Copper manufactured by laser powder bed fusion(LPBF)process typically exhibits poor strength-ductility coordination,and the addition of strengthening phases is an effective way to address this issue.To explore the eff...Copper manufactured by laser powder bed fusion(LPBF)process typically exhibits poor strength-ductility coordination,and the addition of strengthening phases is an effective way to address this issue.To explore the effects of strengthening phases on Cu,Cu-carbon nanotubes(CNTs)composites were prepared using LPBF technique with Cu-CNTs mixed powder as the matrix.The formability,microstructure,mechanical properties,electrical conductivity,and thermal properties were studied.The result shows that the prepared composites have high relative density.The addition of CNTs results in inhomogeneous equiaxed grains at the edges of the molten pool and columnar grains at the center.Compared with pure copper,the overall mechanical properties of the composite are improved:tensile strength increases by 52.8%and elongation increases by 146.4%;the electrical and thermal properties are also enhanced:thermal conductivity increases by 10.8%and electrical conductivity increases by 12.7%.展开更多
In this study,carbon nanotubes(CNTs)/AlSi10Mg composite parts with CNTs contents ranging from 0.0 to 2.0wt.%were successfully fabricated via laser powder bed fusion(LPBF)with laser scan speeds ranging from 900 to 1,90...In this study,carbon nanotubes(CNTs)/AlSi10Mg composite parts with CNTs contents ranging from 0.0 to 2.0wt.%were successfully fabricated via laser powder bed fusion(LPBF)with laser scan speeds ranging from 900 to 1,900 mm·s^(-1).Uniform dispersion of CNTs in the powders can be achieved when their content is below 2.0wt.%.In the LPBF samples,the morphology of the CNTs is found to be directly related to their content.Especially,the length of CNTs in samples prepared by LPBF increases as the CNT content increases.The length of CNTs is approximately 200-300 nm in the 1.0wt.%CNTs/AlSi10Mg composites and approximately 500-1,000 nm in the 2.0wt.%CNTs/AlSi10Mg composites.The hardness of the composites reaches its highest value of 143.3 HV when the CNTs content is 1.0wt.%and the laser scan speed is 1,300 mm·s^(-1).It is found that the self-lubricating properties of the CNTs improve the tribological properties of the composites.The coefficient of friction(CoF)and wear rate of the samples decrease with increasing CNT content.At a CNTs content of 2.0wt.%,the CoF and wear rate of the composite decrease by approximately 14%and 30%,respectively,compared to the unreinforced matrix.The presence of CNTs leads to a more complete and refined network microstructure within the samples.Both the CNTs and the aluminum carbide contribute to the Orowan mechanism and the Hall-Petch effect within the matrix.展开更多
