Magnetostrictive Fe-Ga alloys have captivated substantial focus in biomedical applications because of their exceptional transition efficiency and favorable cytocompatibility.Nevertheless,Fe-Ga alloys always exhibit fr...Magnetostrictive Fe-Ga alloys have captivated substantial focus in biomedical applications because of their exceptional transition efficiency and favorable cytocompatibility.Nevertheless,Fe-Ga alloys always exhibit frustrating magnetostriction coefficients when presented in bulk dimensions.It is well-established that the magnetostrictive performance of Fe-Ga alloys is intimately linked to their phase and crystal structures.In this study,various concentrations of boron(B)were doped into Fe_(81)Ga_(19) alloys via the laser-beam powder bed fusion(LPBF)technique to tailor the crystal and phase structures,thereby improving the magnetostrictive performance.The results revealed the capacity for quick solidification of the LPBF process in expediting the solid solution of B element,which increased both lattice distortion and dislocations within the Fe-Ga matrix.These factors contributed to an elevation in the density of the modified-D0_(3) phase structure.Moreover,the prepared Fe-Ga-B alloys also exhibited a(001)preferred grain orientation caused by the high thermal gradients during the LPBF process.As a result,a maximum magnetostriction coefficient of 105 ppm was achieved in the(Fe_(81)Ga_(19))_(98.5)B_(1.5) alloy.In alternating magnetic fields,all the LPBF-prepared alloys showed good dynamic magnetostriction response without visible hysteresis,while the(Fe_(81)Ga_(19))_(98.5)B_(1.5) alloy presented a notable enhancement of~30%in magnetostriction coefficient when compared with the Fe_(81)Ga_(19) alloy.Moreover.the(Fe_(81)Ga_(19))_(98.5)B_(1.5) alloy exhibited favorable biocompatibility and osteogenesis,as confirmed by increased alkaline phosphatase(ALP)activity and the formation of mineralized nodules.These findings suggest that the B-doped Fe-Ga alloys combined with the LPBF technique hold promise for the development of bulk magnetostrictive alloys that are applicable for bone repair applications.展开更多
Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.Howe...Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.However,the as-built part usually exhibits undesirable microstructure and unsatisfactory performance.In this work,WE43 parts were firstly fabricated by PBF-LB and then subjected to heat treatment.Although a high densification rate of 99.91%was achieved using suitable processes,the as-built parts exhibited anisotropic and layeredmicrostructure with heterogeneously precipitated Nd-rich intermetallic.After heat treatment,fine and nano-scaled Mg24Y5particles were precipitated.Meanwhile,theα-Mg grainsunderwent recrystallization and turned coarsened slightly,which effectively weakened thetexture intensity and reduced the anisotropy.As a consequence,the yield strength and ultimate tensile strength were significantly improved to(250.2±3.5)MPa and(312±3.7)MPa,respectively,while the elongation was still maintained at a high level of 15.2%.Furthermore,the homogenized microstructure reduced the tendency of localized corrosion and favoredthe development of uniform passivation film.Thus,the degradation rate of WE43 parts was decreased by an order of magnitude.Besides,in-vitro cell experiments proved their favorable biocompatibility.展开更多
