Search Results (8)

The application of biodegradable alloys in orthopedic implants has gained widespread attention globally. Magnesium alloys with controllable degradation rate and suitable mechanical properties have been regarded as potential orthopedic implant material. In this paper, a Mg-1Zn-xSn (x = 0, 1.0, 1.5, 2.0 wt.%) ternary alloy was designed and its performance was investigated. Compared with the Mg-1Zn alloy, the Mg-1Zn-xSn alloys showed enhanced mechanical properties and in vitro degradation performance. Above all, the extruded Mg-1Zn-1.0Sn alloy exhibited an extremely low corrosion rate of 0.12 mm/y with a low hydrogen release of 0.021 mL/cm²/day, which can be attributed to the hydrogen release suppression effect caused by Sn and SnO₂ formation in the surface of the alloy. The cytotoxicity of the Mg-1Zn-1.0Sn alloy was evaluated by the cell counting kit-8 (CCK-8) method, the results of which show that its cytotoxicity grade is zero, and the MC3T3-E1 cells spread well on the alloy surface. The findings in this paper demonstrated that Mg-1Zn-1.0Sn is a potential candidate for biodegradable material in the orthopedic implant field. Full article

Magnesium alloys are widely employed in various applications due to their high strength-to-weight ratio and superior mechanical properties as compared to unalloyed Magnesium. Alloying is considered an important way to enhance the strength of the metal matrix composite but it significantly influences the damping property of pure magnesium, while controlling the rate of corrosion for Mg-based material remains critical in the biological environment. Therefore, it is essential to reinforce the magnesium alloy with a suitable alloying element that improves the mechanical characteristics and resistance to corrosion of Mg-based material. Biocompatibility, biodegradability, lower stress shielding effect, bio-activeness, and non-toxicity are the important parameters for biomedical applications other than mechanical and corrosion properties. The development of various surface modifications is also considered a suitable approach to control the degradation rate of Mg-based materials, making lightweight Mg-based materials highly suitable for biomedical implants. This review article discusses the various binary and ternary Mg alloys, which are mostly composed of Al, Ca, Zn, Mn, and rare earth (RE) elements as well as various non-toxic elements which are Si, Bi, Ag, Ca, Zr, Zn, Mn, Sr, Li, Sn, etc. The effects of these alloying elements on the microstructure, the mechanical characteristics, and the corrosion properties of Mg-based materials were analyzed. The mechanical and corrosion behavior of Mg-based materials depends upon the percentage of elements and the number of alloying elements used in Mg. The outcomes suggested that ZEK100, WE43, and EW62 (Mg-6% Nd-2% Y-0.5% Zr) alloys are effectively used for biomedical applications, having preferable biodegradable, biocompatible, bioactive implant materials with a lower corrosion rate. Full article

At present, magnesium master alloys with such rare earth metals (REM) as yttrium are used in the production of alloys of magnesium and aluminum. These alloys especially the system Mg-6Zn-1Y-0,5Zr are commonly used in the aircraft and automotive industries. The article is devoted to the exploration of the synthesis process features for ternary magnesium master alloys with yttrium and zinc. The authors used X-ray fluorescence analysis (XRF), differential thermal analysis (DTA), and X-ray spectral analysis (XRD). Optical microscopy was used to conduct microstructural studies. The thermal effects that occur during metallothermic reactions of yttrium reduction from the YF₃-NaCl-KCl-CaCl₂ salt mixture with a melt of magnesium and zinc were investigated, and the temperatures of these effects were determined. It has been confirmed that the metallothermic reaction of yttrium reduction proceeds from the precursors of the composition: Na_1.5Y_2.5F₉, NaYF₄, Na₅Y₉F₃₂, and KY₇F₂₂, and starts at a temperature of 471 °C. The results of experimental studies of the process of metallothermic reduction of yttrium from the salt mixture YF₃-NaCl-KCl-CaCl₂ are presented in detail. These experiments were carried out in a pit furnace at temperatures ranging from 650 to 700 °C, and it was found that, at a synthesis temperature of 700 °C, the yttrium yield is up to 99.1–99.8%. The paper establishes rational technological regimes for the synthesis (temperature 700 °C, exposure for 25 min, the ratio of chlorides to yttrium fluoride 6:1, periodic stirring of the molten metal) at which the yttrium yield reaches up to 99.8%. The structure of the master alloy samples obtained during the experiments was studied. That structure can be distinguished by a uniform distribution of ternary intermetallic compounds (Mg₃YZn₆) in the bulk of the double magnesium–zinc eutectic. Studies have been carried out on testing the obtained ternary master alloy as an alloying material in the production of alloys of the Mg-6Zn-1Y-0.5Zr system, while the digestibility of yttrium ranged from 91 to 95%. Full article

Magnesium alloys are a strong candidate for various applications in automobile and aerospace industries due to their low density and specific strength. Micro-alloying magnesium with zinc, yttrium, and cerium enhances mechanical properties of magnesium through grain refinement and precipitation hardening. In this work, a critical review of magnesium-based binary systems including Mg-Zn, Mg-Y, Mg-Ce, Zn-Y, and Zn-Ce is presented. Based on the CALPHAD approach and first-principles calculations, thermodynamic modeling of Mg-Zn-Y and Mg-Zn-Ce ternary phase diagrams have been summarized. The influence of micro-alloying (yttrium and cerium) on the mechanical properties of magnesium is discussed. A comparison between mechanical properties of magnesium commercial alloys and magnesium–zinc–{yttrium and cerium} have been summarized in tables. Full article