激光粉末床熔融(Laser Powder Bed Fusion,LPBF)是金属增材制造技术中的重要分支,具有个性化、自动化等优势。然而,在逐层制造过程中由于残余应力不断积累,易引发变形、断裂、疲劳等问题,限制了其进一步应用。为预测金属增材制造件的位...激光粉末床熔融(Laser Powder Bed Fusion,LPBF)是金属增材制造技术中的重要分支,具有个性化、自动化等优势。然而,在逐层制造过程中由于残余应力不断积累,易引发变形、断裂、疲劳等问题,限制了其进一步应用。为预测金属增材制造件的位移和残余应力,借助开源有限元求解代码JAX-FEM,开展基于热弹塑性本构模型的LPBF全尺寸热-力耦合数值模拟研究。其中,根据能量守恒定律确定等效激光功率、等效激光半径及扫描速度,简化计算模型、减少计算时间;通过修改制件底面的应力状态实现模拟制件从基板上切割分离的过程,并预测了应力释放的影响。分析扫描策略与速度对LPBF热-力耦合行为的影响,对比发现,采用水平Z形扫描策略相较于垂直扫描策略所产生的最大位移降低了24.0%,最大残余应力降低了13.6%;当扫描速度从0.8m/s增大到1.6m/s时,产生的最大位移降低了6.4%,最大残余应力降低了5.2%。该研究有助于为调控LPBF残余应力和变形提供科学指导。展开更多
Superelastic NiTi alloys produced through laser powder bed fusion(LPBF)hold great promise in advancing wear-resistant transmission devices for aerospace and related applications.However,limited research on their wear ...Superelastic NiTi alloys produced through laser powder bed fusion(LPBF)hold great promise in advancing wear-resistant transmission devices for aerospace and related applications.However,limited research on their wear behavior and strategies for enhancing wear resistance raises concerns about their future application prospects.In this study,a straightforward yet highly effective pre-strain treatment method is introduced,resulting in a nearly twofold improvement in the wear resistance of LPBF-fabricated NiTi alloys.This method prunes microstructure characteristics,influences the martensitic transformation process that improves cyclic compression superelasticity and transforms the distribution characteristics of adhesion stress acting on the indenter during wear processes,thereby effectively enhancing wear resistance.Additionally,the present study proposes an analytical model that establishes a link between superelastic metal cyclic compression characteristics and wear behaviors,providing insight into the wear characteristics,especially for adhesive wear patterns of superelastic metals including LPBF-fabricated NiTi alloys through analysis of cyclic compression curve.This research contributes to the fundamental understanding of wear resistance mechanisms in superelastic engineering materials and opens avenues for further optimization in related applications.展开更多
针对激光粉末床熔融(LPBF)传统合金三周期极小曲面(TPMS)点阵结构强塑性难以协同的难题,系统研究了Al Co Cr Fe Ni_(2.1)共晶高熵合金LPBF工艺及其TPMS点阵结构的力学性能。最优参数组合时Al Co Cr Fe Ni_(2.1)共晶高熵合金弹性模量达25...针对激光粉末床熔融(LPBF)传统合金三周期极小曲面(TPMS)点阵结构强塑性难以协同的难题,系统研究了Al Co Cr Fe Ni_(2.1)共晶高熵合金LPBF工艺及其TPMS点阵结构的力学性能。最优参数组合时Al Co Cr Fe Ni_(2.1)共晶高熵合金弹性模量达255 GPa,压缩屈服应力达1348 MPa,抗压强度达2520 MPa,压缩应变超25%。微观组织表征结果表明,其具有FCC(130~250 nm)/BCC(20~30 nm)双相纳米片层结构,元素偏聚形成异质界面协同强化。通过制造Diamond、Gyroid、Primitive三种TPMS结构及BCC桁架结构,揭示了点阵构型、相对密度和单胞尺寸结构参数对准静态压缩性能的影响规律。弹性模量、屈服应力及吸能均与相对密度正相关,Diamond、Gyroid和Primitive结构最大吸能分别达2369 J、2062 J和1096J。弹性模量与屈服应力随单胞尺寸增大呈线性增长,平台应力和吸能同步提升。Gyroid、Primitive结构在40%相对密度时比弹性模量的峰值分别达到47.8 GPa/kg、46.9 GPa/kg。相对Gyroid、Primitive、BCC构型,Diamond结构综合性能最优,比弹性模量达到72.6 GPa/kg,比吸能达38.7 J/g。与316L不锈钢和Ti-6Al-4V钛合金同类TPMS点阵综合对比,可知Al Co Cr Fe Ni_(2.1)点阵结构具有更为优异的强度-塑性匹配性能,在极端载荷条件下的高承载与吸能方面具有良好的应用前景。展开更多