The DLBSW（ dual laser-beam bilateral synchronous welding） technology of T-type joint has been widely used for the connection of skins and stringers in airplane industry. To understand the thermodynamic and mechanica...The DLBSW（ dual laser-beam bilateral synchronous welding） technology of T-type joint has been widely used for the connection of skins and stringers in airplane industry. To understand the thermodynamic and mechanical behavior of this process, it is necessary to establish a reasonable heat source model. Two different surface-body combination heat source models are adopted in this paper. Both models use the Gaussian surface heat source model and one is combined with the cone body heat source model and the other is combined with Gaussian rotator body heat source model. The simulation results of these two different models are investigated. And the temperature field results of DLBSW process for T-joint with two different heat sources are discussed. It is indicated that the combination heat source model is effective to simulate the DLBSW process and the current study is useful for more profound research in this field.展开更多
Magnetostrictive Fe-Ga alloys have been demonstrated potentialities for numerous applications,whereas,suffering a tradeoff between large magnetostrictive strain and high sensitivity.Herein,bulk polycrystalline Fe81Ga1...Magnetostrictive Fe-Ga alloys have been demonstrated potentialities for numerous applications,whereas,suffering a tradeoff between large magnetostrictive strain and high sensitivity.Herein,bulk polycrystalline Fe81Ga19 alloys were prepared by laser-beam powder bed fusion(LPBF)and then annealed in magnetic field for manipulating the comprehensive magnetostrictive properties.Results indicate that<001>oriented grains are developed in the LPBF-prepared Fe81Ga19 alloys due to high temperature gradient.After magnetic field annealing(MFA),the magnetic domains within the alloys gradually transformed into well-arranged stripe domains,especially,flat and smooth 90°domains were established in the alloys annealed at 2600 Oe.As a result,the induced<001>orientation grains and 90°domains contributed to an improved effective magnetic anisotropy constant(57.053 kJ/m^(3)),leading to an enhanced magnetostrictive strain of 92 ppm.Moreover,the MFA-treated alloys also displayed enhanced magnetostrictive sensitivity(0.097 ppm/Oe)owing to the smooth domain structures and low dislocation densities,demonstrating a fruitful strain-sensitivity synergy.In addition,good magnetostrictive dynamic response and enhanced compressive yield strength were also observed for the prepared alloys.This work demonstrates that LPBF and MFA might be an attractive strategy to resolve the tradeoff between strain and sensitivity,providing a basis for the preparation of high-performance magnetostrictive materials.展开更多
Fe-Ga-based alloys are considered promising magnetostrictive candidates because of their high permeability and favorable mechanical properties.However,currently developed Fe-Ga-based alloys often suffer from a limited...Fe-Ga-based alloys are considered promising magnetostrictive candidates because of their high permeability and favorable mechanical properties.However,currently developed Fe-Ga-based alloys often suffer from a limited capability for microstructure manipulation,which restricts their magnetostrictive performance.To address this limitation,this study proposes a novel strategy combining laser-beam powder bed fusion(LPBF)and aging treatment to modulate the microstructure and enhance magnetostrictive properties of Fe-Ga-B alloys.Considering the positive influence of B element on magnetostrictive property and ductility,B-doped magnetostrictive Fe-Ga alloys were prepared via the LPBF process and then aged at 600℃for varying times(1,2,and 3 h,respectively).The LPBF process,characterized by high thermal gradients and rapid solidification,produced a microstructure featuring<001>oriented grains and sparse m-D0_(3)nanoprecipitates embedded in an A2 matrix.After the aging treatment,sufficient nucleation and growth of nanoprecipitates were enhanced.Specifically,the sample aged for 2 h developed a high density of larger m-D0_(3)nanoprecipitates.This optimized microstructure yielded a high magnetostrictive strain of(109±12)ppm and a substantially reduced saturation field—decreased by~49.1%compared to the as-fabricated state—primarily due to the synergistic effect of the<001>texture and the dense nanoprecipitates.Moreover,all the prepared alloys exhibited good soft-magnetic characteristics and comparable mechanical properties.Therefore,the combination of LPBF and aging treatment offers a promising route for tailoring the macro/microstructure and performance of magnetostrictive Fe-Ga alloys for diverse applications.展开更多
