In order to develop the Mg-Zn-Ag metallic glasses(MGs)for biodegradable implant applications,the glass formation ability(GFA)and biocompatibility of Mg-Zn-Ag alloys were investigated using a combination of the calcula...In order to develop the Mg-Zn-Ag metallic glasses(MGs)for biodegradable implant applications,the glass formation ability(GFA)and biocompatibility of Mg-Zn-Ag alloys were investigated using a combination of the calculation of phase diagrams(CALPHAD)and experimental measurements.High GFA potentiality of two alloy series,specifically Mg_(96-x)Zn_xAg_(4)and Mg_(94-x)Zn_xAg_6(x=17,20,23,26,29,32,35),was predicted theoretically and then substantiated through experimental testing.X-ray diffraction(XRD)and differential scanning calorimetry(DSC)techniques were used to evaluate the crystallinity,GFA,and crystallization characteristics of these alloys.The results showed that compositions between Mg_(73)Zn_(23)Ag_(4)and Mg_(64)Zn_(32)Ag_(4)for Mg_(96-x)Zn_xAg_4,Mg_(66)Zn_(28)Ag_(6)and Mg_(63)Zn_(31)Ag_(6for)Mg_(94-x)Zn_xAg_(6)displayed a superior GFA.Notably,the GFA of the Mg_(96-x)Zn_xAg_(4)series was better than that of the Mg_(94-x)Zn_xAg_(6)series.Furthermore,the Mg_(70)Zn_(26)Ag_4,Mg_(74)Zn_(20)Ag_6,and Mg_(71)Zn_(23)Ag_(6)alloys showed acceptable corrosion rates,good cytocompatibility,and positive effects on cell proliferation.These characteristics make them suitable for applications in medical settings,potentially materials as biodegradable implants.展开更多
The microstructure,mechanical properties and corrosion behavior of quaternary degradable Mg−1Zn−0.2Ca−xAg(x=1,2,4 wt.%)alloy wires,intended as anastomotic nails,were investigated.It was found that these Ag-containing ...The microstructure,mechanical properties and corrosion behavior of quaternary degradable Mg−1Zn−0.2Ca−xAg(x=1,2,4 wt.%)alloy wires,intended as anastomotic nails,were investigated.It was found that these Ag-containing alloy wires mainly consist of Mg matrix and Ag17Mg54 phase,characterized by SEM,EDS,XRD and TEM.Tensile and knotting tests results demonstrate the superior mechanical properties of these alloy wires.Especially,Mg−1Zn−0.2Ca−4Ag alloy exhibits the highest mechanical properties,i.e.an ultimate tensile strength of 334 MPa and an elongation of 8.6%.Moreover,with increasing Ag content,the corrosion rates of these alloy wires remarkably increase due to the formation of more micro-galvanic coupling between Mg matrix and Ag17Mg54 phase,shown by mass loss and scanning Kelvin probe force microscopy(SKPFM)results.The present alloy can be completely degraded within 28 d,satisfying the property requirements of anastomotic nails.展开更多
The corrosion behaviour of Mg−6Gd−3Y−1Zn−0.3Ag(wt.%)alloy components with different sizes after cooling was investigated.The alloys in the small components(SC)cooled fast,which were composed ofα-Mg matrix and coarse ...The corrosion behaviour of Mg−6Gd−3Y−1Zn−0.3Ag(wt.%)alloy components with different sizes after cooling was investigated.The alloys in the small components(SC)cooled fast,which were composed ofα-Mg matrix and coarse long-period stacking ordered(LPSO)phases.The alloys in the large components(LC)cooled slowly,and there were thin lamellar LPSO phases precipitating inside the grains,except forα-Mg matrix and coarse LPSO phases.The hydrogen evolution test revealed that the corrosion rate of LC sample was higher than that of SC sample.Electrochemical impedance spectroscopy(EIS)test showed that the surface film on LC alloys provided worse protection.The corrosion morphologies indicated that the precipitation of the thin lamellar LPSO phases in LC sample caused severe micro-galvanic corrosion,which accelerated the rupture of the surface film.展开更多
The degradation behaviors of the as-extruded and solution treated Mg-3Zn-xAg(x=0,1,3,mass fraction,%)alloys,as well as as-extruded pure Mg,have been investigated by immersion tests in simulated body fluid(SBF)at37...The degradation behaviors of the as-extruded and solution treated Mg-3Zn-xAg(x=0,1,3,mass fraction,%)alloys,as well as as-extruded pure Mg,have been investigated by immersion tests in simulated body fluid(SBF)at37°C.The as-extruded Mg-Zn(-Ag)alloys contained Mg51Zn20and Ag17Mg54.While the quasi-single phase Mg-Zn(-Ag)alloys were obtained by solution treatment at400°C for8h.The quasi-single phase Mg-Zn(-Ag)alloys showed lower degradation rate and more homogeneous degradation than corresponding as-extruded Mg alloys.Degradation rate of solid-solution treated Mg-3Zn-1Ag and Mg-3Zn-3Ag was approximately half that of corresponding as-extruded Mg alloy.Moreover,the degradation rate of solid-solution treated Mg-3Zn and Mg-3Zn-1Ag was equivalent to that of as-extruded pure Mg.However,heterogeneous degradation also occurred in quasi-single phase Mg-Zn-Ag alloys,compared to pure Mg.So,preparing complete single-phase Mg alloys could be a potential and feasible way to improve the corrosion resistance.展开更多
