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Iron–selenium (Fe–Se) alloys have potential as attractive biodegradable bone–implant materials, given the antitumor properties of Se in cancer prevention and therapy. However, the fabrication of Fe–Se alloys is challenging due to the volatility of elemental Se and the significantly different melting points of Se and Fe. In this study, we successfully fabricated Fe–xSe (x = 0.2, 0.4, 0.6, 0.8, and 1 wt.%) alloys using suction casting, with FeSe compounds as the Se source. The microstructures, tensile properties, corrosion behavior, biocompatibility, antibacterial ability, and antitumor properties of the Fe–Se alloys were evaluated. The microstructures of the Fe–Se alloys were composed of α–Fe and FeSe phases. Among the Fe–Se alloys, Fe–0.6Se showed the best combination of tensile properties, with a yield strength of 1096.5 ± 7.2 MPa, an ultimate tensile strength of 1271.6 ± 6.3 MPa, and a fracture strain of 15.6 ± 3.3 %, and a degradation rate of 56.9 ± 0.4 μm/year. Moreover, the Fe–0.6Se alloy showed superb antibacterial ability against S. aureus , antitumor activity against 143B osteosarcoma cells, and osteogenicity and biocompatibility toward pre–osteoblast MC3T3–E1 cells. In summary, adding 0.2–1.0 wt.% Se to Fe does not affect the growth of healthy cells but effectively inhibits the growth and reproduction of tumor cells, and the Fe–0.6Se alloy is promising for orthopedic applications owing to its unique combination of mechanical and biofunctional properties. This work reports on Fe-xSe (x = 0.2, 0.4, 0.6, 0.8, and 1 wt.%) alloys fabricated using suction casting. The microstructures of the Fe–Se alloys were composed of α-Fe and FeSe phases. Among the Fe–Se alloys, the Fe-0.6Se showed the best combination of tensile properties, with a yield strength of 1058.6 ± 3.9 MPa, an ultimate tensile strength of 1134.1 ± 2.9 MPa, and a fracture strain of 16.8 ± 1.5 %, and a degradation rate of 56.9 ± 0.4 μm/year. Moreover, the Fe-0.6Se alloy showed superb antibacterial ability against S. aureus , antitumor activity against 143B osteosarcoma cells, and significant osteogenic ability and biocompatibility toward pre-osteoblast MC3T3-E1 cells. In summary, the Fe-0.6Se alloy is promising for orthopedic applications owing to its unique combination of mechanical and biofunctional properties. [Display omitted] [ABSTRACT FROM AUTHOR]

Zinc (Zn) and some of its alloys are recognized as promising biodegradable implant materials due to their acceptable biocompatibility, facile processability, and moderate degradation rate. Nevertheless, the limited mechanical properties and stability of as-cast Zn alloys hinder their clinical application. In this work, hot-rolled (HR) and hot-extruded (HE) Zn-5 wt.% gadolinium (Zn-5Gd) samples were prepared by casting and respectively combining with hot rolling and hot extrusion for bone-implant applications. Their microstructure evolution, mechanical properties, corrosion behavior, cytotoxicity, antibacterial ability, and in vitro and in vivo osteogenesis were systematically evaluated. The HR and HE Zn-5Gd exhibited significantly improved mechanical properties compared with those of their pure Zn counterparts and the HR Zn-5Gd showed a unique combination of tensile properties with an ultimate tensile strength of ∼311.6 MPa, yield strength of ∼236.5 MPa, and elongation of ∼40.6%, all of which are greater than the mechanical properties required for bone-implant materials. The HR and HE Zn-5Gd showed higher corrosion resistance than their pure Zn counterpart in Hanks' solution and the HE Zn-5Gd had the lowest corrosion rate of 155 µm/y measured by electrochemical corrosion and degradation rate of 26.9 µm/y measured by immersion testing. The HR and HE Zn-5Gd showed high cytocompatibility toward MC3T3-E1 and MG-63 cells, high antibacterial effects against S. aureus , and better in vitro osteogenic activity than their pure Zn counterparts. Furthermore, the HE Zn-5Gd exhibited better in vivo biocompatibility, osteogenesis, and osteointegration ability than pure Zn and pure Ti. This work reports the mechanical properties, corrosion behaviors, cytocompatibility, antibacterial ability, in vitro and in vivo osteogenesis of biodegradable Zn–Gd alloy for bone-implant applications. Our findings demonstrate that the hot-rolled (HR) Zn–5Gd showed a unique combination of tensile properties with an ultimate tensile strength of ∼311.6 MPa, yield strength of ∼236.5 MPa, and elongation of ∼40.6%. The HR and HE Zn-5Gd showed higher corrosion resistance than their pure Zn counterpart in Hanks' solution. The HR and HE Zn-5Gd showed high cytocompatibility toward MC3T3-E1 and MG-63 cells, good antibacterial effects against S. aureus , and better in vitro osteogenic activity. Furthermore, the HE Zn-5Gd exhibited better in vivo biocompatibility, osteogenesis, and osteointegration ability than pure Zn and pure Ti. [Display omitted] [ABSTRACT FROM AUTHOR]