激光无线传能(Laser Wireless Power Transmission,LWPT)系统中,传能激光光束质量直接影响传能效率,为了提高传能光束质量,提出了一种基于反高斯算法的激光光场匀化策略:首先建立激光光束的高斯数学模型,进而求出该高斯函数的反函数,得...激光无线传能(Laser Wireless Power Transmission,LWPT)系统中,传能激光光束质量直接影响传能效率,为了提高传能光束质量,提出了一种基于反高斯算法的激光光场匀化策略:首先建立激光光束的高斯数学模型,进而求出该高斯函数的反函数,得到对应的反高斯函数,再将该高斯函数与反高斯函数相乘,则得到一个常数。由此表明,高斯激光光束通过反高斯处理后,可以实现匀化;基于该策略,设计了反高斯光场匀化方案置,以此构建了基于反高斯匀化的激光无线传能系统模型。仿真实验结果表明,反高斯匀化策略与现有的激光光束整形方法相比,在不依赖复杂光学元件组与加工精度要求的前提下,光束发散角为6 mrad,光强均匀度达到了83%。由此可见,匀化效果明显,为激光无线传能系统效率提升提供了新的解决方案。展开更多
电子束注入器是决定自由电子激光太赫兹源(Free Electron Laser for Terahertz,FEL-THz)性能的核心部件,基于射频加速器的注入器能够产生驱动高功率THz辐射所需的高品质电子束。同时,出于商业化和市场化的考虑,注入器还需具备结构紧凑...电子束注入器是决定自由电子激光太赫兹源(Free Electron Laser for Terahertz,FEL-THz)性能的核心部件,基于射频加速器的注入器能够产生驱动高功率THz辐射所需的高品质电子束。同时,出于商业化和市场化的考虑,注入器还需具备结构紧凑的特点。采用独立调谐式结构(Independently Tunable Cavity,ITC)的束流注入器具有平衡高品质、低成本以及紧凑性的优势,在大功率FEL-THz装置小型化方面有广阔的应用前景。然而,随着束线长度的缩短和装置整体规模的压缩,注入器在运行过程中面临着在线调节手段和诊断能力不足等挑战。本文依托华中科技大学与中国科学技术大学共建的一台紧凑型FEL-THz注入器,首先介绍其基于ITC结构的优化思路和设计结果,然后在系统稳定的基础上,重点阐述调试和运行过程中所涉及的束流间接诊断和系统优化措施,并结合束流动力学仿真和在线实验开展了相关方案和研究的验证。仿真和实验结果均表明,通过优化设计并结合间接诊断技术,ITC注入器能够兼顾FEL-THz高功率和小型化的需求,而间接诊断技术的应用也能够弥补调试过程中诊断手段不足的问题,为ITC注入器的进一步推广奠定了基础。展开更多
基金supported by the National Natural Science Foundation of China(Nos.52275395,51935014,and 82072084)the Science and Technology Innovation Program of Hunan Province(No.2023RC3046)+4 种基金the Young Elite Scientists Sponsorship Program byCAST(No.2020QNRC002)the NationalKeyResearchand Development Program of China(No.2023YFB4605800)the Central South University Innovation-Driven Research Programme(No.2023CXQD023)the Jiangxi Provincial Natural Science Foundation of China(No.20224ACB204013)the Project of State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University.
文摘Magnetostrictive Fe-Ga alloys have captivated substantial focus in biomedical applications because of their exceptional transition efficiency and favorable cytocompatibility.Nevertheless,Fe-Ga alloys always exhibit frustrating magnetostriction coefficients when presented in bulk dimensions.It is well-established that the magnetostrictive performance of Fe-Ga alloys is intimately linked to their phase and crystal structures.In this study,various concentrations of boron(B)were doped into Fe_(81)Ga_(19) alloys via the laser-beam powder bed fusion(LPBF)technique to tailor the crystal and phase structures,thereby improving the magnetostrictive performance.The results revealed the capacity for quick solidification of the LPBF process in expediting the solid solution of B element,which increased both lattice distortion and dislocations within the Fe-Ga matrix.These factors contributed to an elevation in the density of the modified-D0_(3) phase structure.Moreover,the prepared Fe-Ga-B alloys also exhibited a(001)preferred grain orientation caused by the high thermal gradients during the LPBF process.As a result,a maximum magnetostriction coefficient of 105 ppm was achieved in the(Fe_(81)Ga_(19))_(98.5)B_(1.5) alloy.In alternating magnetic fields,all the LPBF-prepared alloys showed good dynamic magnetostriction response without visible hysteresis,while the(Fe_(81)Ga_(19))_(98.5)B_(1.5) alloy presented a notable enhancement of~30%in magnetostriction coefficient when compared with the Fe_(81)Ga_(19) alloy.Moreover.the(Fe_(81)Ga_(19))_(98.5)B_(1.5) alloy exhibited favorable biocompatibility and osteogenesis,as confirmed by increased alkaline phosphatase(ALP)activity and the formation of mineralized nodules.These findings suggest that the B-doped Fe-Ga alloys combined with the LPBF technique hold promise for the development of bulk magnetostrictive alloys that are applicable for bone repair applications.
