Search Results (1,909)

In physiological environments, several metallic alloys, including titanium, stainless steel, cobalt–chromium, and emerging biodegradable systems such as magnesium (Mg), zinc (Zn), and iron (Fe), offer mechanical properties and biocompatibility suitable for load-bearing implants. With the rapid advancement of 3D printing technologies, these alloys can now be fabricated into patient-specific, complex geometries that enhance both structural performance and functional integration. Beyond serving as structural supports, 3D-printed alloys are increasingly engineered as localized drug-delivery platforms to release anti-inflammatory, antibacterial, anticancer, and osteogenic agents at the implant–tissue interface, addressing the dual clinical needs of site-specific therapy and mechanical stabilization. Nevertheless, this field remains underexplored because studies differ widely in alloy chemistry, surface topography, porosity, coating strategy, drug-loading methods, and release profiles, as well as in how material degradation or passivation interacts with pharmacokinetics. For the first time, this review consolidates drug-loading and elution strategies across 3D-printed alloy platforms, compares therapeutic categories in relation to alloy and coating types, and critically evaluates how the surface microstructure or alloy geometry influences release behavior. Full article

Against the backdrop of continuously expanding global magnesium alloy applications and surging scrap generation, achieving efficient recycling and low-carbon regeneration of magnesium alloys has emerged as a key pathway for advancing green transformation in manufacturing. The AM50A recycled magnesium alloy was selected as the research subject, employing the attributional life cycle assessment (ALCA) methodology to systematically calculate its “cradle”-to-“gate” carbon footprint across three stages: raw material acquisition, transportation, and production. The results indicate that the carbon footprint of AM50A recycled magnesium alloy is 4.9399 kg CO₂e/kg, with the production stage accounting for a significant 99.34% of emissions, identified as the primary source. The combined contribution from raw material acquisition and transportation stages is only 0.66%. Compared to magnesium alloys produced by the Pidgeon process, greenhouse gas (GHG) emissions can be reduced by approximately 67.56% through the recycling process, highlighting its significant advantages in promoting low-carbon manufacturing and circular economic development for magnesium alloys. This study provides data support for the environmental performance assessment of recycled magnesium alloys and offers a scientific basis for optimizing energy conservation and emission reduction pathways in related industries. Full article

The Zn-3Mg alloy fabricated by laser powder bed fusion (LPBF) additive manufacturing is widely used in biomedical implants due to its excellent biocompatibility and favorable mechanical strength. However, its application is hindered by limited ductility and a relatively rapid degradation rate. This study investigated the influence of annealing heat treatment on the microstructure, mechanical properties, and degradation behavior of LPBF-fabricated Zn-3Mg porous implants. A systematic analysis of various annealing parameters revealed the evolution mechanisms of the microstructure, including grain coarsening and the precipitation and distribution of secondary phases Mg₂Zn₁₁ and MgZn₂. The results indicated that appropriate annealing conditions (such as 250 °C for 1 h) significantly enhanced the compressive strain by 10%, while maintaining a high compressive strength of 24.72 MPa. In contrast, excessive annealing temperatures (e.g., 365 °C) promoted the formation of continuous brittle phases along grain boundaries, leading to deterioration in mechanical performance. The degradation behavior analysis illustrated a substantial increase in the corrosion rates from 0.6973 mm/year to 1.00165 mm/year after annealing at 250 °C for 0.5 h and 365 °C for 1 h, which can be attributed to the micro-galvanic effect induced by the presence of fine or coarse secondary phases that promoted localized corrosion. This study demonstrated synergistic regulation of mechanical properties and degradation behavior in the Zn-3Mg porous structures through optimized heat treatment, thereby providing essential theoretical and experimental supports for the clinical application of biodegradable zinc-based implants. Full article

