Search Results (156)

Background and Objectives: Magnesium (Mg)-based materials, such as the WE43 alloy, show potential in biomedical applications owing to their advantageous mechanical properties and biodegradability; however, their quick corrosion rate and hydrogen release restrict their general clinical utilization. This study aimed to develop a novel Mg-Zn-Ca alloy system based on WE43 alloy, evaluating the influence of Zn and Ca additions on microstructure, mechanical properties, cytocompatibility, and electrochemical behavior for potential use in biodegradable orthopedic applications. Materials and Methods: The WE43-Zn-Ca alloy system was developed by alloying standard WE43 (Mg–Y–Zr–RE) with 1.5% Zn and Ca concentrations of 0.2% (WE43_0.2Ca alloy) and 0.3% (WE43_0.3Ca alloy). Microstructural analysis was performed utilizing scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDS), while the chemical composition was validated through optical emission spectroscopy and X-ray diffraction (XRD). Mechanical properties were assessed through tribological tests. Electrochemical corrosion behavior was evaluated using potentiodynamic polarization in a 3.5% NaCl solution. Cytocompatibility was assessed in vitro on MG63 cells using cell viability assays (MTT). Results: Alloys WE43_0.2Ca and WE43_0.3Ca exhibited refined, homogeneous microstructures with grain sizes between 70 and 100 µm, without significant structural defects. Mechanical testing indicated reduced stiffness and an elastic modulus similar to human bone (19.2–20.3 GPa), lowering the risk of stress shielding. Cytocompatibility tests confirmed non-cytotoxic behavior for alloys WE43_0.2Ca and WE43_0.3Ca, with increased cell viability and unaffected cellular morphology. Conclusions: The study validates the potential of Mg-Zn-Ca alloys (especially WE43_0.3Ca) as biodegradable biomaterials for orthopedic implants due to their favorable combination of mechanical properties, corrosion resistance, and cytocompatibility. The optimization of these alloys contributed to obtaining an improved microstructure with a reduced degradation rate and a non-cytotoxic in vitro outcome, which supports efficient bone tissue regeneration and its integration into the body for complex biomedical applications. Full article

This work systematically investigates the Zn-content-dependent phase evolution (1–12 at.%) and its correlation with mechanical properties in as-cast Mg–2Y–xZn alloys. A sequential phase transformation is observed with the Zn content increasing: the microstructure evolves from X-phase dominance (1–2 at.% Zn) through W-phase formation (3–6 at.% Zn) to I-phase emergence (12 at.% Zn). Optimal mechanical performance is attained in the 2 at.% Zn-containing alloy, with measured tensile properties reaching 239 MPa UTS and 130 MPa YS, while maintaining an elongation of 12.62% prior to its gradual decline at higher Zn concentrations. Crystallographic analysis shows that the most significant strengthening effect of the X-phase originates from its coherent orientation relationship with the α-Mg matrix and the development of deformation-induced kink bands. Meanwhile, fine W-phase particles embedded within the X-phase further enhance alloy performance by suppressing X-phase deformation, revealing pronounced synergistic strengthening between the two phases. Notably, although both the I-phase and W-phase act as crack initiation sites during deformation, their coexistence triggers a competitive fracture mechanism: the I-phase preferentially fractures to preserve the structural integrity of the W-phase, effectively mitigating crack propagation. These dynamic interactions of second phases during plastic deformation—synergistic strengthening and competitive fracture—provide a novel strategy and insights for designing high-performance Mg–RE–Zn alloys. Full article