基金supported by the following funds:National Natural Science Foundation of China(51935014,52165043)Jiangxi Provincial Cultivation Program for Academic and Technical Leaders of Major Subjects(20225BCJ23008)+1 种基金Jiangxi Provincial Natural Science Foundation(20224ACB204013,20224ACB214008)Scientific Research Project of Anhui Universities(KJ2021A1106)。
文摘Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.However,the as-built part usually exhibits undesirable microstructure and unsatisfactory performance.In this work,WE43 parts were firstly fabricated by PBF-LB and then subjected to heat treatment.Although a high densification rate of 99.91%was achieved using suitable processes,the as-built parts exhibited anisotropic and layeredmicrostructure with heterogeneously precipitated Nd-rich intermetallic.After heat treatment,fine and nano-scaled Mg24Y5particles were precipitated.Meanwhile,theα-Mg grainsunderwent recrystallization and turned coarsened slightly,which effectively weakened thetexture intensity and reduced the anisotropy.As a consequence,the yield strength and ultimate tensile strength were significantly improved to(250.2±3.5)MPa and(312±3.7)MPa,respectively,while the elongation was still maintained at a high level of 15.2%.Furthermore,the homogenized microstructure reduced the tendency of localized corrosion and favoredthe development of uniform passivation film.Thus,the degradation rate of WE43 parts was decreased by an order of magnitude.Besides,in-vitro cell experiments proved their favorable biocompatibility.
基金The research is sponsored by the Shanghai STCSM Project of the Postdoctoral Science Research Assistant Plan （10R21421200）, the National Natural Science Foundation of China （50904038） and the China Postdoctoral Science Foundation （20100470064）.
文摘The DLBSW（ dual laser-beam bilateral synchronous welding） technology of T-type joint has been widely used for the connection of skins and stringers in airplane industry. To understand the thermodynamic and mechanical behavior of this process, it is necessary to establish a reasonable heat source model. Two different surface-body combination heat source models are adopted in this paper. Both models use the Gaussian surface heat source model and one is combined with the cone body heat source model and the other is combined with Gaussian rotator body heat source model. The simulation results of these two different models are investigated. And the temperature field results of DLBSW process for T-joint with two different heat sources are discussed. It is indicated that the combination heat source model is effective to simulate the DLBSW process and the current study is useful for more profound research in this field.
基金supported by the following funds:The Natural Science Foundation of China(52275395,51935014,82072084)The Science and Technology Innovation Program of Hunan Province(2023RC3046)+5 种基金Young Elite Scientists Sponsorship Program by CAST(2020QNRC002)National Key Research and Development Program of China(2023YFB4605800)Central South University Innovation-Driven Research Programme(2023CXQD023)JiangXi Provincial Natural Science Foundation of China(20224ACB204013)The Project of State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South UniversityThe Fundamental Research Funds for the Central Universities of Central South University(1053320230182).
文摘Magnetostrictive Fe-Ga alloys have been demonstrated potentialities for numerous applications,whereas,suffering a tradeoff between large magnetostrictive strain and high sensitivity.Herein,bulk polycrystalline Fe81Ga19 alloys were prepared by laser-beam powder bed fusion(LPBF)and then annealed in magnetic field for manipulating the comprehensive magnetostrictive properties.Results indicate that<001>oriented grains are developed in the LPBF-prepared Fe81Ga19 alloys due to high temperature gradient.After magnetic field annealing(MFA),the magnetic domains within the alloys gradually transformed into well-arranged stripe domains,especially,flat and smooth 90°domains were established in the alloys annealed at 2600 Oe.As a result,the induced<001>orientation grains and 90°domains contributed to an improved effective magnetic anisotropy constant(57.053 kJ/m^(3)),leading to an enhanced magnetostrictive strain of 92 ppm.Moreover,the MFA-treated alloys also displayed enhanced magnetostrictive sensitivity(0.097 ppm/Oe)owing to the smooth domain structures and low dislocation densities,demonstrating a fruitful strain-sensitivity synergy.In addition,good magnetostrictive dynamic response and enhanced compressive yield strength were also observed for the prepared alloys.This work demonstrates that LPBF and MFA might be an attractive strategy to resolve the tradeoff between strain and sensitivity,providing a basis for the preparation of high-performance magnetostrictive materials.
