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Summary of Zn-rich ends of binary Zn diagrams: (a) Eutectic phase diagram. (b) Peritectic phase diagram with solid dissoluble element X. (c) Peritectic phase diagram with solid indissoluble X and a stoichiometric intermetallic compound γ. (d) Peritectic phase diagram with solid indissoluble X and a non-stoichiometric intermetallic compound α.
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Alloying combined with plastic deformation processing is widely used to improve mechanical properties of pure Zn. As-cast Zn and its alloys are brittle. Beside plastic deformation processing, no effective method has yet been found to eliminate the brittleness and even endow room temperature super-ductility. Second phase, induced by alloying, not on...
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... The size can be roughly estimated in as-cast state by the reaction during solidification in the Zn-rich end of a phase diagram. Generally speaking, second phase formed due to eutectic reaction is much finer than that formed due to peritectic reaction. The possible alloying elements that can have an eutectic reaction with Zn are summarized in Fig. 2a. Some of them form an eutectic structure of Zn and an intermetallic compound, including Mg, Mn, Li and Cr. The others form an eutectic structure of Zn and a simple substance, including Sn, Ge, Al and Bi. Much more elements have a peritectic reaction with ...
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... with solid solubilities in Zn are summarized in Fig. 2b, including Cu, Au and Ag. The others without solid solubility in Zn are summarized in Fig. 2c with a stoichiometric γ phase and in Fig. 2d with a nonstoichiometric α phase. When the reaction of L→L+α or L→L+γ takes place, the primary solidification phase (i.e., α or γ phase) is often coarse and dendrite-like intermetallic compound under ...
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... with solid solubilities in Zn are summarized in Fig. 2b, including Cu, Au and Ag. The others without solid solubility in Zn are summarized in Fig. 2c with a stoichiometric γ phase and in Fig. 2d with a nonstoichiometric α phase. When the reaction of L→L+α or L→L+γ takes place, the primary solidification phase (i.e., α or γ phase) is often coarse and dendrite-like intermetallic compound under conditions of conventional casting [14][15][16][17]. For the elements without solid ...
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... with solid solubilities in Zn are summarized in Fig. 2b, including Cu, Au and Ag. The others without solid solubility in Zn are summarized in Fig. 2c with a stoichiometric γ phase and in Fig. 2d with a nonstoichiometric α phase. When the reaction of L→L+α or L→L+γ takes place, the primary solidification phase (i.e., α or γ phase) is often coarse and dendrite-like intermetallic compound under conditions of conventional casting [14][15][16][17]. For the elements without solid solubility in Zn, such as Ca and Fe, the sizes of ...
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Citations
... The second phase plays a relevant role in improving the properties of zinc-based biomedical alloys. Shi et al. [1] found, considering 23 possible non-toxic alloying elements, that Ag and Cu are among the five most promising elements for improving the mechanical properties of zinc-based biodegradable alloys. This selection occurs given the high solubility in zinc of Ag and Cu, which produces solid solution hardening and precipitation hardening. ...
Zn-Ag-Cu alloys have recently attracted attention as alloy candidates for biomedical applications, but, to date, they have not achieved the required mechanical properties. To improve the mechanical properties of Zn-Ag-Cu-base alloys, in this work, the effects of the presence of increasing amounts of Ag and Cu as alloying elements on the properties of four 0.05% Mg-micro-alloyed Zn-Ag-Cu base alloys are explored. The alloys were manufactured in an electric furnace with a protective atmosphere using increasing amounts of Ag and Cu as alloying agents, and were cast in a metallic mold. The samples obtained were thermomechanically processed by hot extrusion. Three of the four alloys under study presented increasing amounts of the second phase (Ag, Cu)Zn4, high mechanical properties, a microstructure and mechanical behavior characteristic of heteromaterials with a heterogeneous lamella-structure, and met the requirements of the mechanical properties, corrosion rate, antibacterial properties against S. aureus, and the cytotoxicity required for biomedical applications. It seems possible to tune the properties of the ZnAgCu-0.05% Mg alloys by changing the Ag and Cu contents.
... Fig. 1 shows the structure of the initial cast material after a homogenizing annealing. Presumably, the phases Zn, Mg 2 Zn 11 and FeZn 13 are present in the alloy, which is in agreement with the phase diagram of Zn-Mg [21] and Zn-Fe [22]. According to enegy-dispersive X-ray spectroscopy (EDS), the Mg 2 Zn 11 phase is located at the boundaries of the Zn phase ( Fig. 1, d). ...
