy (MPEA) processed by severe plastic deformation (SPD) using high pressure torsion (HPT) technique. AM was carried out by laser powder bed fusion (L-PBF) technique at two different laser scan speeds. The as-built alloys for both laser scan speeds have a single-phase face-centered cubic (fcc) structure with <110> fiber texture parallel to the building direction. X-ray line profile analysis (XLPA) revealed that the dislocation density was considerably high even in the AM-processed state before HPT (3 × 1014 m−2) which increased by two orders of magnitude during HPT. The saturation of the lattice defects (dislocation density and twin fault probability) as well as the crystallite size occurred at a shear strain of about 10 during HPT. In both AM-processed alloys, <111> fiber texture developed parallel to the normal of the HPT-processed disks. For both laser scan speeds, the initial grain size in the AM-processed samples was refined from 70 to 90 μm to the nanocrystalline regime after 10 turns of HPT. Additionally, nanotwins formed with a probability of about 3 %. The initial hardness of the AM-processed MPEA samples for both laser scan speeds was 2700–2800 MPa, which is superior to that of CoCrFeNi produced by casting (about 1380 MPa). This can be explained by the high dislocation density in the AM-processed specimens. The formation of nanostructure with high lattice defect density during HPT resulted in a very high hardness value of about 5500 MPa in the AM-processed CoCrFeNi MPEA samples for both laser scan speeds.

The increase in the risks of mosquito-transmitted serious diseases or viral infections generates strong motivations to find new and efficient solutions for controlling blood-sucking mosquitoes. There are selective protein toxins such as BTI (Bacillus thüringiensis israelensis) used to kill mosquito larvae, which require carrier materials that keep the active ingredient on the surface of the water where the mosquito larvae feed. Environmentally friendly and effective composite carrier materials consisting of gypsum and perlite with controlled floating and sinking times were developed. The partial closing of open pores with modified cellulose derivatives as carboxymethyl cellulose (CMC) or cricket made from corn starch and hot water were used to ensure the slow dissolution of “CMC corks” in the pores, which can control the floating and sinking properties as well. The carrier composites were combined with BTI toxins such as 4% Vectobac WP (5000 ITU (international toxic unit)) toxin, resulting in a 90–100% killing rate against different tests (Culex pipiens) and various naturally abundant mosquito larva species. The stability test of the BTI-containing new carrier materials shows good applicability at flooded/dried/re-flooded areas where the flooding is temporary thus the composites can be applied as preventive treatment as well.

Regular wave patterns were created by a 2 kV gallium ion on Si(111) monocrystals at incidence angles between 60° and 80° with respect to the surface normal. The characteristic wavelength and surface roughness of the structured surfaces were determined to be between 35–75 nm and 0.5–2.5 nm. The local slope distribution of the created periodic structures was also studied. These topography results were compared with the predictions of the Bradley–Harper model. The amorphised surface layers were investigated by a spectroscopic ellipsometer. According to the results, the amorphised thicknesses were changed in the range of 8 nm to 4 nm as a function of ion incidence angles. The reflectance of the structured surfaces was simulated using ellipsometric results and measured with a reflectometer. Based on the spectra, a controlled modification of reflectance within 45% and 50% can be achieved on Si(111) at 460 nm wavelength. According to the measured results, the characteristic sizes (periodicity and amplitude) and optical property of silicon can be fine-tuned by low-energy focused ion irradiation at the given interval of incidence angles.

Amorphous electroless Ni-B coatings were deposited on steel substrates with different surface morphologies and B contents (6.5–8.64 wt.%) that could be changed by altering the temperature and the composition of the baths. The supercapacitive behavior of the coatings was evaluated by cyclic voltammetry and galvanostatic charge–discharge measurements, and it was found that Ni-B coatings had higher capacitance than pure electroless Ni or the bulk Ni plate. A close relationship was identified between the microstructure, the B content, and the capacitive behavior of the coatings. The presence of the B alloying element had the most significant effect in determining the capacitance, while the surface area and particle size also contributed to its increase. A surface-specific capacity of 31 mF/cm2 was achieved by the coating containing the highest B content and largest AFM surface area. Furthermore, it was revealed that the particle size of the deposits was determined by the combined effect of the bath temperature and the B content under the applied experimental conditions. The obtained results indicate that Ni-B coatings are promising candidates for supercapacitive applications.

The A356 alloy is commonly used in the foundry industry to produce high-stressed automotive components, such as motor frames and cylinder heads. The aim of this work was to investigate how the mechanical and tribological properties of this alloy can be improved by applying an anodizing process. The properties of the oxide layer formed by anodizing using oxalic acid at low temperatures were characterized by different analytical and tribological methods. The combination of tribological methods with standard measurement techniques—such as hardness measurement, layer thickness measurement, as well as the analysis of the morphological characteristics—was used to track the layer evolution during wear developments.

