Search Results (534)

Carrying out a series of fundamental studies in the field of physicochemical analysis, based on an approach that considers the phase state of alloys and accounts for the regular patterns of interaction of substances in multicomponent ores that are complex in both chemical and phase composition, makes it possible to formulate a number of scientifically substantiated practical recommendations. The aim of this work is to assess the degree of zinc sublimation from a magnesium alloy through the behavior of the Bjerrum–Guggenheim osmotic coefficient and the degree of dissociation of the congruent compound. The paper presents a method for processing phase equilibrium lines in a temperature–composition phase diagram, resulting in mathematical expressions for the liquidus and solidus lines on a unified analytical basis in the form of a semi-empirical dependence derived from the Schröder–Le Chatelier equation. Indirectly, through the Bjerrum–Guggenheim osmotic coefficient, the degree of dissociation of MgZn₂ in the Mg–Zn system was determined to range from 17% to 46%. This result is in good agreement with the conclusions of Nikolay Semyonovich Kurnakov regarding the degree of dissociation of congruent compounds inferred from the shape of the maximum on phase diagrams. For MgZn₂, this maximum is very smooth, i.e., the composition of the liquid phase changes continuously with deviation from stoichiometry, resulting in a symmetrical rounded peak. An experimental study was carried out using a SEM/EDS analytical complex to confirm the high volatility of zinc. The key zinc-concentrating phases were identified in the investigated processing products (slag, metal, and dust), which is consistent with the theoretical premises and explains the mechanism of zinc behavior during high-temperature processing of zinc-containing slags. The form of zinc occurrence in different phases was established. In the initial slag, the zinc content reaches 51.79%. In the metallic phase, zinc is detected as fine dispersed inclusions. In the collected dust (flue ducts), particles enriched in zinc up to 44.09 wt.% were identified. Full article

Titanium alloys are widely used for implants, yet corrosion, bacterial colonization and incomplete osseointegration remain important causes of interfacial failure. This review critically analyzes major biomedical functional coating fabrication techniques employed to enhance the surface properties of titanium alloys, including micro-arc oxidation, anodic oxidation, magnetron sputtering, electrochemical deposition, electrophoretic deposition, plasma spraying, physical vapor deposition, plasma immersion ion implantation, laser surface treatment, and hybrid (composite) approaches. For each method, key operational principles, structural and functional characteristics, performance advantages and limitations, and representative application domains are critically analyzed. Across these routes, biological performance depends on coating continuity, pore or nanotube geometry, interfacial bonding, phase composition and ion release. Calcium- and phosphorus-rich oxides and hydroxyapatite deposits generally promote cell adhesion, proliferation, alkaline phosphatase activity, mineralization and osteogenic differentiation. Dense oxide, nitride, tantalum and carbon-based films strengthen corrosion barriers, whereas Mn, Zn, Cu and Ag containing surfaces can inhibit bacterial adhesion and biofilm formation. Excessive ion release, however, may compromise cytocompatibility. Reported outcomes also vary with test medium, exposure time, bacterial strain and cell model. Standardized quantitative endpoints and longer-term corrosion, biofilm and osseointegration studies are required to guide clinically reliable multifunctional coatings. Full article

The interfacial reaction between solder and substrate is a critical factor governing joint reliability, making it essential to understand the formation and stability of interfacial reaction layers when developing new high-temperature lead-free solders. This study investigates the interfacial reaction layers formed in Zn-5Al-3Mg solder/Cu substrate joints soldered at 693 K under vacuum. With a binary Zn-Al solder, the Cu substrate is progressively consumed by Zn, and the intermediate phases CuZn₄, Cu₅Zn₈, and CuZn nucleate and grow concurrently at the solder interface. The addition of a minor amount of Mg to the Zn-Al alloy, however, fundamentally alters this reaction sequence. Transmission electron microscopy analyses, including scanning transmission electron microscopy–energy-dispersive X-ray spectroscopy (STEM-EDS), energy-filtered TEM (EF-TEM), and electron diffraction, reveal three distinct interfacial layers: an outer Mg₂Zn₁₁ layer, a middle two-phase mixture of CuZn₄/Mg₂CuZn₃, and an inner Cu₅Zn₈ layer adjacent to the Cu substrate. The biphasic CuZn₄/Mg₂CuZn₃ mixture layer is shown to form via a quasi-peritectic reaction governed by sequential four-phase equilibria in the Zn-Mg-Cu ternary system. These findings demonstrate that minor Mg additions redirect the interfacial reaction pathway between Zn-Al-based solders and Cu substrates, providing new insight for the design of high-temperature Pb-free solder systems. Full article