Bioresorbable zinc alloys are ever more often regarded as promising materials for medical implants and vascular stents since they have a lower corrosion rate in a physiological environment in comparison with magnesium alloys. At the same time, products made of zinc alloys must have a controlled corrosion rate to provide the required time for the recovery of the body. It is known that in determining the corrosion rate, an important role is played by the choice of the test method and its parameters (corrosive environment, environment temperature, the sample's exposure time in the corrosive environment). In the present study, the gravimetric method was used, based on a precise measurement of the substance mass prior to and after testing. The surface of the samples subjected to corrosion tests was investigated using scanning electron microscopy and energy-dispersive analysis. The aim of the present study is to reveal the effect of the samples' exposure time in a corrosive environment, as well as the frequency of surface cleaning, on the corrosion resistance of the Zn-1Fe-1Mg biodegradable zinc alloy. It is shown that under the same test conditions but different frequencies of surface cleaning, the corrosion rates may differ by a factor of 3.8.
... Secondly, the integration of Mg and Sr with Zn in the alloy matrix formed secondary phases such as Mg 2 Zn 11 , MgZn 2 , and SrZn 13 . These secondary phases contributed to solid solution strengthening [12]. Vojtech et al. [36] found that Mg was shown to substantially increase the tensile strength and elongation of Zn alloys. ...
... Mg, which is essential for normal metabolism, can enhance cell activity, promote adhesion and proliferation, and aid in the healing of bone tissue at appropriate levels [11]. Sr, a bone-supporting element, has been shown to promote cell differentiation and new bone formation, although the low concentration of Sr 2+ results in a minimal effect on cell activity [12]. Hernandez et al. [57] observed that the Zn alloy exhibits significant cytotoxic effects in vitro, but the toxicity is markedly reduced in vivo. ...
In recent years, the use of zinc (Zn) alloys as degradable metal materials has attracted considerable attention in the field of biomedical bone implant materials. This study investigates the fabrication of porous scaffolds using a Zn-1Mg-0.1Sr alloy through a three-dimensional (3D) printing technique, selective laser melting (SLM). The results showed that the porous Zn-1Mg-0.1Sr alloy scaffold featured a microporous structure and exhibited a compressive strength (CS) of 33.71 ± 2.51 MPa, a yield strength (YS) of 27.88 ± 1.58 MPa, and an elastic modulus (E) of 2.3 ± 0.8 GPa. During the immersion experiments, the immersion solution showed a concentration of 2.14 ± 0.82 mg/L for Zn2+ and 0.34 ± 0.14 mg/L for Sr2+, with an average pH of 7.61 ± 0.09. The porous Zn-1Mg-0.1Sr alloy demonstrated a weight loss of 12.82 ± 0.55% and a corrosion degradation rate of 0.36 ± 0.01 mm/year in 14 days. The Cell Counting Kit-8 (CCK-8) assay was used to check the viability of the cells. The results showed that the 10% and 20% extracts significantly increased the activity of osteoblast precursor cells (MC3T3-E1), with a cytotoxicity grade of 0, which indicates safety and non-toxicity. In summary, the porous Zn-1Mg-0.1Sr alloy scaffold exhibits outstanding mechanical properties, an appropriate degradation rate, and favorable biosafety, making it an ideal candidate for degradable metal bone implants.
... Therefore, the diluted Zn-5Nd extract has higher cytocompatibility than the pure Zn extract. In addition, the MG-63 cells had a higher cytotoxicity in the diluted extracts than MC3T3-E1, mainly because MG-63 cells are more tolerant to Zn ions than MC3T3-E1 cells [77]. ...
... In addition, the hardness value of the alloy can increase due to the formation of intermetallic phases previously discussed during XRD testing. MnZn13 is an intermetallic phase with a hardness value of 168.2 HV, while the hardness value of Zn is only around 31.8 HV [15]. Along with the formation of the MnZn13 intermetallic phase which is more dominant in Zn-Mn alloy, it can increase the hardness value of the alloy. ...
