Several studies in biomedicine have demonstrated the advantages of biodegradable and biocompatible metals for temporary implants, as they naturally degrade within the body, eliminating the need for surgical removal. Among them, magnesium–aluminium–zinc alloys, such as AZ31, show potential for controlled degradation in physiological environments, but their primary limitation is their rapid degradation.[1] This accelerated corrosion compromises implant integrity, leading to premature failure and limiting clinical applications. Thus, effective protective strategies are essential to enhance their corrosion resistance.

This study aimed to (a) perform a surface pretreatment to improve adhesion between the protective coating and the AZ31 alloy, and (b) develop a PMMA–siloxane–silica coating to reduce degradation. The formulation, based on 3-(methacryloyloxy)propyl trimethoxysilane and methyl methacrylate, was optimized for enhanced protective properties[2]. Its synthesis was characterized using real-time Fourier transform infrared spectroscopy, while its surface morphology and composition were analyzed via scanning electron microscopy and energy-dispersive spectroscopy. Corrosion resistance was evaluated through immersion tests in simulated body fluid (SBF) using potentiodynamic polarization and electrochemical impedance spectroscopy. Additionally, degradation behaviour was evaluated by monitoring pH variations and hydrogen evolution in SBF over time.

The results confirm that the PMMA–siloxane–silica coating significantly enhanced AZ31 corrosion resistance, ensuring controlled degradation. These findings present the potential of siloxane–silica coatings for biomedical applications.

References:

[1] M. He, L. Chen, M. Yin, et al., Review on magnesium and magnesium-based alloys as biomaterials for bone immobilization, J. Mater. Res. Technol. 23 (2023) 4396–4419. https://doi.org/10.1016/j.jmrt.2023.02.037.

[2] P. Rodič, B. Kapun, I. Milošev, Durable Polyacrylic/Siloxane-Silica Coating for the Protection of Cast AlSi7Mg0.3 Alloy against Corrosion in Chloride Solution, Polymers 15 (2023) 3993. https://doi.org/10.3390/polym15193993.

Acknowledgements:

Financial support was provided by the Slovenian Research and Innovation Agency (ARIS) under research core funding P1-0134, P2-0393 and P2-0089 and through the ARIS project J2-60047.

This study explores the influence of various Metal Inert Gas (MIG) brazing modes on critical factors such as the process stability, bead morphology, microstructure and mechanical performance of brazed lap joints of dual-phase (DP600) steel. Through systematic analysis of voltage/current signals and deposition characteristics, this research reveals how variations in heat input impact material flow and wettability during the brazing process. A higher heat input has been found to enhance wettability and improve joint strength, yet it can lead to a reduction in the cross-sectional area, ultimately affecting resistance to failure. Conversely, lower heat inputs contribute to more stable deposition, which enhances resistance to failure and defects, but too low wettability can also cause premature failure of the joints. Additionally, this study identifies key process behaviours, including the tendency for increased instability at higher wire feed rates and the significant role of bead morphology in determining mechanical performance. By elucidating these process–property relationships, this research provides a valuable framework for selecting appropriate MIG brazing parameters tailored to specific applications. The findings significantly contribute to the development of process control strategies aimed at enhancing joint reliability, offering critical insights for industries focused on optimizing brazing techniques to achieve improved structural integrity and overall performance in their applications.

Introduction
Super duplex steel 03Cr23Ni6Mo4Cu3NbN (SDS) is a new development of JSC “NPO ‘TSNIITMASH’, which has high corrosion and strength characteristics which are in demand in the oil and gas industries, as well as in chemical industry and nuclear power engineering. The combination of these characteristics is ensured by uniform distribution of austenite and ferrite. Special attention is paid to the technology of ingots and forgings manufacturing, prevention of formation and growth of σ-phase, and other secondary phases which negatively affect the mechanical and operational properties of steel. The influence of chemical composition and technological parameters, including ingot solidification and forgings cooling rates, on structure formation is investigated using computer modeling and experimental studies.

Methods
- Modeling of phase transformations of 1000 chemical compositions is carried out using the program complex Thermo-Calc version 2022a (with PRISMA) using databases TCFE11, MOBFE6.
- Production of 03Cr23Ni6Mo4Cu3NbN steel samples takes place using electroslag remelting (ESR) with the provision of increased crystallization rates. The cooling rates from 2.5 to 42 ℃/s are realized when the forgings are quenched.
- The chemical composition, microstructure, and impact toughness of steel are determined.

Results
The influence of alloying elements and cooling rate of forgings on the kinetics of σ-phase formation is described on the basis of computer modeling. Parametric models approximating the results of thermodynamic and kinetic calculations are developed. The models allow us to calculate the fraction of σ-phase at given cooling rates to estimate the value of impact toughness of steel.