This study systematically investigated the effects of biologically relevant microalloying elements—calcium (Ca), strontium (Sr), manganese (Mn), and zirconium (Zr)—on the electrochemical behavior of Mg-Y-Zn alloys containing long-period stacking ordered (LPSO) phases. The alloys were prepared by casting and characterized using X-ray diffraction (XRD), optical microscopy (OM), and scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS). Electrochemical properties were assessed through potentiodynamic polarization in Hank’s solution, and corrosion rates were determined by hydrogen evolution and weight loss methods. Microalloying significantly enhanced the corrosion resistance of the base Mg-Y-Zn alloy, with corrosion rates decreasing from 2.67 mm/year (unalloyed) to 1.65 mm/year (Ca), 1.36 mm/year (Sr), 1.18 mm/year (Zr), and 1.02 mm/year (Mn). Ca and Sr additions introduced Mg₂Ca and Mg₁₇Sr₂, while Mn and Zr refined the existing LPSO structure without new phases. Sr refined the LPSO phase and formed a uniformly distributed Mg₁₇Sr₂ network, promoting uniform corrosion and suppressing deep localized attacks. Ca-induced Mg₂Ca acted as a temporary sacrificial phase, with corrosion eventually propagating along LPSO interfaces. The Mn-containing alloy exhibited the lowest corrosion rate; this is attributed to the suppression of both anodic and cathodic reaction kinetics and the formation of a stable protective surface film. Zr improved general corrosion resistance but increased susceptibility to localized attacks due to dislocation-rich zones. These findings elucidate the corrosion mechanisms in LPSO-containing Mg alloys and offer an effective strategy to enhance the electrochemical stability of biodegradable Mg-based implants. Full article

A method for generally predicting interface chemical bonding at the metal–oxide interface with the interface reaction considered is reported. So far, the interface between pure metal or alloy and 11 oxides—MgO, Al₂O₃, SiO₂, Cr₂O₃, ZnO, Ga₂O₃, Y₂O₃, ZrO₂, CdO, La₂O₃, and HfO₂—without considering the interface reaction, has been discussed and implemented in the free web-based software product InterChemBond (v2022). Now, the number of oxides available for prediction is 83 in total. Among them, 29 oxides are in one stable valence, and the others are multi-valence. The newly developed prediction method considering the interface reaction is additionally implemented in InterChemBond. The principles and formula for predicting interface bonding while considering interface reactions are provided as well as some screenshots of the software. Full article

The microstructural, mechanical and corrosion properties of low-alloyed Mg-Zn-Ca alloys with different Zn/Ca atomic ratios were investigated. The results show that the microstructure of the extruded Mg-1Zn-0.3Ca (ZX1.0) alloy mainly consists of α-Mg and Ca₂Mg₆Zn₃ phases and a small amount of Mg₂Ca phase. In contrast, the Mg₂Ca phase disappears in the alloys Mg-1.4Zn-0.3Ca (ZX1.4), Mg-1.8Zn-0.3Ca (ZX1.8) and Mg-2.3Zn-0.5Ca (ZX2.3). The Ca₂Mg₆Zn₃ phases are mainly distributed along the extrusion direction, showing irregular particle shapes and banded particles. Meanwhile, the grain size of the extruded Mg-Zn-Ca alloy is reduced gradually with the increase of the Zn and Ca contents, decreasing from 1.87 μm in ZX1.0 to 1.28 μm in ZX2.3 alloy. Fine grain strengthening and second-phase strengthening increase the yield strength and ultimate tensile strength of the alloy. In addition, when the Zn/Ca ratio is the same, the total elemental content dominates the effect on alloy properties. When increasing the Zn/Ca ratio, the potential difference between Ca₂Mg₆Zn₃ and the Mg matrix increased, resulting in an increase in galvanic corrosion. The negative effect of the volume fraction of the second phase and the positive effect of the fine grain size determine the corrosion performance together. Therefore, ZX1.8 exhibits the best corrosion resistance, of 0.14 mm/y. Full article

By adjusting the Y/Zn (wt.%) ratio while maintaining the total mass of Y and Zn unchanged, the evolution of the microstructure and mechanical properties of Mg-Y-Zn alloy castings with different phase types was investigated. The results indicated that the studied alloy exhibited a typical $\mathsf{\alpha }$-Mg dendritic structure, which contained intermetallic compounds such as phase I, phase I + W, phase W + LPSO, and phase LPSO. The phase evolution process of Mg-Y-Zn alloys was analyzed in conjunction with microstructural observations. The strengthening effects on the mechanical properties of five alloys with different compositions revealed that as the Y/Zn ratio increased, secondary phase strengthening gradually became the primary strengthening mechanism, with the contribution order being W + LPSO > LPSO > I + W > I. Full article

