Hard tissue repair materials that balance high strength with low modulus are highly promising,representing a transformative focus in applied biomaterials research.In this study,Ti-Nb alloys with high performance are p...Hard tissue repair materials that balance high strength with low modulus are highly promising,representing a transformative focus in applied biomaterials research.In this study,Ti-Nb alloys with high performance are prepared by a low-cost process for orthopedic applications.Phase composition,modulus,compressive strength and recovery properties are effectively manipulated by tailoring trace amounts of interstitial oxygen.With increasing oxygen concentration in sintered Ti-Nb alloys,theβ(body centered cubic)phase was stabilized due to the lattice distortion.The elastic modulus declined from 91 to 24 GPa.The compressive strength slightly decreased from 1595 to 1404 MPa and yield strength increased from 760 to 904 MPa.Additionally,the recovery properties were enhanced by the interstitial oxygen as a shape memory alloy.The utilization of trace oxygen serves to modulate the thermoelastic martensitic transformation in Ti-Nb alloys,thereby obtaining appropriate mechanical properties.A notable reduction in modulus is achieved while maintaining high strength,which facilitates the development of orthopedic implants capable of withstanding more complex forces.展开更多
Goethite(a-FeOOH)is one of the most abundant minerals on the Earth surface,occurring in temperate,tropical and equatorial climates.Fe in goethite can be substituted by many cations such as Al,Ni for instance.A large a...Goethite(a-FeOOH)is one of the most abundant minerals on the Earth surface,occurring in temperate,tropical and equatorial climates.Fe in goethite can be substituted by many cations such as Al,Ni for instance.A large amount of research has been conducted on the effect of varying elemental compositions(mainly Al-content)on the spectral features of goethites with most of the studies based on materials synthesized with different elemental ratios.The different elemental ratios,however,may not only affect the composition of the products but also their crystallinity and/or particle size and shape.Both parameters are known to affect results of both X-ray diffraction(XRD)and infrared spectroscopy(IR).These methods are predominantely used to characterize goethites.In the present study,therefore,a significant set of natural goethites was considered in order to investigate the effect of elemental composition on XRD and IR results.The focus was on crystallised samples which had a limited chemical variability but artefacts caused by the presence of admixtures could be excluded in most cases.First of all Rietveld refinement was optimized based on varying different parameters.A fairly good correlation of Rietveld derived crystallite sizes and specific surface area determined by N-adsorption(SSA)was found which proves the importance of considering the crystallite size parameters for Rietveld refinement and at the same times proves the quality of it.Using IR spectroscopy yet published relations of band position and Al-content could be confirmed despite the fact that the range of Al-contents was small.However,the band position of the Fe–O stretching,previously used as proxy for crystallinity assessment,was found to be least variable hence contradicting yet published results.Controversial results were also published for the effect of the Al-content on the position of the asymmetric FeOH stretching band at 450 cm.The goethites investigated in the present study indicate that the crystallite size determines the band position rather than the Al-content which is at least valid for the limited range of Al-contents.The results of the present study indicate that using synthetic sample sets bears the problem that more than one parameter might show systematic differences(e.g.crystallite size in a set of chemically varied goethites).The paper,therefore,provides IR reference data based on a set of natural well crystallised goethites.展开更多
The effect of annealing temperature(TA) at600-900℃ on structure and magnetic properties of the melt-spun Sm_(8.6)Fe_(85.9)Co_(4.3)Zr_(1.2) alloys and its nitrides was investigated.Results show that the melt-spun powd...The effect of annealing temperature(TA) at600-900℃ on structure and magnetic properties of the melt-spun Sm_(8.6)Fe_(85.9)Co_(4.3)Zr_(1.2) alloys and its nitrides was investigated.Results show that the melt-spun powder is TbCu7-type SmFe_(9) single phase.X-ray diffractometer(XRD) Rietveld refinement shows that the lattice parameter a increases,c and c/a decrease with the increase in T_(A) at600-700℃.This is due to the tendency of nitrogen entering into the 3f site(1/2,0,0) during the nitridation process,which is good for the magnetic properties.The phase transforms from TbCu7-type SmFe_(9) to Th_(2)Zn_(17)-type Sm_(2)Fe_(17) at above 800 0C.Scanning electron microscopy(SEM) images show that the amount of surface defects of melt-spun powder which are harmful for magnetic properties decreases at first and then increases as TA increases.The coercivity(H_(cj)) and maximum magnetic energy product((BH)_(max)) of its nitrides increase first and then decrease as a function of TA.And the remanence(B_(r))always shows a decrease.The optimal magnetic properties of H_(cj)=748 kA·m^(-1),B_(r)=0.92 T,(BH)_(max)=118 kJ·m^(-3) are obtained by annealing at 675℃ for 2 h and then nitriding at 460℃ for 10 h.展开更多
基金Project(52501069)supported by the National Natural Science Foundation of ChinaProject(GZC20233172)supported by the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(CPSF)Project(21B0121)supported by Hunan Provincial Education Department,China。
文摘Hard tissue repair materials that balance high strength with low modulus are highly promising,representing a transformative focus in applied biomaterials research.In this study,Ti-Nb alloys with high performance are prepared by a low-cost process for orthopedic applications.Phase composition,modulus,compressive strength and recovery properties are effectively manipulated by tailoring trace amounts of interstitial oxygen.With increasing oxygen concentration in sintered Ti-Nb alloys,theβ(body centered cubic)phase was stabilized due to the lattice distortion.The elastic modulus declined from 91 to 24 GPa.The compressive strength slightly decreased from 1595 to 1404 MPa and yield strength increased from 760 to 904 MPa.Additionally,the recovery properties were enhanced by the interstitial oxygen as a shape memory alloy.The utilization of trace oxygen serves to modulate the thermoelastic martensitic transformation in Ti-Nb alloys,thereby obtaining appropriate mechanical properties.A notable reduction in modulus is achieved while maintaining high strength,which facilitates the development of orthopedic implants capable of withstanding more complex forces.