Conclusions
On the basis of regression analysis, the influence of nitrogen, molybdenum, nickel, copper and carbon on the value of critical cooling rate has been established.
The equation for calculation of impact toughness depending on the volume fraction of σ-phase has been proposed.
The possibility of preventing the growth of complex nitrides of CrNbN system, negatively affecting the impact toughness, by controlling the conditions of solidification at ESR has been established.

Heusler compounds are attracting tremendous attention due to their significant magnetoresistance, half-metallicity, and other properties which are used in spintronics, magnetooptical, memory devices, etc. [1]. We performed first-principal calculations for compound Co₂MnGa, taking into consideration antisite structural defects. Co₂MnGa without antisite defects was confirmed to be a topological Weyl compound. The exact electronic states at E Fermi are 1.8 st./eV/f.u. in the majority spin and 0.58 st./eV/f.u. in the minority spin. Hence, the spin polarization is 52%. The magnetic moments are 0.73 (Co) μ_B, 2.91 (Mn) μ_B and -0.15 (Ga) μ_B, and the total moment of Co2MnGa is 4.22 μ_B, which is in good agreement with the experimentally reported moment of 4.05 μ_B, which corresponds to the accuracy of our theoretical calculation being as high as 96%, it was previously calculated to be between 3.07 and 4.21 μ_B [1]. For the Co1-Mn antisite defect, the magnetic moment decreases to 1.07 μ_B; for the Co2-Ga replacement, the magnetic moment is 1.85 μ_B. However, for the Co2-Mn antisite replacement, the total magnetic moment reaches up to 5.89 μ_B. Thus, the antisite defects in Co₂MnGa result in different changes in the magnetic moments and metallic properties, following from the densities of electron states calculated in our study.

1. Elphick, K.; Frost, W.; Samiepour, M.; Kubota, T.; Takanashi, K.; Sukegawa, H.; Mitani, S.; Hirohata, A. Heusler alloys for spintronic devices: review on recent development and future perspectives. STAM 2021, 22, 1, 235–271.https://doi.org/10.1080/14686996.2020.1812364

AlCoCrFeNi2.1 eutectic high-entropy alloy stands out for its remarkable mechanical properties, offering an excellent balance between strength and plasticity. For the first time, gas tungsten arc welding (GTAW) was applied to this as-cast alloy to investigate its weldability and associated microstructural evolution. A comprehensive analysis of the welded joint’s microstructure was performed using electron microscopy, electron backscatter diffraction (EBSD), synchrotron-based X-ray diffraction (SXRD), and thermodynamic simulations. The alloy's mechanical properties were characterized through microhardness mapping and tensile testing, which was integrated with digital image correlation (DIC) to provide insights into local deformation behavior. The welded joint, comprising the base material (BM), heat-affected zone (HAZ), and fusion zone (FZ), retained a eutectic structure with FCC and B2-type BCC phases. Variations in phase proportions arose due to thermal cycling during welding. BCC nanoprecipitates present in the BM were partially dissolved near the FZ boundary within the HAZ. Grain refinement in the FZ, driven by rapid solidification, contributed to increased hardness in this region. Despite these microstructural changes, tensile testing showed that the joints exhibited a favorable balance between strength and ductility, with failure consistently occurring in the BM. This work highlights the feasibility of using arc-based welding methods for high-entropy alloys, underscoring their potential for advanced structural applications.

Since their inception, high-entropy alloys (HEAs) have been the subject of an increasing amount of research involving a plethora of compositions and environmental conditions. In line with this, research on their processability is crucial to achieve competitive alternatives to common engineering alloys for potential structural and functional applications. For such endeavors, gas tungsten arc welding (GTAW), which is widely used in industry to obtain monolithic parts from separate components, is capable of supplying pertinent information regarding the feasibility of combining new materials in terms of their microstructure and mechanical performance.

With this in mind, in the present work, we present an analysis of the feasibility of GTAW of CoCuFeMnNi HEA. This is accomplished by delving into microstructural observations using conventional and advanced techniques, such as synchrotron X-ray diffraction coupled with CalPhaD-based calculations, to fully comprehend the microstructure across the weld. The mechanical performance of the joints is also researched in terms of microhardness and tensile testing.

Overall, the dual-phase nature of the HEA is observed throughout the welded joint, where the nucleation of a B2 BCC phase is highlighted in the heat-affected zone. The obtained joints however, exhibit poor mechanical performance, which is attributed to the residual stresses and sizeable grains which develop within the solidifying molten pool.