The role of the Zn/Mg ratio in regulating microstructure, precipitation evolution and coarsening resistance in Al–Zn–Mg-based alloys was investigated by microhardness testing, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) during isothermal aging at 150 °C. Three alloy compositions were designed with Zn/Mg ratios of 1.6, 2.4, and 3.9, whereas the combined Zn and Mg level was fixed at 6.0 wt%. All alloys exhibited a typical age-hardening response, whereas the maximum peak hardness was obtained at an intermediate Zn/Mg level rather than at the two extremes. The optimal composition (Zn/Mg = 2.4) reached 137 HV, which is attributable to the formation of the finest precipitates (~3 nm) and the highest number density. Moreover, this alloy exhibited the smallest hardness loss (ΔH = 19 HV) after prolonged aging (192 h). TEM analysis indicated that this alloy exhibited the lowest coarsening rate constant, Kr = 0.43 at 192 h. Furthermore, the variation in Zn/Mg ratio affected grain boundary precipitation, leading to a minimized PFZ width at Zn/Mg = 2.4 while maintaining a similar discontinuous distribution of grain boundary precipitates among the alloys. Overall, tailoring the Zn/Mg balance offers an effective strategy to achieve refined precipitates, improved coarsening resistance, and enhanced mechanical performance with superior thermal stability. Full article

This study develops novel multicomponent Al–Mg–Si–Zr–Cu-based alloys for high-pressure die casting (HPDC) with improved mechanical properties and thermal stability. Four compositions were designed through Zn and Cr additions, supported by thermodynamic modelling. XRD and SEM/EDS analysed phase formation and microstructure, while density, electrical conductivity, hardness, and mechanical behaviour under tensile and compressive loading at room temperature and 200 °C were evaluated. Hardness increased from 166 to 214 HV3 with Zn and Cr due to the formation of complex intermetallic phases. The Al–Mg–Si–Zr–Cu alloy showed the best balance of strength and ductility under tensile loading, whereas Zn and Cr additions reduced tensile performance. In compression, Zn significantly improved strength, reaching the ultimate compressive strength of 697 MPa. Compared with the reference AlSi9Cu3 alloy, the new alloys achieved up to 30% higher yield strength, 13% higher ultimate tensile strength, and improved thermal stability. Among the studied compositions, Al72Mg10Si5Zr3Cu10 showed the best overall performance, while Al67Mg10Si5Zr3Cu10Zn10 was optimal for compression-dominated applications. Full article

In the aircraft industry, with the growing demand for advanced, sustainable structural materials, researchers are increasingly focusing on developing Al-Zn-Mg-Cu alloys, particularly the Al 7075 alloy with micro-alloying elements. However, load and environmental conditions pose problems for the aircraft industry by significantly reducing fleet service life. Thus, researchers are keen to use micro-alloying elements such as Ni, Ce, Ag, Sn, Ti, and Cd with the Al 7xxx base alloy to achieve enhanced mechanical properties, particularly hardness and tensile strength. Besides micro-alloying, the heat treatment (HT) process and cold working also have a favorable effect on the improvement of the mechanical properties. However, the addition of micro-alloying elements improves those properties more than HT and cold working processes. In this review study, several mechanical properties of the alloy have been comprehensively covered, which helps to establish a comparative analysis between the heat-treated base alloy and heat-treated micro-alloyed Al alloy. The base alloy, after micro-alloying, becomes enriched, with a high formability and workability, high conductivity, and good erosion protection that significantly make these alloys sustainable for the aircraft industry. The impact of dynamic changes accompanying the use of this lightweight alloy, after identifying the sensible necessities for the development of techniques, can effectively change the whole concept of the structural design. Hence, the key emphasis of the present review lies in a better understanding of the correlation between the structure and properties of micro-alloyed Al 7xxx alloy, which heralds a new era for aircraft industries. Full article