现有GH4169镍基高温合金热处理制度设计主要基于传统铸造、锻造工艺,难以直接应用于增材制造。文章以激光粉末床熔融(Laser Powder Bed Fusion,LPBF)成形GH4169高温合金为研究对象,提出了均匀化+固溶+双时效、热等静压+固溶+双时效和真...现有GH4169镍基高温合金热处理制度设计主要基于传统铸造、锻造工艺,难以直接应用于增材制造。文章以激光粉末床熔融(Laser Powder Bed Fusion,LPBF)成形GH4169高温合金为研究对象,提出了均匀化+固溶+双时效、热等静压+固溶+双时效和真空热处理+固溶+双时效三种多重热处理制度,对比了三种制度对GH4169合金组织演变和高温力学性能的影响。研究表明,在第一步热处理的温度较低或降温速度较慢时,GH4169合金内部将产生具有粗大γ''相的深色晶粒;三种热处理制度制备的GH4169试样抗拉强度和屈服强度非常接近,而热等静压试样的断裂延伸率最高,在650℃、700℃和750℃分别达到23.7%、15.5%和12%,综合性能最优;在传统固溶+双时效热处理工艺前增加高温HIP处理,有利于提高合金的力学性能。文章为GH4169合金专用热处理制度的设计提供了可行的方案,对LPBF制造GH4169合金的进一步发展和应用,起到了促进作用。展开更多
激光粉末床熔融(Laser Powder Bed Fusion,LPBF)技术是定制化多孔纯Mo结构的重要技术。然而,LPBF成形纯Mo试样仍面临表面粗糙度值高及耐蚀性差等问题。电化学抛光(Electrochemical Polishing,ECP)是LPBF成形纯Mo的主要环保型后处理工艺...激光粉末床熔融(Laser Powder Bed Fusion,LPBF)技术是定制化多孔纯Mo结构的重要技术。然而,LPBF成形纯Mo试样仍面临表面粗糙度值高及耐蚀性差等问题。电化学抛光(Electrochemical Polishing,ECP)是LPBF成形纯Mo的主要环保型后处理工艺。研究了不同ECP抛光状态对LPBF成形纯Mo的表面粗糙度及降解特性的影响。结果表明:经电化学抛光处理后,试样表面粗糙度由4.55μm显著降低至1.05μm;相比原始态试样,抛光后试样腐蚀电流密度降低了78.4%。失重率从大到小顺序为:原始态>半抛光>抛光,且随着浸泡时间增加,失重率逐渐增加。溶液pH值波动≤0.5,验证了降解过程未引发局部酸化,符合生物医用材料要求。通过采用ECP处理Mo基材料表面,为合理调控其植入体的降解行为及降解速率的均匀性提供了重要理论依据。展开更多
Zn's natural degradability and biocompatibility make it a promising candidate for implants,however,its mechanical properties remain insufficient for bone applications.In this study,the performance of Zn was enhanc...Zn's natural degradability and biocompatibility make it a promising candidate for implants,however,its mechanical properties remain insufficient for bone applications.In this study,the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion(LPBF).Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed.Under optimized conditions of 100 W and 100 mm/s,high density(99.58%)Zn-Cu alloys with improved hardness(68.2 HV)and yield strength(160 MPa)were achieved.These improvements are attributed to solid solution strengthening,segregation strengthening,and grain refinement.The Zn-Cu alloys also demonstrated favorable degradation behavior,with a rate of 0.16 mm/year.This degradation is primarily driven by micro-galvanic corrosion between the CuZn 5 phase and Zn matrix,along with refined grains and increased grain boundary density.This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.展开更多
激光粉末床熔融(Laser powder bed fusion,LPBF)技术能够高精度制造复杂金属构件,其成形过程的质量波动与缺陷在线监测是目前研究的重点方向之一。本研究面向Ti-6Al-4V合金LPBF过程,构建了一种基于原位视觉感知的成形层形貌在线监测与...激光粉末床熔融(Laser powder bed fusion,LPBF)技术能够高精度制造复杂金属构件,其成形过程的质量波动与缺陷在线监测是目前研究的重点方向之一。本研究面向Ti-6Al-4V合金LPBF过程,构建了一种基于原位视觉感知的成形层形貌在线监测与分类识别方法,可实现对成形质量的预测。首先,通过单道熔道实验系统分析不同激光功率与扫描速度组合下的熔池行为及成形层光学形貌特征,将成形层形貌依据能量密度划分为低能区、适能区与高能区,为后续分类标注建立实验基准。随后开展9组不同工艺参数的成形实验,并采集逐层成形图像,表征成形质量,构建“工艺参数—成形层形貌—成形质量”之间的定量关联。基于采集的图像数据构建多模态增强数据集(包括几何增强、噪声注入与光照调整),并采用YOLOv5s模型学习成形层光学特征与能量输入状态之间的映射关系,实现对成形质量区间的在线识别与预测。实验结果表明,模型在100个Epoch训练后,可对高、中、低能量密度形貌的识别达到97%以上准确率(m AP>0.90)。研究揭示了成形工艺参数驱动下的成形质量与成形层光学形貌之间的对应关系,为LPBF过程质量在线监测与实时调控提供了可工程化的技术路径。展开更多
基金National Key Research and Development Program of China(2023YFB4606400)Supported by Longmen Laboratory Frontier Exploration Topics(LMQYTSKT003)。