As-cast Mg₉₇Zn₁Y₂ alloy consists of α-Mg matrix and 18R-type long-period stacking-ordered (LPSO) structures. We observed that the alloy undergoes a phase transformation to D0₃ superlattices and α-Mg matrix due to high-pressure high-temperature (HPHT) annealing at 3 GPa and above 773 K. Further, the alloy recovered after HPHT annealing, consisting of the α-Mg matrix and D0₃ superlattices, transformed into 18R-type LPSO structures during further annealing at ambient pressure. An fcc structure with a lattice parameter of 1.42 nm, which was twice that of D0₃, emerged in both the collapse process of the 18R-type LPSO structure under high-pressure, and the formation process of the 18R-type LPSO structure at ambient pressure. This fcc phase was an intermediate structure between 18R-type LPSO and D0₃. From the electron diffraction results, it is considered that 18R-type LPSO is continuously present with 2H including stacking faults, which almost corresponded with previous studies. Full article

Zinc biodegradable alloys attracted an increased interest in the last few years in the medical field among Mg and Fe-based materials. Knowing that the Mg element has a strengthening influence on Zn alloys, we analyze the effect of the third element, namely, Y with expected results in mechanical properties improvement. Ternary ZnMgY samples were obtained through induction melting in Argon atmosphere from high purity (Zn, Mg, and Y) materials and MgY (70/30 wt%) master alloys with different percentages of Y and keeping the same percentage of Mg (3 wt%). The corrosion resistance and microhardness of ZnMgY alloys were compared with those of pure Zn and ZnMg binary alloy. Materials were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), linear and cyclic potentiometry, and immersion tests. All samples present generalized corrosion after immersion and electro-corrosion experiments in Dulbecco solution. The experimental results show an increase in microhardness and indentation Young Modulus following the addition of Y. The formation of YZn12 intermetallic phase elements with a more noble potential than pure Zinc is established. A correlation is obtained between the appearance of new Y phases and aggressive galvanic corrosion. Full article

The Mg-Nd-Zn isothermal section at 300 °C was established in the full composition range using diffusion couples and equilibrated key alloys. Microstructural characterization was carried out using WDS, XRD, and metallographic methods. The homogeneity ranges of the binary and ternary compounds were determined by WDS analysis. Six ternary compounds were observed in the Mg-Nd-Zn system at 300 °C. These are: τ₁ (Nd₅Mg_21+xZn_45−x; 0 ≤ x ≤ 4), τ₂ (Nd₅Mg_3+yZn_25−y; 0 ≤ y ≤ 1), τ₃ (NdMg_1+zZn_2−z; 0 ≤ z ≤ 0.44), τ₄ (Mg₄₀Nd₅Zn₅₅), τ₅ (Mg_22–23.5Nd_15.5–17.5Zn_59.1–61.8), and τ₆ (Nd₂(Mg,Zn)₂₃). τ₅ was found to have a homogeneity range of 22.0–23.5 atom % Mg, 15.5–17.6 atom % Nd and 59.1–61.8 atom % Zn and τ₆ was found to have 54.1–61.3 atom % Mg at a constant Nd of 8.0 atom %. The ternary solubility of Zn in Mg-Nd compounds was found to increase with the decrease in Mg concentration. Accordingly, (Mg₄₁Nd₅) was found to have an extended solubility of 3.1 atom % Zn, whereas (Mg₃Nd) was found to have 30.0 atom % Zn. MgNd was found to have a complete substitution of Mg by Zn. The maximum solid solubility of Zn in α-Mg was measured as 4.8 atom % Zn. Full article

The isothermal section of the Ce-Mg-Zn system at 300 °C was experimentally established in the full composition range via diffusion multiple/couples and key alloys. Annealed key alloys were used to confirm the phase equilibria obtained by diffusion multiple/couples and to determine the solid solubility ranges. Spot analysis was carried out, using wavelength dispersive X-ray spectroscopy (WDS), to identify the composition of the observed phases. The composition profiles were obtained using WDS line-scans across the diffusion zones. X-ray diffraction (XRD) was performed to identify the phases in the annealed alloys and to confirm the WDS results. Eight ternary compounds, in the Ce-Mg-Zn isothermal section at 300 °C, were observed from 45–80 at.% Zn. These are: τ₁ (Ce₆Mg₃Zn₁₉), τ₂ (CeMg₂₉Zn₂₅), τ₃ (Ce₂Mg₃Zn₃), τ₄ (CeMg₃Zn₅), τ₅ (CeMg₇Zn₁₂), τ₆ (CeMg_2.3−xZn_12.8+x; 0 ≤ x ≤ 1.1), τ₇ (CeMgZn₄) and τ₈ (Ce(Mg_1−yZn_y)₁₁; 0.096 ≤ y ≤ 0.43). The ternary solubility of Zn in the Ce-Mg compounds was found to increase with a decrease in Mg concentration. Accordingly, the ternary solid solubility of Zn in CeMg₁₂ and CeMg₃ was measured as 5.6 and 28.4 at.% Zn, respectively. Furthermore, the CeMg and CeZn showed a complete solid solubility. The complete solubility was confirmed by a diffusion couple made from alloys containing CeMg and CeZn compounds. Full article