Zn-Mn alloys are considered promising biodegradable metals for orthopedic applications due to their large elongation and favorable osteogenicity. However, the corrosion rate of Zn-Mn alloys could be improved to meet the degradation requirement for orthopedic implants. In this study, a Zn-1.5Mn alloy was prepared via high-pressure solid-solution (HPSS) treatment at 5 GPa and 380 °C for 1 h to cast ingots. Microstructural evaluation revealed the HPSS treatment caused a phase transition from a ζ-MnZn 13 phase to an ε-MnZn 3 phase. The electrode potential difference between the ε-MnZn 3 and the α-Zn was significantly larger than between the ζ-MnZn 13 and the α-Zn, leading to an accelerated corrosion rate of the HPSS-treated alloy. It showed an electrochemical corrosion rate of 0.343 mm/y and an immersion degradation rate of 0.028 mm/y, while the as-cast (AC) Zn-1.5Mn displayed an electrochemical corrosion rate of 0.216 mm/y and an immersion degradation rate of 0.026 mm/y. Further, the HPSS-treated Zn-1.5Mn exhibited a compressive yield strength of 202 MPa and a microhardness of 83.48 HV. In addition, the HPSS-treated Zn-1.5Mn exhibited a cell viability toward human umbilical vein endothelial cells (HUVEC) comparable to its AC and atmospheric pressure solid-solution-treated (APSS-treated) counterparts toward HUVEC, along with improved antibacterial activity. [Display omitted] • The Zn-Mn alloy undergoes a phase transition under high pressure solid solution. • The HPSS can control the mechanical and degradation properties of Zn-Mn alloy. • The ε-MnZn 3 phase of the new transition exhibits a higher potential difference. • The main strengthening mechanism of HPSS Zn-Mn alloy is solid solution strengthening. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) and some of its alloys are considered promising biodegradable metallic biomaterials for bone implant applications. The osteogenesis effect of Mg alloys is widely reported; however, the underlying mechanisms are still not clear. In this study, pure Mg, Mg-3Zn, and Mg-2Zn-1Mn were prepared, and their degradation behavior, biocompatibility, and osteogenesis effect were systematically assessed both in vitro and in vivo. Primary rat bone marrow-derived mesenchymal stem cells (BMSCs) were used to evaluate the biocompatibility of the prepared Mg alloys, and a rat femur fracture model was used to assess the stimulating effect of these alloys on bone-tissue formation. Mg-2Zn-1Mn showed higher corrosion resistance and more stable degradation behavior than pure Mg and Mg-3Zn. Extracts of the three materials showed significant stimulating effects on osteogenic differentiation of BMSCs along with non-cytotoxicity. Implantation of Mg-2Zn-1Mn wires into the femur of rats demonstrated superior histocompatibility, stable degradation, and notable promotion of osteogenesis without systemic toxicity. Moreover, the results of both in vitro and in vivo assessments demonstrated that bone morphogenetic proteins and fibroblast growth factor receptors are involved in the stimulating effect of Mg alloys. This work reports the degradation behavior, biocompatibility, and osteogenic effect of pure Mg and Mg-3Zn and Mg-2Zn-1Mn alloys in both in vitro and in vivo conditions. Mg-2Zn-1Mn showed higher corrosion resistance and more stable degradation behavior than pure Mg and Mg-3Zn. The extracts of the three materials showed a significant stimulating effect on osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) along with non-cytotoxicity. Mg-2Zn-1Mn wires implanted into the femur of rats showed good histocompatibility, stable degradation, and notable promotion of osteogenesis without systemic toxicity. The results of the present study suggest that bone morphogenetic proteins (BMPs) and fibroblast growth factor receptors (FGFRs) are involved in the stimulating effect of Mg alloys on osteogenesis. [Display omitted] [ABSTRACT FROM AUTHOR]