Single-pass differential speed rolling (DSR) is an effective route for strengthening magnesium alloys through grain refinement induced by dynamic recrystallization (DRX); however, the accompanying strong basal texture often limits ductility and formability. In previous work, an Mg–2Al–0.5Ca–0.4Mn alloy (namely AXM20504) in the T4 condition was subjected to single-pass DSR with thickness reductions of 20% and 40% with a preheat temperature of 400 °C and a roll temperature of 300 °C, followed by post-annealing at 350–450 °C for durations of 20–60 min to systematically investigate static recrystallization (SRX), texture evolution, and mechanical response. Electron backscatter diffraction (EBSD) revealed that post-annealing promoted progressive SRX, with nearly complete recrystallization achieved at 450 °C for 40 min. This transition was accompanied by substantial basal texture weakening, reduced kernel average misorientation (KAM), and significantly lower grain orientation spread (GOS), indicating effective stress relief and formation of strain-free grains. As a result, tensile ductility increased from ~5% in the 40% as-rolled condition to ~12% after optimized post-annealing, while ultimate tensile strengths were retained above 200 MPa, much higher than the initial T4 strength. While these findings demonstrate that post-annealing is a critical step in restoring ductility and enhancing the formability of DSR-processed Mg alloys, certain types of alloying can also assist in a favorable balance between strength and formability for sheet forming applications. Alloying with Zn has been shown to improve ductility to a higher than 20% elongation at break as compared to 5% for the T4 AXM base material, showing that processing techniques and alloying have a high impact on the formability of Mg-based alloys. The zinc-based alloys in this study include Mg-2Al-0.5Ca-0.4Mn-0.5Zn (namely AXMZ2050405) and Mg-2Al-0.5Ca-0.4Mn-1Zn (namely AXMZ205041), both of which demonstrated improvements in mechanical properties as compared to the base alloy, AXM20504. Full article

Diffusion solidification is an effective method to produce non-dendritic microstructures and reduce casting defects in magnesium alloys. However, the influence of precursor alloy superheat on the solidification behavior and the resulting microstructure remains insufficiently understood. In this study, pure magnesium was used as the high thermal mass (HTM) alloy and three Mg-Al-Zn alloys with different aluminum and zinc contents were used as the low thermal mass (LTM) alloys. The effects of superheat on grain morphology, solute diffusion, and constitutional supercooling were investigated through a combination of experimental casting and numerical simulation using Ansys Fluent and Matlab. The results show that the solidified interface consists of five distinct regions, including two base metals, two transition zones, and a central controlled diffusion solidification zone. A higher superheat of the HTM alloy relative to the LTM alloy promotes a wider transition zone and finer globular grains, whereas equal or lower superheat leads to columnar or rosette structures. The Mg-30 wt.%Al-3.5 wt.%Zn alloy with moderate aluminum content produces fine globular grains due to a thinner constitutional supercooling layer and a higher degree of supercooling, which suppresses grain growth and increases nucleation rate. In contrast, the Mg-55 wt.%Al-6.5 wt.%Zn alloy with high aluminum content forms coarse rosette and columnar grains. Among the conditions investigated, the combination of 10 °C HTM and 5 °C LTM superheats tends to promote the formation of fine equiaxed grains. Increasing superheat above this range reduces supercooling and coarsens grains, while decreasing superheat inhibits interface diffusion and promotes solute segregation. The findings provide a theoretical basis for designing precursor alloy compositions and superheat parameters in controlled diffusion solidification of magnesium alloys. Full article

This study reveals the synergistic effects of Mn and Zr microalloying and equal-channel angular pressing (ECAP) on the microstructure and corrosion behavior of Mg-Y-Zn alloys in Hanks’ solution. At moderate deformation levels (four passes), the alignment of LPSO phases forms semi-continuous barrier structures, promoting the formation of dense corrosion product layers and improving corrosion resistance. (e.g., Mg-Y-Zn-Mn 4p: 1.07 mm·y⁻¹). However, excessive deformation (eight passes) leads to severe fragmentation of LPSO phases, increasing cathodic activity and intensifying micro-galvanic coupling in Mn-containing alloys (Mg-Y-Zn-Mn 8p: 2.61 mm·y⁻¹). In contrast, Zr-containing alloys exhibit continuous improvement in corrosion resistance with increasing ECAP passes, attributed to enhanced electrochemical uniformity resulting from homogeneous ultrafine-grained structures (Mg-Y-Zn-Zr 8p: 0.87 mm·y⁻¹). These findings elucidate the critical mechanism by which the interplay between microalloying chemistry and severe plastic deformation governs electrochemical uniformity and corrosion kinetics. This work provides new insight into the corrosion behavior of ECAP-processed Mg-Y-Zn alloys, highlighting the critical role of balancing microstructural refinement and electrochemical heterogeneity, and offers guidance for the optimization of corrosion-resistant Mg-based materials. Full article