基金supported by the Hunan Provincial Natural Science Foundation of China(Grant No.2025JJ30015)the National Natural Science Foundation of China(Grant Nos.52571276,52275395,U24A20120,52475362)+4 种基金the Science and Technology Innovation Program of Hunan Province(Grant No.2023RC3046)the National Key Research and Development Program of China(Grant No.2023YFB4605800)the Central South University Innovation-driven Research Programme(Grant No.2023CXQD023)the Jiangxi Provincial Natural Science Foundation of China(Grant No.20224ACB204013)the Project of State Key Laboratory of Precision Manufacturing for Extreme Service Performance of Central South University and the Fundamental Research Funds for the Central Universities of Central South University(Grant No.1053320230182)。
文摘Fe-Ga-based alloys are considered promising magnetostrictive candidates because of their high permeability and favorable mechanical properties.However,currently developed Fe-Ga-based alloys often suffer from a limited capability for microstructure manipulation,which restricts their magnetostrictive performance.To address this limitation,this study proposes a novel strategy combining laser-beam powder bed fusion(LPBF)and aging treatment to modulate the microstructure and enhance magnetostrictive properties of Fe-Ga-B alloys.Considering the positive influence of B element on magnetostrictive property and ductility,B-doped magnetostrictive Fe-Ga alloys were prepared via the LPBF process and then aged at 600℃for varying times(1,2,and 3 h,respectively).The LPBF process,characterized by high thermal gradients and rapid solidification,produced a microstructure featuring<001>oriented grains and sparse m-D0_(3)nanoprecipitates embedded in an A2 matrix.After the aging treatment,sufficient nucleation and growth of nanoprecipitates were enhanced.Specifically,the sample aged for 2 h developed a high density of larger m-D0_(3)nanoprecipitates.This optimized microstructure yielded a high magnetostrictive strain of(109±12)ppm and a substantially reduced saturation field—decreased by~49.1%compared to the as-fabricated state—primarily due to the synergistic effect of the<001>texture and the dense nanoprecipitates.Moreover,all the prepared alloys exhibited good soft-magnetic characteristics and comparable mechanical properties.Therefore,the combination of LPBF and aging treatment offers a promising route for tailoring the macro/microstructure and performance of magnetostrictive Fe-Ga alloys for diverse applications.
文摘激光无线传能(Laser Wireless Power Transmission,LWPT)系统中,传能激光光束质量直接影响传能效率,为了提高传能光束质量,提出了一种基于反高斯算法的激光光场匀化策略:首先建立激光光束的高斯数学模型,进而求出该高斯函数的反函数,得到对应的反高斯函数,再将该高斯函数与反高斯函数相乘,则得到一个常数。由此表明,高斯激光光束通过反高斯处理后,可以实现匀化;基于该策略,设计了反高斯光场匀化方案置,以此构建了基于反高斯匀化的激光无线传能系统模型。仿真实验结果表明,反高斯匀化策略与现有的激光光束整形方法相比,在不依赖复杂光学元件组与加工精度要求的前提下,光束发散角为6 mrad,光强均匀度达到了83%。由此可见,匀化效果明显,为激光无线传能系统效率提升提供了新的解决方案。
文摘电子束注入器是决定自由电子激光太赫兹源(Free Electron Laser for Terahertz,FEL-THz)性能的核心部件,基于射频加速器的注入器能够产生驱动高功率THz辐射所需的高品质电子束。同时,出于商业化和市场化的考虑,注入器还需具备结构紧凑的特点。采用独立调谐式结构(Independently Tunable Cavity,ITC)的束流注入器具有平衡高品质、低成本以及紧凑性的优势,在大功率FEL-THz装置小型化方面有广阔的应用前景。然而,随着束线长度的缩短和装置整体规模的压缩,注入器在运行过程中面临着在线调节手段和诊断能力不足等挑战。本文依托华中科技大学与中国科学技术大学共建的一台紧凑型FEL-THz注入器,首先介绍其基于ITC结构的优化思路和设计结果,然后在系统稳定的基础上,重点阐述调试和运行过程中所涉及的束流间接诊断和系统优化措施,并结合束流动力学仿真和在线实验开展了相关方案和研究的验证。仿真和实验结果均表明,通过优化设计并结合间接诊断技术,ITC注入器能够兼顾FEL-THz高功率和小型化的需求,而间接诊断技术的应用也能够弥补调试过程中诊断手段不足的问题,为ITC注入器的进一步推广奠定了基础。