The effects of extrusion temperatures on the microstructure, mechanical properties, and corrosion performance of biomedical Mg-1Zn-0.4Ca-1MgO composites were systematically investigated. The results indicated that lower extrusion temperatures notably refined the grain size and promoted the formation of numerous nano-scaled secondary phase particles. The grain sizes were 0.8 μm, 1.7 μm, and 3.4 μm for the materials extruded at 280 °C, 310 °C, and 330 °C, which were named ET280, ET310, and ET330. The finest grain size and abundant precipitates enhanced the mechanical properties of the composite with a microhardness of 86.9 HV, a yield strength of 305 MPa, and a fracture elongation of 15.2%. Moreover, the ET280 alloy with ultra-fine grains exhibited the optimal corrosion resistance among these three composites, and its annual corrosion after immersion in Hank’s solution for 14 days was only 0.17 mm/y. The excellent performance in vitro immersion was mainly attributed to the formation of the uniformly dense Ca-P layer on its surface and the contiguous compact Mg(OH)₂ layer, which could effectively weaken the contact between the corrosive solution and the Mg matrix. Full article

The body-centered cubic (BCC)-structured magnesium–lithium (Mg-Li) alloy is the lightest metal material, but its mechanical properties are poor, especially its strength. In this study, the effect of adding rare earth Y on the microstructure and mechanical properties of as-cast BCC Mg-11Li-6Zn-xY (x = 0, 0.5, 1.2, and 2, in wt.%) alloys was investigated. The results revealed that massive amounts of nano-scale θ (MgLiZn) and/or θ’ (MgLi₂Zn) precipitated inside the grains, and some θ phases precipitated at the grain boundaries in the Mg-11Li-6Zn alloy. With the addition of Y, W phases formed at the grain boundary, their content gradually increased with the Y concentration, and the grain size decreased simultaneously. The Mg-11Li-6Zn-0.5Y alloy exhibited higher ultimate tensile strength (190 MPa) and elongation (27%) at room temperature than those (170 MPa and 22%) of the Mg-11Li-6Zn alloy, presenting improvements of 11.8% and 22.7% in strength and ductility, respectively. The improvements in the mechanical properties of the Mg-11Li-6Zn alloy achieved by adding less Y could be attributed to the formation of moderate W phases and a reduction in grain size. However, once the addition of Y became excessive, the mechanical properties of the Mg-11Li-6Zn-1.2Y alloy were reduced due to the formation of too many reticular W phases. In addition, the Mg-11Li-6Zn-2Y alloy containing the highest Y content had the lowest ultimate tensile strength, 163 MPa, and highest ductility, 38%, due to the combined effect of the most reticular W phases and the smallest grains. Furthermore, the fracture morphology of the Mg-11Li-6Zn alloy displayed apparent necking, which became insignificant after the addition of Y, indicating that this addition could improve its uniform plastic deformation ability. Full article

This study systematically investigated the effects of the addition of the rare earth element yttrium (Y) on the microstructural evolution, mechanical properties, and corrosion behavior of as-extruded Al-5.6Zn-2.5Mg-1.6Cu-0.20Cr (wt.%) alloy through comprehensive characterization techniques, including X-ray diffraction (XRD), tensile testing, corrosion analysis, and electron microscopy. Microstructural characterization demonstrated that the incorporation of yttrium resulted in significant refinement of secondary phase particles within the as-extruded alloy matrix. Moreover, quantitative analysis revealed a substantial increase in low-angle grain boundary (LAGB) density, dislocation density, and the formation of subgrain structures. Notably, the volume fraction of η′ strengthening precipitates showed a marked increase, accompanied by a corresponding reduction in the width of precipitate-free zones (PFZs) along grain boundaries. Following the T74 aging treatment, the alloy with 0.1 wt.% yttrium addition exhibited a remarkable improvement in intergranular corrosion resistance, with the maximum corrosion depth reduced to 107.8 μm. However, it should be noted that the exfoliation corrosion resistance exhibited an inverse correlation with increasing yttrium content, suggesting a concentration-dependent behavior in corrosion performance. Full article