基金Open Access funding enabled and organized by Projekt DEAL。
文摘Goethite(a-FeOOH)is one of the most abundant minerals on the Earth surface,occurring in temperate,tropical and equatorial climates.Fe in goethite can be substituted by many cations such as Al,Ni for instance.A large amount of research has been conducted on the effect of varying elemental compositions(mainly Al-content)on the spectral features of goethites with most of the studies based on materials synthesized with different elemental ratios.The different elemental ratios,however,may not only affect the composition of the products but also their crystallinity and/or particle size and shape.Both parameters are known to affect results of both X-ray diffraction(XRD)and infrared spectroscopy(IR).These methods are predominantely used to characterize goethites.In the present study,therefore,a significant set of natural goethites was considered in order to investigate the effect of elemental composition on XRD and IR results.The focus was on crystallised samples which had a limited chemical variability but artefacts caused by the presence of admixtures could be excluded in most cases.First of all Rietveld refinement was optimized based on varying different parameters.A fairly good correlation of Rietveld derived crystallite sizes and specific surface area determined by N-adsorption(SSA)was found which proves the importance of considering the crystallite size parameters for Rietveld refinement and at the same times proves the quality of it.Using IR spectroscopy yet published relations of band position and Al-content could be confirmed despite the fact that the range of Al-contents was small.However,the band position of the Fe–O stretching,previously used as proxy for crystallinity assessment,was found to be least variable hence contradicting yet published results.Controversial results were also published for the effect of the Al-content on the position of the asymmetric FeOH stretching band at 450 cm.The goethites investigated in the present study indicate that the crystallite size determines the band position rather than the Al-content which is at least valid for the limited range of Al-contents.The results of the present study indicate that using synthetic sample sets bears the problem that more than one parameter might show systematic differences(e.g.crystallite size in a set of chemically varied goethites).The paper,therefore,provides IR reference data based on a set of natural well crystallised goethites.
基金financially supported by the National Natural Science Foundation of China (No.51401028)。
文摘The effect of annealing temperature(TA) at600-900℃ on structure and magnetic properties of the melt-spun Sm_(8.6)Fe_(85.9)Co_(4.3)Zr_(1.2) alloys and its nitrides was investigated.Results show that the melt-spun powder is TbCu7-type SmFe_(9) single phase.X-ray diffractometer(XRD) Rietveld refinement shows that the lattice parameter a increases,c and c/a decrease with the increase in T_(A) at600-700℃.This is due to the tendency of nitrogen entering into the 3f site(1/2,0,0) during the nitridation process,which is good for the magnetic properties.The phase transforms from TbCu7-type SmFe_(9) to Th_(2)Zn_(17)-type Sm_(2)Fe_(17) at above 800 0C.Scanning electron microscopy(SEM) images show that the amount of surface defects of melt-spun powder which are harmful for magnetic properties decreases at first and then increases as TA increases.The coercivity(H_(cj)) and maximum magnetic energy product((BH)_(max)) of its nitrides increase first and then decrease as a function of TA.And the remanence(B_(r))always shows a decrease.The optimal magnetic properties of H_(cj)=748 kA·m^(-1),B_(r)=0.92 T,(BH)_(max)=118 kJ·m^(-3) are obtained by annealing at 675℃ for 2 h and then nitriding at 460℃ for 10 h.