Zn-based biodegradable implants were still relatively new, and much development was needed. This study added varying amounts of Mn to Zn alloys and analyzed their effect on corrosion rate. Corrosion testing was conducted electrochemically with a polarization test. The alloys were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of the additional Mn content was also observed through a hardness test. Zn-25Mn alloy had the lowest corrosion rate. The alloy, with the addition of certain levels of Mn, experienced the formation of the intermetallic phase MnZn13, which improved the mechanical properties and corrosion rate. This research provided insights into the biocompatibility of a biodegradable implant through in vivo and in vitro testing, allowing for further development of its results.
... In the diluted extract, the cell viability of MG-63 cells was higher compared to that of MC3T3-E1 cells, mainly due to the disparity in metal ion tolerance and pH sensitivity between the two cell types. Shi et al. [96] found that MG-63 cells had higher tolerance to Zn ions than MC3T3-E1 cells. ...
... Although the strength of pure Zn is still insufficient, its high elongation (up to 40%) allows for further thermal deformation processing. As a result, the mechanical properties of Zn alloys can currently be improved through alloying, heat deformation, powder metallurgy, additive manufacturing, and other methods [22,39,40]. Furthermore, considering the implant's location and function, a more detailed approach to specifying the tensile strength and elongation requirements for load-bearing implants in the context of internal fixation is warranted. ...
Compared to biodegradable Mg-based and Fe-based alloys, Zn-based alloys offer distinct advantages as ortho-pedic internal fixation implants due to their tunable mechanical strength, moderate corrosion rate, pleasant cytocompatibility, dose-dependent osteoinductivity, intrinsic bacteriostatic activity. Therefore, recent attention has been paid on the design, fabrication, and clinical translation of Zn-based alloys. The purpose of this research was to briefly discuss the feasibility, challenges, and future prospects of utilizing biodegradable Zn-based alloys as orthopedic internal fixation implants.
... Therefore, the cytocompatibility is gradually enhanced with the dilution of the extract concentration. In addition, the cytocompatibility of MG 63 cells was higher than that of MC3T3-E1 cells at the diluted extracts, mainly because the tolerance of MG 63 cells towards Zn ion was higher than that of MC3T3-E1 cells, which was consistent with our previous study [32] and Shi et al. [72]. ...
... Therefore, in the present work we used Zn/Mg as a bimetal system and employed ARB to produce lamellar Zn matrix composites. The reasons for choosing Mg as the reinforcement in the lamellar Zn matrix composites are that, firstly, Mg has good biocompatibility and degradability and, secondly, Mg has limited solid solubility in the Zn lattice and its maximum solid solubility at 364 °C is only 0.1% [46] , which ensures the formation of interfaces between Zn and Mg layers during rolling of Zn/Mg sandwiched sheets. On the other hand, in general for a bimetal multilayer system, the actual deformation of the two metals is not uniform during the ARB process due to their different flow stresses. ...
... Currently, the enhancement of Zn's mechanical attributes has been improved through alloying and plastic deformation, driven by the demand for biodegradable metals [9]. Developed Zn alloys exhibit high strength and elongation. ...
The equal channel angular pressing (ECAP) process was used to develop a Zn-1Mg alloy with a tensile strength of 440 MPa and uniform elongation of 11%. The uniform elongation of the ECAPed Zn-1Mg alloy is higher than that of other Zn alloys with strengths over 400 MPa. The microstructure of the ECAPed Zn-1Mg alloy evolved through dynamic recrystallization (DRX), resulting in a refined grain structure. Additionally, the lamellar eutectic structure was fragmented into sub-micrometer particles (~0.9 μm). The high strength of the Zn-1Mg alloy is due to both grain boundary strengthening and second phase strengthening. The high uniform elongation is attributed to the presence of plate-shaped precipitates with a high density of 1014m-2. The in-vitro results indicate that ECAPed Zn-1Mg alloy has high cell viability (>100%). Meanwhile, the Zn-1Mg alloy processed by ECAP exhibited better ALP activity and alizarin red results than pure Zn. These results demonstrate that Zn-1Mg alloy is beneficial to the proliferation and differentiation of osteoblasts, and also promote blood vascular formation. The good osteogenic and angiogenic properties of the alloy are attributed to the release of Mg2+ and Zn2+ during the degradation process, which play a critical role in biochemical reactions in the human body. Therefore, the high uniform elongation and good biological properties make Zn-Mg based alloys a promising material for expanding applications in the orthopedic field.