Traditional magnesium structural materials are used widely due to their light weight; however, their corrosion resistance is poor. In order to address this problem and improve the strength simultaneously, SiCp-, SiCnp-, and SiCnw-reinforced Mg-2Zn-0.1Y (wt. %, MZY alloy) matrix composites (SiC/MZY composites) with the same contents (0.3 wt. %) were prepared and extruded at low temperature in this paper. The effects of SiC morphology on the microstructure, mechanical properties and corrosion resistance of MZY alloy were studied. The results show that the grain size can be refined by adding SiC reinforcement. Compared with the unreinforced MZY alloy, the strengths of the SiC/MZY composites were all improved, with a yield strength of more than 440 MPa and an ultimate tensile strength of more than 450 MPa. However, only the corrosion rate of the composites reinforced by submicron SiCp was improved significantly. The hydrogen evolution corrosion rate (P_H) was reduced by 81% relative to the MZY alloy. This can be attributed to the decreased galvanic corrosion pairs, as well as the decreased potential difference between the second phase and the matrix in the SiCp/MZY composite. Additionally, a compact product film on the surface of the SiCp/MZY composite can also protect the matrix. The materials prepared in this study showed excellent strength and high corrosion resistance at relatively low cost, providing valuable insights and design ideas for the development and application of those materials in marine and offshore engineering applications. Full article

This study investigated the influence of plasma electrolytic oxidation (PEO) preparation time on the degradation resistance of Mg-1Zn (Z1) and Mg-1Zn-0.4Ca (ZX10) alloys, with comparisons to pure Mg and commercial Mg-4Y-3RE-0.4Zr (WE43). PEO layers were formed with varying preparation times (5, 10, and 15 min) and analyzed for microstructure, morphology, and corrosion resistance. The results indicated that PEO layers with a 10 min preparation time had the most homogeneous structure and optimal corrosion resistance. Prolonged PEO preparation times increased pore density, crack formation, and layer thickness while also promoting layer degradation during extended immersion in 0.9% NaCl corrosive media. The dissolution of phosphates from PEO layers contributes to the formation of a protective corrosion layer, enhancing long-term resistance. These findings demonstrate that low-alloyed, biocompatible Mg-Zn(-Ca) alloys can achieve corrosion resistance comparable to high-performance WE43 alloys through appropriate surface treatment. Full article

Grain refinement is of very important significance for improving the microstructure and mechanical properties of Mg alloys. This work investigated how the addition of various amounts of Y element affected the microstructure and mechanical properties of Mg-9Al-1Zn alloy. It was found that the grain size of Mg-9Al-1Zn alloy decreases as Y element content increases. When 1.2 wt.% Y element content was added, the grain size of Mg-9Al-1Zn alloy could be reduced from 334.2 μm to 134.6 μm, and grain refinement efficiency of 60% was achieved. HRTEM analysis demonstrated a good orientation relationship between the Al₂Y phase and the Mg interface, and therefore, it was determined that the Al₂Y phase can be used as a heterogeneous nucleation site for α-Mg grains, which promotes the grain refinement of α-Mg grain. Furthermore, the addition of Y element can also significantly refine the eutectic Mg₁₇Al₁₂ phase of the Mg-9Al-1Zn alloy. In this way, the mechanical properties of the Mg-9Al-1Zn alloy are significantly enhanced. It was found that the YS and UTS of the Mg-9Al-1Zn alloy reached 87 MPa and 154 MPa with the addition of 0.9 wt.% of Y element—24% and 43% higher than the Mg-9Al-1Zn alloy. Full article