This study systematically optimizes the T6 heat treatment of a commercial EV31A magnesium alloy and evaluates the resulting microstructural evolution and mechanical properties. Optical microscopy, scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to characterize the microstructure and phase constitution, while differential scanning calorimetry (DSC) was employed to determine appropriate solution treatment parameters. Brinell hardness measurements and tensile tests at room temperature and 150 °C were carried out to quantify the mechanical response. The as-cast alloy consists of α-Mg equiaxed grains, bone-shaped Mg₁₂(Nd,Gd) eutectic phases at grain boundaries, and minor intragranular lath-shaped Mg₁₂Nd phases. After T6 treatment (520 °C/10 h solution treatment + 200 °C/16 h aging), the grain boundary eutectic phases partially dissolve and transform into Mg₄₁(Nd,Gd)₅, while intragranular nano-scale β′ precipitates and stable Zn₂Zr₃ particles form, achieving multi-scale synergistic strengthening. Compared to the as-cast condition, the T6-treated alloy exhibits room-temperature ultimate tensile strength and yield strength of 309 ± 40.5 MPa (31% increase) and 180 ± 14.2MPa (45% increase), respectively. At 150 °C, the strength reaches 241 ± 7.5 MPa (39% increase) and 154 ± 16.8 MPa (52% increase), while maintaining an elongation of 10.9± 0.7%, demonstrating an excellent strength–ductility balance. Full article

This study addresses the issue of adapting the thermal drilling process for joining dissimilar thin-walled materials—sheets made of non-ferrous metal alloys and polymer composites with a thermoplastic matrix reinforced with glass and carbon fibers—without the use of connecting elements and without disrupting the continuity of the reinforcing fibers. An extensive metallographic study was conducted on bushings formed in thin metal sheets made of EN AW 6082 T6 aluminum alloy and AZ91 magnesium alloy obtained during separate drilling procedures. Experiments were also performed where the metal sheet and composite material overlapped, using both direct and sequential drilling above the melting point of the polymer matrix, applying various process parameters. The dimensions of the resulting bushings and the suitability of their profile for joining with composites were evaluated. The results suggest the possibility of joining metals and fiber composites through thermal drilling, and suitable joining process parameters and conditions are specified. To limit composite delamination, it is advisable to make a hem flange on the reverse side of the joints. CT scans confirmed the deflection of fibers around the hole in the composite without compromising their integrity. The load-bearing capacity of the joints and the possibility of creating hybrid mechanical–adhesive joints between these materials are the subject of Part Two of this study. Full article

Magnesium alloys are promising biodegradable orthopedic implant materials, but their clinical translation is hindered by rapid, unregulated corrosion in physiological environments. Polyvinylidene fluoride (PVDF) coating has attracted substantial attention for addressing the issue above. However, it suffers from insufficient interfacial adhesion to Mg alloy substrates. In this work, we propose a Zr-based pretreatment strategy to enhance PVDF coatings. The pretreatment was performed via a chemical conversion deposition method, which fabricated a Zr-based film on AZ31 magnesium alloy and greatly promoted the adhesion of the following PVDF coating. Interface analysis showed that coating adhesion was improved from 0.44 MPa to 2.48 MPa. In light of this, corrosion protection performance was significantly improved. Electrochemical tests in simulated body fluid revealed the enhanced PVDF coating shifted the corrosion potential from −1.594 V to −1.392 V and reduced the corrosion current density by over five orders of magnitude. Immersion tests also showed stable pH level, low weight loss, and good hydrophobicity with the enhanced PVDF coating. In summary, the enhanced PVDF coating provides excellent corrosion protection for magnesium alloys, thus boosting their biomedical use. Full article

A roller straightening process of a pure magnesium strip, accompanied by alternating elastic-plastic deformation, was performed through one and three passes, where one pass corresponded to 19 bending events. It was discovered that roller straightening leads to the appearance of a kink in the specimen’s tensile stress–strain curve as well as an almost twofold decrease in the yield stress. This effect was observed only on longitudinal specimens. The conducted EBSD analysis confirmed the previously stated hypothesis about the influence of twinning on the change in the shape of the roller-straightened magnesium alloy specimen’s stress–strain curve. The tensile twins {$10\overline{1}2$} formed during roller straightening facilitate the detwinning process during subsequent tensile deformation, which, along with the basal sliding, is the reason for the decrease in yield stress. The scaling factor of the tensile specimens was investigated. Full article