316L stainless steel was manufactured by additive manufacturing (AM), and then, the samples were severely deformed by the high-pressure torsion (HPT) technique. The evolution of the microstructure was monitored by X-ray line profile analysis. This method gives the crystallite size and the density of lattice defects, such as dislocations and twin faults. The AM-processing of the HPT disks was performed in two different modes: the laser beam was parallel or orthogonal to the normal direction of the disks. The subsequent HPT deformation was carried out for ½, 1, 5 and 10 turns. The microstructure and hardness evolution during HPT were similar regardless of the laser beam direction. For both sample series, the minimum achievable crystallite size was about 30 nm, while the dislocation density and the twin fault probability got saturated at the values of 300–350 × 10 14 m −2 and 3.5–4%, respectively. The microstructure evolution during HPT of the AM-prepared 316L steel was compared with the HPT-induced changes in an as-cast counterpart. It was found that while the AM-prepared 316L steel remained a single-phase face-centered cubic γ-structure during HPT, in the as-cast samples a body-centered cubic (bcc) martensitic α-phase became the main phase with increasing the imposed strain of HPT due to the lower Ni content. In the saturation state achieved by HPT the initially as-cast 316L steel had a considerably higher hardness (about 6000 MPa) than that for the AM-prepared samples (~ 5000 MPa) due to the large fraction of the hard bcc phase formed during HPT.

A lézeres kezelés által létrehozott periodikus felületi struktúrákat röviden LIPSS-eknek (laser-induced periodic surface structures) nevezzük. A lézeres felületkezelés során végbemenő fizikai folyamatok szabályozásával a kialakított felületek morfológiai és fizikai tulajdonságai beállíthatók, ennek megfelelően azok számos felhasználási lehetőséggel bírnak. A LIPSS egyik alkalmazásorientált felhasználása a felületerősített Raman-spektroszkópiában (SERS) alkalmazott SERS-hordozók, melyek segítségével molekulák extrém kis koncentrációja is kimutatható. A kísérleti munka során femtoszekundumos lézerberendezés segítségével SERS-hordozót készítettünk, melynek SERS-erősítését vizsgáltuk.

Abstract This paper investigates the phenomenon of Laser-induced Periodic Surface Structures (LIPSS) on Si single crystals. As usual, by variation of parameters, the morphological and physical properties of the resulting surfaces can be tailored, with respect to their use in many applications. One application-oriented use of LIPSS is the preparation of SERS (Surface Enhanced Raman Spectroscopy) substrates, which can be used to detect extremely low concentrations of molecules. In this experimental work, a possible way of manufacturing of SERS substrates, followed by SERS enhancement testing has been shown.

A mérnöki tervezés célja szénszálerősítésű műanyag alkatrész vízzárásának kialakítása volt. Alapanyagként 50 μm vastag ausztenites rozsdamenetes acélfóliát használtunk. A borítás kialakításához, a megadott alkatrész geometriájához illeszkedő, mélyhúzott elemeket hegesztettünk össze. A mélyhúzó szerszámok és a hegesztőkészülék saját tervezésű és gyártmányú volt. A terítékek vágását, majd a mélyhúzott terítékek hegesztési technológiáját Trumpf gyártmányú TruMark 5010 típusú jelölő lézerrel valósítottuk meg.

The reduction of undesirable chlorate (ClO3-) is important from both an environmental and an industrial point of view. In our work, cellulose-based catalysts have been designed for chlorate reduction by using palladium, platinum, and iron oxide. The produced catalysts were characterized by SEM, TEM, XRD, FTIR, and ICP. Even though low precious metal content (<0.6 wt%) was used during the catalyst preparation, high catalytic activity was achieved, and the conversion was as high as 92.5%. Furthermore, a continuous chlorate hydrogenation and monitoring system has also been developed within which the reduction has been carried out successfully and after about 160 min the ClO3- content has been reduced to zero.

The present investigation is directed to phase transitions in the equimolar NiCoFeCrGa high entropy alloy, which is a mixture of face-centered cubic (FCC) and body-centered cubic (BCC) crystalline phases. The microstructure of the samples was investigated by using scanning electron microscopy (SEM), time-of-flight secondary ion mass spectroscopy (TOF-SIMS), transmission electron microscopy-based energy-dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS), as well as X-ray diffraction (XRD) measurements. Based on the phases observed in different temperature ranges, a sequence of the phase transitions can be established, showing that in a realistic process, when freely cooling the sample with the furnace from high to room temperature, a microstructure having spinodal-like decomposition can also be expected. The elemental mapping and magnetic behaviors of this decomposed structure are also studied.

Abstract The purpose of this engineering design was to fabricate a waterproof coat for a carbon fibre reinforced polymer component. Austenitic stainless steel foil with 50μm thickness was used as the raw material. Deep-drawn elements that fit the geometry of the given part were welded together to form the coat. The deep drawing tools and the welding machine were self-designed and manufactured. The cutting of the blank and then the welding technology of the deep-drawn tablecloths were carried out with a TruMark 5010 marking laser made by Trumpf

Experiments were performed with femtosecond laser on monocrystalline silicon for different application fields.The small focal spot diameter, the ultra-short pulse length, and the high energy density opens new ways in material processing; the treated material will have smaller heat affected zone (HAZ), and allow more precise, higher quality material processing.Micropillars and LIPSS structures were prepared on monocrystalline silicon in our study.

Abstract Experiments were performed with femtosecond laser on monocrystalline silicon for different application fields. The small focal spot diameter, the ultra-short pulse length, and the high energy density opens new ways in material processing; the treated material will have smaller heat affected zone (HAZ), and allow more precise, higher quality material processing. Micropillars and LIPSS structures were prepared on monocrystalline silicon in our study.