The effect of aging on microstructure of Mg-Zn-Er alloys at 473 K was investigated using hardness measurement,scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results indicated that both...The effect of aging on microstructure of Mg-Zn-Er alloys at 473 K was investigated using hardness measurement,scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results indicated that both Mg3.8Zn1.5Er and Mg5Zn2.0Er alloys exhibited visible age-hardening effect,especially the latter alloy.Microstructure analysis showed that,after being aged,lots of fine MgZn2 phases with hexagonal structure were found in the α-Mg matrix.Comparing with Mg3.8Zn1.5Er alloy,the accelerated hardenin...展开更多
The effect of retrogression and re-aging(RRA) heat treatment on the microstructure and mechanical properties of a low frequency electromagnetic casting alloy as Al-9.99%Zn-1.72%Cu-2.5%Mg-0.13%Zr was investigated by te...The effect of retrogression and re-aging(RRA) heat treatment on the microstructure and mechanical properties of a low frequency electromagnetic casting alloy as Al-9.99%Zn-1.72%Cu-2.5%Mg-0.13%Zr was investigated by tensile properties test, Vickers hardness, electrical conductivity test, DSC analysis, SEM and TEM observation. The results show that RRA heat treatment can improve the stress corrosion cracking(SCC) properties with retention of the high strength of T6 level. After preaging at 100 ℃ for 24 h, retrogression at 200 ℃ for 7 min, and then re-aging at 100 ℃ for 24 h, the alloy obtains tensile strength up to 795 MPa, yield strength up to 767 MPa, maintains 9.1% elongation, and electric conductivity of 35.6%IACS. TEM observation shows that the re-dissolution of GP zone and η’ phase in the early stage of regression leads to the decrease of hardness, then the increase in the volume fraction of η’ and η phases leads to the increase again in the peak value, and finally the general coarsening of all particles results in a softening of the alloy. Meanwhile it is found that the conventional T6 heat treatment as the preaging and re-aging regime is not the optimum regime to the RRA treatment of the high-zinc content super-high strength aluminum alloy.展开更多
基金the financial supports from the Shenzhen Basic Research Project,China(No.JCYJ20170815153210359)the National Natural Science Foundation of China(No.12174210)。
文摘In order to develop the Mg-Zn-Ag metallic glasses(MGs)for biodegradable implant applications,the glass formation ability(GFA)and biocompatibility of Mg-Zn-Ag alloys were investigated using a combination of the calculation of phase diagrams(CALPHAD)and experimental measurements.High GFA potentiality of two alloy series,specifically Mg_(96-x)Zn_xAg_(4)and Mg_(94-x)Zn_xAg_6(x=17,20,23,26,29,32,35),was predicted theoretically and then substantiated through experimental testing.X-ray diffraction(XRD)and differential scanning calorimetry(DSC)techniques were used to evaluate the crystallinity,GFA,and crystallization characteristics of these alloys.The results showed that compositions between Mg_(73)Zn_(23)Ag_(4)and Mg_(64)Zn_(32)Ag_(4)for Mg_(96-x)Zn_xAg_4,Mg_(66)Zn_(28)Ag_(6)and Mg_(63)Zn_(31)Ag_(6for)Mg_(94-x)Zn_xAg_(6)displayed a superior GFA.Notably,the GFA of the Mg_(96-x)Zn_xAg_(4)series was better than that of the Mg_(94-x)Zn_xAg_(6)series.Furthermore,the Mg_(70)Zn_(26)Ag_4,Mg_(74)Zn_(20)Ag_6,and Mg_(71)Zn_(23)Ag_(6)alloys showed acceptable corrosion rates,good cytocompatibility,and positive effects on cell proliferation.These characteristics make them suitable for applications in medical settings,potentially materials as biodegradable implants.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(51671017 and 51971020)the Beijing Municipal Natural Science Foundation,China(2202033)+2 种基金Beijing Laboratory of Metallic Materials and Processing for Modern Transportation,China,the Fundamental Research Funds for the Central Universities,China(FRF-IC-19-015)the Major State Research and Development Program of China(2016YFB0300801)the Opening Research Fund of State Key Laboratory for Advanced Metals and Materials,China(2018-Z04).