Simplex-centroid mixture design (SCMD) is applied to change the combination of Na₂SiO₃, KF, NaOH and NaAlO₂ to examine the influences of electrolyte components and their interactions on the thickness and corrosion resistance of micro-arc oxidation (MAO) coating of AZ91D magnesium alloy. The results indicate that the obtained regression equations are very significant (p-value < 0.01) and have high prediction accuracy (R² = 0.9893, 0.9989). Pareto analysis shows that the interactions effect between Na₂SiO₃, KF and NaAlO₂ on the coating thickness and corrosion resistance are 70.03% and 92.35%, respectively, which quantitatively confirms that there are interactions among electrolytes. The analysis of response surface methodology (RSM) demonstrates that the optimum formula is high concentration of Na₂SiO₃, high concentration of KF and low concentration of NaAlO₂. When Na₂SiO₃ is compounded with NaAlO₂, the two will react to form aluminosilicate colloids, resulting in increased viscosity of the electrolyte, and the coating corrosion resistance is poor. When the main salt of electrolyte is single Na₂SiO₃ or NaAlO₂, the corrosion resistance is better. KF can significantly improve the coating thickness and corrosion resistance. Pearson correlation coefficient (PCC) reveals that there is a remarkable relationship between thickness and the corrosion resistance in acidic media (r = 0.88927), which was determined by the corrosion mechanism of the latter. Full article

The present study examined the microstructure and corrosion characteristics of MgCa4Zn1Gd1 and MgCa2Zn1Gd3 alloys that were coated with ZnO thin films, which were deposited by atomic layer deposition (ALD). Coatings of different thicknesses (42.5, 95.4 and 133.7 nm for 500, 1000, and 1500 cycles, respectively) were characterized using X-ray diffraction (XRD), Raman spectroscopy, SEM/EDS, AFM (atomic force microscope), and FTIR (Fourier transform infrared spectroscopy). XRD and Raman analyses were conducted to verify the formation of crystalline zinc oxide (ZnO) with a homogeneous granular morphology. Surface roughness decreased with increasing coating thickness, reaching the lowest values for the 1500-cycle ZnO layer on MgCa2Zn1Gd3 (R_a = 7.65 nm, R_s = 9.8 nm). Potentiodynamic and immersion tests in Ringer solution at 37 °C revealed improved corrosion resistance for thicker coatings, with the lowest hydrogen evolution (20.89 mL·cm⁻²) observed for MgCa2Zn1Gd3 coated after 1500 cycles. Analysis of corrosion products by FTIR identified Mg(OH)₂ and MgCO₃ as dominant and then MgO and ZnO. Phase analysis also indicated the presence of ZnO coating after 100 h of immersion. The ZnO film deposited after 1500 ALD cycles on MgCa2Zn1Gd3 provides the most effective corrosion protection and is a promising solution for biodegradable magnesium implants. Full article

Multi-objective Bayesian Optimization (MOBO) has become a promising strategy for accelerating process development in Laser Powder Bed Fusion of Metals (PBF-LB/M), where experimental evaluations are costly, and design spaces are high-dimensional. This study investigates how different initialization strategies affect MOBO performance in a discrete, machine-limited parameter space during the fabrication of AZ31 magnesium alloy. Three approaches to constructing the initial experimental dataset—Latin Hypercube Sampling (V1), balanced-marginal selection (V2), and prior fractional-factorial sampling (V3)—were compared using two state-of-the-art MOBO algorithms, DGEMO and TSEMO, implemented within the AutoOED platform. A total of 180 samples were produced and evaluated with respect to two conflicting objectives: maximizing relative density and build rate. The evolution of the Pareto front and hypervolume metrics shows that the structure of the initial dataset strongly governs subsequent optimization efficiency. Variant V3 yielded the highest hypervolumes for both algorithms, whereas Variant V2 produced the most uniform Pareto approximation, highlighting a trade-off between global coverage and structural distribution. TSEMO demonstrated faster early convergence, whereas DGEMO maintained broader exploration of the design space. Analysis of duplicate experimental points revealed that discretization and batch selection can considerably limit the effective search diversity, contributing to an early saturation of hypervolume gains. The results indicate that, in constrained PBF-LB/M design spaces, MOBO primarily serves to validate and refine a well-designed initial dataset rather than to discover dramatically new optima. The presented workflow highlights how initialization, parameter discretization, and sampling diversity shape the practical efficiency of MOBO for additive manufacturing process optimization. Full article