β -type titanium (Ti) alloys have been extensively investigated as orthopedic implant materials due to their unique combination of low elastic modulus, high specific strength, corrosion resistance, and biocompatibility. In this study the mechanical properties, corrosion behavior, friction and wear performance, and cytotoxicity of β -type Ti–24Nb–38Zr–2Mo (TNZM) and Ti–24Nb–38Zr–2Mo–0.1Sc (TNZMS) have been comparatively investigated for orthopedic applications. Cold-rolling (CR) and cold-rolling plus solution-treatment (CR+ST) were performed on the as-cast (AC) alloys and their microstructures and material properties were characterized. The impact of Sc addition on the mechanical and corrosion properties, friction and wear behavior, and in vitro cytocompatibility of the TNZMS alloy was assessed. The CR+ST TNZMS alloy exhibited the best combination of properties among all the alloy samples, with a yield strength of 780 MPa, ultimate strength of 809 MPa, elongation of 19%, Young's modulus of 65.4 GPa, and hardness of 265 HV. Electrochemical testing in Hanks' Solution indicated that the CR+ST TNZMS sample also showed the highest corrosion resistance with a corrosion potential of -0.234 V, corrosion current density of 0.07 µA/cm2, and corrosion rate of 1.2 µm/y. Friction and wear testing revealed that the TNZMS alloy showed higher wear resistance compared to the TNZM alloy and the wear resistance of the different samples was ranked CR > CR+ST > AC. Finally, both the CR+ST TNZM and TNZMS showed no-cytotoxicity towards MG-63 cells and the TNZMS exhibited slightly higher cytocompatibility than the TNZM alloy. This work reports the β -type Ti–24Nb–38Zr–2Mo (TNZM) and Ti–24Nb–38Zr–2Mo–0.1Sc (TNZMS) alloys fabricated by as-cast (AC), cold-rolling (CR), and cold-rolling plus solution-treatment (CR+ST) for potential orthopedic applications. The experimental results showed that the TNZMS alloy exhibited significantly enhanced mechanical, wear, and corrosion properties than those of TNZM alloy; and the CR+ST TNZMS possess a unique combination of the best mechanical and corrosion properties including a yield strength of 780 MPa, ultimate strength of 809 MPa, elongation of 19%, Young's modulus of 65.4 GPa, and corrosion rate of 1.2 µm/y in Hanks' Solution. Both the CR+ST TNZM and TNZMS alloys exhibited non-cytotoxicity towards MG-63 cells and TNZMS showed a higher cytocompatibility than that of TNZM. [Display omitted] [ABSTRACT FROM AUTHOR]

Zinc (Zn) and its alloys are receiving great attention as promising biodegradable materials due to their suitable corrosion resistance, good biocompatibility, and highly desirable biofunctionality. Nevertheless, the low mechanical strength of pure Zn impedes its practical clinical application and there have been calls for further research into the Zn alloys and thermomechanical processes to enhance their mechanical properties and biocompatibility. Here, we report on the alloying efficacy of rare earth elements (REEs) including erbium (Er), dysprosium (Dy), and holmium (Ho) on the microstructure, mechanical properties, corrosion and wear behavior, and in vitro biological properties of Zn–1Mg–0.1RE alloys. Microstructural characterization revealed that the addition of 0.1 wt.% REEs had a significant refining effect on the grain size of the α–Zn matrix and the second phases of the alloys. Alloying of the REEs and hot-rolling effectively improved the mechanical properties due to both precipitation strengthening of the second phases of ErZn 5 , DyZn 5 , and Ho 2 Zn 17 and grain-refinement strengthening. The highest ultimate tensile strength of 259.4 MPa and yield strength of 234.8 MPa with elongation of 16.8% were achieved in the hot-rolled Zn–1Mg–0.1Ho. Alloying of REEs also improved the wear and corrosion resistance, and slowed down the degradation rate in Hanks' solution. Zn–1Mg–0.1Er showed the highest cytocompatibility of MC3T3-E1 cells cultured directly on the alloy surface and of MG-63 cells cultured in the alloy extract. Zn–1Mg–0.1Dy showed the best anticoagulant property among all the alloys. Overall, these Zn–1Mg–0.1RE (Er, Dy, and Ho) alloys can be considered promising biodegradable metallic materials for orthopedic applications. Image, graphical abstract [ABSTRACT FROM AUTHOR]