文摘The microstructure,mechanical properties and corrosion behavior of quaternary degradable Mg−1Zn−0.2Ca−xAg(x=1,2,4 wt.%)alloy wires,intended as anastomotic nails,were investigated.It was found that these Ag-containing alloy wires mainly consist of Mg matrix and Ag17Mg54 phase,characterized by SEM,EDS,XRD and TEM.Tensile and knotting tests results demonstrate the superior mechanical properties of these alloy wires.Especially,Mg−1Zn−0.2Ca−4Ag alloy exhibits the highest mechanical properties,i.e.an ultimate tensile strength of 334 MPa and an elongation of 8.6%.Moreover,with increasing Ag content,the corrosion rates of these alloy wires remarkably increase due to the formation of more micro-galvanic coupling between Mg matrix and Ag17Mg54 phase,shown by mass loss and scanning Kelvin probe force microscopy(SKPFM)results.The present alloy can be completely degraded within 28 d,satisfying the property requirements of anastomotic nails.
基金the financial supports from the National Natural Science foundation of China(Nos.51574291,51874367).
文摘The corrosion behaviour of Mg−6Gd−3Y−1Zn−0.3Ag(wt.%)alloy components with different sizes after cooling was investigated.The alloys in the small components(SC)cooled fast,which were composed ofα-Mg matrix and coarse long-period stacking ordered(LPSO)phases.The alloys in the large components(LC)cooled slowly,and there were thin lamellar LPSO phases precipitating inside the grains,except forα-Mg matrix and coarse LPSO phases.The hydrogen evolution test revealed that the corrosion rate of LC sample was higher than that of SC sample.Electrochemical impedance spectroscopy(EIS)test showed that the surface film on LC alloys provided worse protection.The corrosion morphologies indicated that the precipitation of the thin lamellar LPSO phases in LC sample caused severe micro-galvanic corrosion,which accelerated the rupture of the surface film.
基金Projects(51371046,51525101,U1610253)supported by the National Natural Science Foundation of ChinaProject(NECT-12-0109)supported by the Program for New Century Excellent Talents in University,China+1 种基金Projects(N130510002,N141008001)supported by the Fundamental Research Funds for the Central Universities,ChinaProject supported by the Doctoral Thesis Cultivation Program of Northeastern University,China
文摘The degradation behaviors of the as-extruded and solution treated Mg-3Zn-xAg(x=0,1,3,mass fraction,%)alloys,as well as as-extruded pure Mg,have been investigated by immersion tests in simulated body fluid(SBF)at37°C.The as-extruded Mg-Zn(-Ag)alloys contained Mg51Zn20and Ag17Mg54.While the quasi-single phase Mg-Zn(-Ag)alloys were obtained by solution treatment at400°C for8h.The quasi-single phase Mg-Zn(-Ag)alloys showed lower degradation rate and more homogeneous degradation than corresponding as-extruded Mg alloys.Degradation rate of solid-solution treated Mg-3Zn-1Ag and Mg-3Zn-3Ag was approximately half that of corresponding as-extruded Mg alloy.Moreover,the degradation rate of solid-solution treated Mg-3Zn and Mg-3Zn-1Ag was equivalent to that of as-extruded pure Mg.However,heterogeneous degradation also occurred in quasi-single phase Mg-Zn-Ag alloys,compared to pure Mg.So,preparing complete single-phase Mg alloys could be a potential and feasible way to improve the corrosion resistance.
基金supported by National Major Fundamental Research Program of China (2007CB613706)
文摘The effect of aging on microstructure of Mg-Zn-Er alloys at 473 K was investigated using hardness measurement,scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results indicated that both Mg3.8Zn1.5Er and Mg5Zn2.0Er alloys exhibited visible age-hardening effect,especially the latter alloy.Microstructure analysis showed that,after being aged,lots of fine MgZn2 phases with hexagonal structure were found in the α-Mg matrix.Comparing with Mg3.8Zn1.5Er alloy,the accelerated hardenin...
基金Project(2001AA332030) supported by the National Hi-Tech Research and Development Program of China
文摘The effect of retrogression and re-aging(RRA) heat treatment on the microstructure and mechanical properties of a low frequency electromagnetic casting alloy as Al-9.99%Zn-1.72%Cu-2.5%Mg-0.13%Zr was investigated by tensile properties test, Vickers hardness, electrical conductivity test, DSC analysis, SEM and TEM observation. The results show that RRA heat treatment can improve the stress corrosion cracking(SCC) properties with retention of the high strength of T6 level. After preaging at 100 ℃ for 24 h, retrogression at 200 ℃ for 7 min, and then re-aging at 100 ℃ for 24 h, the alloy obtains tensile strength up to 795 MPa, yield strength up to 767 MPa, maintains 9.1% elongation, and electric conductivity of 35.6%IACS. TEM observation shows that the re-dissolution of GP zone and η’ phase in the early stage of regression leads to the decrease of hardness, then the increase in the volume fraction of η’ and η phases leads to the increase again in the peak value, and finally the general coarsening of all particles results in a softening of the alloy. Meanwhile it is found that the conventional T6 heat treatment as the preaging and re-aging regime is not the optimum regime to the RRA treatment of the high-zinc content super-high strength aluminum alloy.