We introduce a new concept and a potentially general platform for the purification of immunoglobulins that does not rely on any resins, chromatographic media, membranes, or specific ligands; rather, it makes use of aromatic [metal—chelator] complexes. A hydrophobic chelator is combined with three different metal ions to establish our purification system. We experimented on the purification of IgG, IgM, and IgA, along with an artificial impurity background. Our impurity background contained 2600 proteins, along with 600 membrane proteins. Our system captured the target immunoglobulins quantitatively via [cation—pi] and [pi—pi] interactions and allowed for their recovery at high yields (80% to 88%, by densitometry) and purity (90% to 96%, by SDS-PAGE), while preserving their secondary structure (by circular dichroism, CD, and native PAGE gel electrophoresis) and monomeric state (by dynamic ligand scattering, DLS). The entire process was performed at pH 6-7, thereby avoiding complications that derive from exposure to harsh acidic conditions (e.g., aggregation, partial denaturation). The potential to upscale the technology was evaluated at the laboratory scale. The leaching of the metal—chelator complex to the eluted antibodies was assessed and found to be less than 1%. The recycling of the chelator after the purification process generated a satisfactory yield of 95-97% . The cost-effectiveness and simple integration into the future, industrial-scale downstream processing of therapeutic-grade biopharmaceuticals is discussed.

This study examines the feasibility of using friction stir welding (FSW) to join laser powder bed fusion (LPBF) additively manufactured Scalmalloy®, A20X, and CuNiSiCr copper alloys. Additively manufactured aluminum and copper alloys are highly valued for their ability to produce complex geometries. However, challenges such as printability issues, defect management, and the limited production volumes achievable with standard LPBF machines contribute to hindering their large-scale adoption. Consequently, researchers are increasingly exploring welding techniques for joining additively manufactured components. While fusion welding introduces challenges related to melting and solidification, solid-state welding methods like FSW offer significant advantages by preserving the engineered microstructures of these materials.

This research investigates the effects of FSW on the quality of butt joints made from 4 mm thick LPBF-manufactured plates of A20X, Scalmalloy®, and CuNiSiCr. A range of rotational and welding speeds was tested to evaluate the influence of the joining process on the mechanical properties and microstructures of these alloys. For the aluminum alloys, FSW produced welds with refined microstructures and only minimal reductions in mechanical strength compared to the base material. In contrast, the CuNiSiCr alloy demonstrated an increase in strength after welding, attributed to the fine-grained microstructure in the stir zone compared to the coarse-grained base material. Furthermore, 3D X-ray computed tomography revealed that metal stirring during the FSW process significantly reduced the intrinsic porosity across all the tested alloys. The study also evaluated hardness profiles, joint appearance, and fractographic analyses, highlighting a strong correlation between microstructural features and mechanical performance. These findings underscore the potential of FSW as an effective joining method for LPBF-manufactured components.

The biocompatibility and durability of titanium alloys, such as Ti-6Al-4V, are critical for their performance in biomedical applications. However, their susceptibility to corrosion in physiological environments remains a challenge. This study explores the synthesis and application of alginate-based hydrogels loaded with copper oxide nanoparticles (CuO NPs) as a protective coating on untreated and SLA-treated Ti-6Al-4V substrates. Alginate, a biopolymer with high hydrophilicity and biocompatibility, was selected for its potential to create a uniform hydrogel layer, while CuO NPs were incorporated for their known antimicrobial and corrosion-inhibitory properties. SLA treatment was employed to enhance surface roughness, promoting hydrogel adhesion.

The synthesized hydrogels were characterized using FTIR, confirming the successful incorporation of CuO NPs. Adhesion testing demonstrated superior hydrogel attachment to SLA-treated titanium surfaces due to increased surface roughness and energy. Corrosion resistance was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in a simulated body fluid. The results revealed significant improvement in corrosion resistance for the hydrogel-coated samples compared to bare titanium, with the CuO NP-loaded hydrogels exhibiting the highest protection. This enhancement is attributed to the hydrogel's barrier properties, which limit ion diffusion and reduce electrolyte access to the metal surface, counteracting the expected corrosion-promoting effect of a wet environment.

This research highlights the potential of SLA-treated, CuO NP-enriched alginate hydrogels to improve the longevity and performance of titanium implants by addressing both biocompatibility and corrosion resistance challenges.

The use of titanium (Ti) and its alloys (particularly Ti6Al4V, or simply Ti64) to additively manufacture implants for tissue engineering in the biomedical field has seen a steep rise in recent years. Titanium is the preferred metal for bioengineering applications due to its outstanding specific strength, biocompatibility, and corrosion resistance. Additive manufacturing (AM, also known as 3D printing) provides unchallenged freedom for designers, allowing them to fabricate custom objects while maintaining a short turnaround time. The layer-by-layer production nature of 3D printing techniques, such as direct metal laser sintering (DMLS), has been successfully utilized by the medical industry to manufacture complex shapes using biocompatible materials in order to produce implants. The drawback of Ti and its alloy is that they do not innately possess antibacterial properties and may attract bacterial attachment because of their biocompatibility. Copper (Cu) is an essential mineral which displays a highly efficient antibacterial effect. Thus, alloying Ti-based implant material with Cu particles induces a bactericidal feature in such biomaterials. This paper describes the DMLS manufacturing of in situ alloyed commercially pure titanium (cpTi) and Ti6Al4V ELI with Cu and the examination of their microstructure. Studying the microstructure of 3D-printed parts is essential for predicting their mechanical properties and functionality.