This review highlights the significance of modern quantum-beam techniques, particularly neutron and synchrotron radiation sources, for advanced microstructural characterization of metallic systems. Following a brief introduction to neutron and synchrotron diffraction, selected studies demonstrate their application in probing thermally induced structural evolution in plastically deformed metals. Additively manufactured CoCrFeNi alloys and 316L stainless steels subjected to high-pressure torsion (HPT) were investigated by in situ neutron diffraction during heating, revealing the sequential regimes of recovery, recrystallization, and grain growth. Coupled with mechanical measurements, the results show that HPT followed by controlled thermal treatment improves the mechanical performance, offering strategies for designing engineering materials with enhanced properties. The thermal anisotropy behavior of Ti-45Al-7.5Nb alloys under in situ neutron diffraction is defined as anisotropic ordering upon heating, while the HPT-processed alloy displayed isotropic recovery of order at earlier temperatures. Complementary in situ synchrotron studies in rolled-sheet magnesium alloys unveiled microstructural rearrangement, grain rotation, recovery, and precipitate dissolution during annealing. And phase transformation, recovery, and recrystallization processes were detected in steel using HEXRD. This work emphasizes the complementary strengths of the neutron and synchrotron methods and recommends their broader application as powerful tools to unravel microstructure–property relationships in plastically deformed metals. Full article

This study investigated the corrosion behavior of cold-drawn Cu-0.43 wt% Mg alloy wires, which were intended for high-speed railway contact lines, under varying temperature (30–50 °C) and relative humidity (85% and 93%) conditions in controlled humid heat environments. The corrosion resistance of the alloy wires after 48 h of humid heat testing was evaluated using electrochemical methods such as polarization curves and electrochemical impedance spectroscopy. The morphology and composition of the corrosion products were characterized using scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results demonstrated superior corrosion resistance for specimens exposed to higher temperature and lower humidity (50 °C, 85% RH), as evidenced by lower corrosion current densities and higher film/charge transfer resistances compared to lower temperature and higher humidity conditions (30 °C, 93% RH). This enhanced resistance correlated with the formation of denser, more continuous protective corrosion films observed under high-temperature and low-humidity conditions. Surface analyses confirmed that the corrosion films consisted primarily of copper oxides (Cu₂O and CuO), with only trace amounts of magnesium oxides detected, suggesting Mg played a minor role in the composition of the mature passive film under these conditions. These findings provide crucial data on the environmental degradation behavior of Cu-Mg contact wires, which is particularly relevant for applications in coastal or humid regions. Full article

A thin-walled product made of AZ31 magnesium alloy was successfully fabricated using wire-feed electron-beam additive manufacturing. The microstructure of the initial wire, used as a precursor, comprises a α-Mg(Al, Zn) solid solution and a minor amount of the Al₈Mn₅ intermetallic phase. The microstructure of the as-printed AZ31 alloy exhibits a three-phase structure: α-Mg(Al, Zn), Al₈Mn₅, and β-Mg₁₇Al₁₂. It was proposed that the secondary β-phase was formed via a primary solidification process upon the cooling of the welded layers. The texture effect was evident in the <01$\overline{1}$2> direction, corresponding to the printing direction, while other crystallographic orientations demonstrated near-equal pole densities as the XRD lines. The yield strength for the as-printed alloy was found to be 86 MPa; the tensile strength reached 240 MPa; and the relative elongation was 21.5%. For the first time, the corrosion resistance of an EBAM-fabricated AZ31 alloy was studied. It was revealed that the corrosion current density in the referenced as-cast and as-printed alloys was below 2·10⁻⁴ A/cm². Full article

By tuning the extrusion parameters, the corrosion performances of as-extruded Mg-0.5Zn(-0.2X) alloys (X: Ca/Sr/Ag/In/Cu, denoted as Z05, Z0502-Ca, Z0502-Sr, Z0502-Ag, Z0502-In and Z0502-Cu, respectively) with similar grain sizes were investigated and compared with their as-cast counterparts. The formed Fe-Si precipitates after hot processing significantly accelerate the corrosion rates of Z05, Z0502-Ag and Z0502-In, whereas the driving force from the Fe-encapsulated MgCaSi(Fe) and MgSrSi(Fe) precipitates are not as strong in Z0502-Ca and Z0502-Sr. Impacts from Fe impurity in Z0502-Cu are masked in the fast corrosion due to the noble Mg2Cu intermetallics. Fe precipitation during hot processing is critical for micro-alloyed systems, as the changes in intermetallic/impurity distributions impact the corrosion performances profoundly. The enthalpy of formation and the potential difference are the key factors that influence the distribution of precipitate during hot processing. Full article