The release of aluminum (Al) and vanadium (V) ions represents a critical concern limiting the long-term performance and biocompatibility of Ti6Al4V-based permanent orthopedic implants. This study focuses on improving the corrosion resistance of Ti6Al4V alloys through the application of a novel organic–inorganic ZnO nanocoating. In addition, the present study investigated the influence of substrate roughness on surface morphology, microhardness, and wettability characteristics. Xanthan gum (XG) and celite (CE) were utilized as a biopolymeric–ceramic matrix for the ceramic–biopolymer-assisted synthesis of ZnO nanoparticles (ZnO NPs) through ultrasonication, which was subsequently followed by deposition onto Ti6Al4V substrates with varying surface roughness (Ra) achieved through controlled turning. The synthesized XG/CE-ZnO NPs exhibited a uniform spherical morphology with an average particle size of nearly 50 nm and a hexagonal wurtzite crystalline structure, as confirmed by TEM, XRD, and FTIR analyses. Contact angle (CA) measurements indicated that wettability increased with higher Ra, while SEM with energy-dispersive X-ray spectroscopy characterization revealed morphology transitions from smooth, homogeneous coatings to agglomerate, star-like nanostructures as Ra increased. Electrochemical testing in Ringer’s solution demonstrated a significant improvement in corrosion resistance after coating, with protection efficiencies ranging from 95.18% to 98.48%, particularly for smoother substrates. Although increased Ra may enhance coating adhesion through mechanical interlocking, smoother substrates promote the formation of more homogeneous coatings, resulting in superior corrosion protection. These results demonstrate the significant influence of substrate topography in enhancing the functional performance of biocompatible ZnO nanocoatings, providing valuable insights for the surface engineering of metallic implants. Full article

In this study, the microstructure, mechanical properties, and corrosion behavior of extruded Mg-Y-0.5Zn alloys with varying Y contents (0.5~3.0 wt%) were systematically investigated. The results demonstrate that by increasing the Y content from 0.5% to 3.0%, the grain sizes of four alloys are 11.27 μm, 11.90 μm, 15.26 μm, and 13.65 μm. The secondary phases of all four alloys consist of granular Mg₂₄Y₅ and fine Mg₁₂YZn, and the total volume fraction of these precipitates increased. Correspondingly, both microhardness and strength are enhanced, while ductility decreases. The microhardness increases from 57.1 HV to 61.7 HV, the tensile yield strength (TYS) improves from 103.8 MPa to 155.4 MPa, and the ultimate tensile strength (UTS) rises from 211.4 MPa to 235.9 MPa. Regarding corrosion performance, the extruded Mg-1Y-0.5Zn alloy exhibits the best corrosion resistance based on both in vitro immersion tests and electrochemical measurements. A uniform and dense corrosion product layer is observed on the surface of Mg-1Y-0.5Zn alloy, leading to the lowest corrosion rate of 0.36 mm/y, while loose and micro-cracked corrosion product layers are formed on other alloys. In addition, cytotoxicity test shows that the relative cell proliferation rates of the four extruded alloys were 121.41%, 123.7%, 117.96%, and 112.86%, indicating good biocompatibility. Full article

This study investigates the effect of SiC nanoparticle addition on the microstructure, interfacial reactions, and mechanical properties of Zn5Al3Ti active solder used for ultrasonic soldering of AlN ceramic to copper substrates. Composite solders containing 3 and 6 wt.% SiC nanoparticles were prepared and applied under flux-free ultrasonic soldering conditions. The solder alloys were evaluated by tensile testing, while the soldered joints were evaluated by shear strength testing. The solder microstructure and interfacial regions were characterized using SEM/EDS analysis. The results showed that the addition of SiC nanoparticles modified the microstructure of the Zn5Al3Ti solder and influenced the mechanical performance of the ceramic/metal joints. Among the investigated systems, the AlN/Zn5Al3Ti + 6 wt.% SiC/Cu joint exhibited the highest shear strength, reaching approximately 101 MPa. SEM/EDS observations revealed the formation of compact multilayered interfacial regions, including possible Cu–Zn intermetallic phases at the Cu/solder interface and Al–Ti–Zn-based reaction products near the solder/AlN interface. The improved joint performance may be attributed to the combined effect of SiC-induced microstructural modification, the presence of Si-containing particles, and the formation of compact metallurgical bonds. The results indicate that Zn5Al3Ti solder modified with 6 wt.% SiC nanoparticles is a promising material for producing strong AlN/Cu joints under the applied ultrasonic soldering conditions. Full article