This study presents a comparative analysis of the influence of Ce-Gd and Gd-Y additions on the microstructural evolution, mechanical properties, and electrochemical behavior of extruded Mg-3Zn-Mn-Ca alloy rods. Despite the frequent incorporation of Gd, Y, and Ce as alloying elements in magnesium alloys, the systematic examination of their combined effects on Mg-Zn alloys has been limited. Our findings reveal that both Gd-Ce and Gd-Y additions significantly enhance the mechanical properties of Mg-3Zn-Mn-Ca alloy, although through differing mechanisms. Specifically, the Mg-3Zn-1Mn-0.5Ca-1Gd-0.5Ce(ZMXE3101(GdCe)) alloy exhibited a yield strength of 304.5 MPa and an elongation of 15%, achieved through dynamic recrystallization and enhanced basal texture. The grain refinement and texture strengthening resulting from the coarse second-phase particles formed by Ce-Gd played a significant role in increasing the yield strength. In contrast, the Mg-3Zn-1Mn-0.5Ca-1Gd-0.5Y (ZMXE3101(GdY)) alloy demonstrated a yield strength of 305 MPa and an elongation of 20%. The finer grains and elongated unrecrystallized grains formed by Gd-Y contributed to the elevation in yield strength. While the ductility of this alloy was slightly lower than that of Mg-3Zn-Mn-Ca without rare earth additions, it still exhibited commendable overall mechanical properties. The electrochemical test results indicate that the addition of both Gd-Ce and Gd-Y enhances the corrosion current density of Mg-3Zn-Mn-Ca alloy, attributable to the generation of numerous rare earth phase particles that function as cathodes. Compared to the ZMXE3101(GdY) alloy, ZMXE3101(GdCe) exhibits a higher equilibrium potential and significantly lower corrosion current density. This is due to the formation of a protective film during the corrosion process by Gd-Ce. Full article

Due to limited slip systems activated at room temperature, the plastic deformation of Mg and its alloys without any preheating of initial billets is significantly limited. To overcome those issues, new methods of severe plastic deformation are discovered and developed. One such example is extrusion with an oscillating die, called KoBo. This method, due to the oscillations of reversible die located at the end of extruded, introduces material into the plastic flow, and thus, enables deformation without preheating of the initial billets of metals that are hard to deform. Such solution is important from an industrial point of view and may lead to serious savings and reduction in carbon dioxide emission to the atmosphere. Therefore, this paper focuses on the possibility of KoBo extrusion of hcp-structured Mg alloys with different chemical compositions and includes comparison of their corrosion resistance using short-term electrochemical tests. In order to have a broad view of the problem presented, we compared the electrochemical behavior of the following groups of Mg materials: pure Mg, Mg-Al-Zn, Mg-Li, and Mg-Y-RE. It was stated that the KoBo method performed at room temperature improves the corrosion resistance of pure Mg when compared to the initial billet and the alloys which belong to the Mg-Al-Zn, Mg-Li, and Mg-Y-RE series. The presented study shows that different corrosion trends are observed for traditionally deformed alloys, and they significantly vary from nascent developments, such as KoBo extrusion. Therefore, it is crucial to widely study those methods because it may be a path leading to long-lasting solution to the formability limitations of Mg-based metallic systems. Full article

Mg-6Zn-0.5Mn as a medical magnesium alloy has good biomechanical properties and corrosion resistance, but as a fracture internal-fixation material, its strength, toughness, and corrosion resistance still need to be improved. In this paper, the element Sr, having good biocompatibility, is used as an alloy element. The effects of different Sr contents (0 wt.%, 0.3 wt.%, 0.6 wt.%, 0.9 wt.%, and 1.2 wt.%) on the microstructure, strength, toughness, and corrosion resistance of rolled Mg-6Zn-0.5Mn alloy were studied. The results are as follows. Sr can influence the recrystallization process. When the Sr content is 0.3 wt.% and 0.6 wt.%, the alloy matrix exhibits both non-recrystallized regions and fine recrystallized regions. When the Sr content reaches 0.9 wt.%, the non-recrystallized region decreases significantly, and the fine recrystallized grains develop into equiaxed grains. With the increase of Sr content, the elongation of the alloy decreases. At a content of 0.9 wt.%, the corrosion resistance reaches its optimum value, with an average corrosion rate of 0.75828 mm/y. Full article