In this study, porous iron (Fe)–manganese (Mn) alloys with high porosity were successfully prepared by sponge impregnation and sintering (SIS). The compositions of the porous Fe–Mn alloys were strongly dependent on the sintering temperature, and the Mn content was ~44, 30, and 12 wt.% for alloys sintered at 1100, 1150, and 1200 °C, respectively. The porous Fe–Mn alloys exhibited a well-interconnected porous structure with ~85% porosity and average pore size ranging from 375 to 500 um. The porous Fe-44Mn and Fe-30Mn alloys were mainly composed of a γ-austenite phase, while the porous Fe-12Mn was composed of an α-ferrite phase. The yield strength and elastic modulus of the porous Fe–Mn alloys ranged from 6 to 10 MPa and from 0.12 to 0.37 GPa, respectively, similar to those of cancellous bone. The degradation rate of the porous Fe–Mn alloys decreased over time during immersion in simulated body fluid (SBF), and was 1.0 mm/year for Fe-44Mn, 0.81 mm/year for Fe-30Mn, 0.41 mm/year for Fe-12Mn, and 0.33 mm/year for pure Fe after 14 d SBF immersion. Moreover, the porous Fe–Mn alloys exhibited good biocompatibility with clearly enhanced cell proliferation after direct culturing of osteoblastic MC3T3-E1 cells for 7 d. Thus, these porous Fe–Mn alloys can be anticipated to be promising biodegradable implant materials. This work reports on porous Fe-Mn alloys with high porosity, suitable mechanical properties and degradation rate, and good biocompatibility. The porous alloys prepared by sponge impregnation and sintering exhibited a well-interconnected porous structure with ~85% porosity and average pore size ranging from 375 to 500 um. The yield strength and elastic modulus of the porous alloys ranged from 6 to 10 MPa and from 0.12 to 0.37 GPa, respectively, similar to those of cancellous bone. The degradation rates in simulated body fluid (SBF) were ~1.0 mm/year for Fe-44Mn, 0.81 mm/year for Fe-30Mn, and 0.41 mm/year for Fe-12Mn, respectively. Moreover, the porous Fe-Mn alloys exhibited good biocompatibility with enhanced cell proliferation after direct culturing of osteoblastic MC3T3-E1 cells Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract: In this study 5, 10 and 15% β-Ca3(PO4)2/Mg–Zn composites were prepared through powder metallurgy methods, and their corrosion behavior and mechanical properties were studied in simulated body fluid (SBF) at 37°C. The 10% β-Ca3(PO4)2/Mg–Zn composite was selected for cytocompatibility assessment and in vivo biodegradation testing. The results identified the α-Mg, MgZn and β-Ca3(PO4)2 phases in these sintered composites. The density and elastic modulus of the β-Ca3(PO4)2/Mg–6% Zn composite match those of natural bone, and the strength is approximately double that of natural bone. The 10% β-Ca3(PO4)2/Mg–6% Zn composites exhibit good corrosion resistance, as determined by a 30day immersion test and electrochemical measurements in SBF at 37°C. The 10% β-Ca3(PO4)2/Mg–6% Zn composite is safe for cellular applications, with a cytotoxicity grade of ∼0–1 against L929 cells in in vitro testing. The β-Ca3(PO4)2/Mg–6% Zn composite also exhibits good biocompatibility with the tissue and the important visceral organs the heart, kidney and liver of experimental rabbits. The composite has a suitable degradation rate and improves the concrescence of a pre-broken bone. The corrosion products, such as Mg(OH)2 and Ca5(PO4)6(OH)2, can improve the biocompatibility of the β-Ca3(PO4)2/Mg–Zn composite. [Copyright &y& Elsevier]

In this study, in order to investigate the effects of alloying elements on the electrochemical behaviors of Al-based anodes, pure Al and Al-Mg-Ga-In alloys with different compositions (Al-0.25Mg-0.3Ga-0.3In, Al-1Mg-0.05Ga-0.15In and Al-2Mg-0.15Ga-0.05In (wt%)) were fabricated. The microstructure, corrosion behavior, electrochemical property, discharge performance and corroded morphology of the four experimental anodes were studied. Al-Mg-In-rich intermetallic compounds were observed in Al-Mg-Ga-In alloys. The results of the polarization curve and electrochemical impedance spectroscopy indicate that the addition of Mg acts as a critical component in improving the discharge activity of Al-based anode and contributes to a more negative electrode potential. According to the corrosion morphologies after discharge, it can be concluded that the addition of In element plays an essential part in forming corrosion pits on the surface of the anode while the addition of Ga element plays a vital role in destroying the surface passive layer to prevent passivation once corrosion starts. • Increasing Mg amount does activate Al-based anodes significantly. • Ga has a major contribution in activating anode than In. • In plays an essential part in forming corrosion pits. • Ga activates the surface of anodes and affects the morphology of corrosion products. • Al-2Mg-0.15Ga-0.05In alloy shows the best electrochemical performance as Al-based anode. [ABSTRACT FROM AUTHOR]

Mg-Al-Pb-Zn alloy is a typical anode material used for high-power seawater activated battery. The chemical composition of a series of Mg-Al-Pb-(Zn) alloys is optimized by a L 9 orthogonal array test and the effects of alloying elements, such as aluminium, lead and zinc, on electrochemical properties are investigated through signal-to-noise ratio (S/N) analysis. Microstructure characterization and half-cell test demonstrate that the selected optimal Mg-6%Al-7%Pb-0.5%Zn (wt%) alloy is a good candidate as an anode material for seawater activated battery application due to its high discharge activity, negative discharge potential in large current densities and comparatively higher anode utilization efficiency. The prototype battery assembled with Mg-6%Al-7%Pb-0.5%Zn alloy as anode and AgCl as cathode reveals excellent discharge performance, reaching a superior specific energy of 155 Wh·kg −1 . [ABSTRACT FROM AUTHOR]