Due to fractures in young and mature people, combined with aging and other factors increasing year by year, there is a demand for new materials to efficiently address fracture-healing-related issues. There are designs of new biodegradable Zn-based alloys whose chemical composition provides new opportunities to manufacture medical devices for supporting and assisting bones in their healing processes. To achieve this goal, it is well known that a strength–ductility balance and appropriate degradation are required. In this context, it is vital to know and understand how the addition of elements modifies the as-cast microstructure, which is the basis of further processing steps such as heat treatment and thermomechanical processing. In the present work, a broad characterization was performed of two as-cast hypoperitectic Zn-Ag-based alloys with Mg and Cu additions. First, cooling curves were presented, and a dissertation regarding the temperature appearance of their secondary phases was made. Also, XRD and SEM-EDS techniques were performed, and their mechanical and corrosion performance was analyzed to elucidate which third element is the best option for intended orthopedic applications. Full article

The development of eco-friendly magnesium (Mg)-based materials that possess acceptable mechanical properties, good biodegradability, and non-toxicity in biomedical applications has become more attractive in recent years, particularly for engineering and biomedical applications. This work investigates the effects of nano-ZnO (2 wt.%) reinforcement and cryogenic treatment (CT) on the microstructural, mechanical, thermal, and corrosion behavior of a non-toxic Mg-1Zn-1Ca alloy. Disintegrated melt deposition (DMD) was the synthesis starting point, while refrigeration at −20 °C (RF20) and liquid-nitrogen exposure at −196 °C (LN) were employed as the CT methods. CT significantly refined the grain size of the alloy and composite materials by more than 31.3%, down to 4.4–4.5 μm in diameter, leading to enhanced mechanical performance through grain boundary strengthening. RF20-treated Mg-1Zn-1Ca alloy exhibited the best damping properties (attenuation coefficient and damping capacity improved by 52.1% and 48.7%, respectively). Compressive response was also improved due to the combined effect of refined grains and reinforcement, with LN-treated Mg-1Zn-1Ca-2ZnO exhibiting the best combination of compression properties, i.e., YS—165 MPa, UCS—634 MPa, ε—43.6%, and W_f—175 MJ/m³. Ignition resistance was also improved with the addition of ZnO reinforcement (3.8% increase in ignition temperature). A significant reduction in corrosion rate was achieved with RF20 treatment, leading to corrosion rate reductions of 62% and 40% in PBS (simulated human body fluid) and salt solution, respectively, primarily due to equiaxed grains and stable microstructure. These results demonstrate the efficacy of ZnO reinforcement and CT conducted at different temperatures in selectively enhancing and tailoring the properties of eco-friendly, biocompatible Mg-alloys and composites for biomedical and strength-based applications. Full article

The work is a continuation of studies , focused on the development of fundamental principles of aluminum activation by low-melting metals forming eutectic alloys with fine-grained structure and limited solid solubility. The aim of this work is to investigate the mechanism and kinetics of the interaction of aluminum-based eutectic alloys with water and aqueous electrolytes. Analysis of phase diagrams of binary systems (Al–Ga, Al–In, In–Ga, Al–Sn, Sn–Ga, Al–Zn, Zn–Ga) shows that alloy composition governs surface heterogeneity and reactivity. Ternary and quaternary systems (Al–In–Ga, Al–Sn–Ga, Al–In–Sn–Ga) exhibit enhanced interaction with water due to increased heterogeneity, leading to the formation of numerous microgalvanic couples and accelerated aluminum dissolution. The process is characterized by the stationary potential of aluminum and involves coupled chemical, electrochemical, and topochemical stages described by the Avrami–Erofeev equation, with n ≈ 1.27–2.07. An increase in the In–Ga or In–Sn–Ga fraction reduces the activation energy: 9.1 kcal/mol (82% Al–9% Ga–9% Sn), 11.4 kcal/mol (92% Al–4% Ga–4% In), and 15.5 kcal/mol (91% Al–3% Ga–3% In–3% Sn). Full article