文摘Copper manufactured by laser powder bed fusion(LPBF)process typically exhibits poor strength-ductility coordination,and the addition of strengthening phases is an effective way to address this issue.To explore the effects of strengthening phases on Cu,Cu-carbon nanotubes(CNTs)composites were prepared using LPBF technique with Cu-CNTs mixed powder as the matrix.The formability,microstructure,mechanical properties,electrical conductivity,and thermal properties were studied.The result shows that the prepared composites have high relative density.The addition of CNTs results in inhomogeneous equiaxed grains at the edges of the molten pool and columnar grains at the center.Compared with pure copper,the overall mechanical properties of the composite are improved:tensile strength increases by 52.8%and elongation increases by 146.4%;the electrical and thermal properties are also enhanced:thermal conductivity increases by 10.8%and electrical conductivity increases by 12.7%.
基金supported by the Natural Science Foundation of Jiangsu Higher Education Institutions of China(Grant No.23KJD460003)the Scientific Research Foundation for High-level Talents of Nanjing Institute of Technology(Grant No.YKJ202103)the National Natural Science Foundation of China(Grant Nos.92463301,92163215,52205471,52305470).
文摘In this study,carbon nanotubes(CNTs)/AlSi10Mg composite parts with CNTs contents ranging from 0.0 to 2.0wt.%were successfully fabricated via laser powder bed fusion(LPBF)with laser scan speeds ranging from 900 to 1,900 mm·s^(-1).Uniform dispersion of CNTs in the powders can be achieved when their content is below 2.0wt.%.In the LPBF samples,the morphology of the CNTs is found to be directly related to their content.Especially,the length of CNTs in samples prepared by LPBF increases as the CNT content increases.The length of CNTs is approximately 200-300 nm in the 1.0wt.%CNTs/AlSi10Mg composites and approximately 500-1,000 nm in the 2.0wt.%CNTs/AlSi10Mg composites.The hardness of the composites reaches its highest value of 143.3 HV when the CNTs content is 1.0wt.%and the laser scan speed is 1,300 mm·s^(-1).It is found that the self-lubricating properties of the CNTs improve the tribological properties of the composites.The coefficient of friction(CoF)and wear rate of the samples decrease with increasing CNT content.At a CNTs content of 2.0wt.%,the CoF and wear rate of the composite decrease by approximately 14%and 30%,respectively,compared to the unreinforced matrix.The presence of CNTs leads to a more complete and refined network microstructure within the samples.Both the CNTs and the aluminum carbide contribute to the Orowan mechanism and the Hall-Petch effect within the matrix.
文摘激光粉末床熔融(Laser Powder Bed Fusion,LPBF)是金属增材制造技术中的重要分支,具有个性化、自动化等优势。然而,在逐层制造过程中由于残余应力不断积累,易引发变形、断裂、疲劳等问题,限制了其进一步应用。为预测金属增材制造件的位移和残余应力,借助开源有限元求解代码JAX-FEM,开展基于热弹塑性本构模型的LPBF全尺寸热-力耦合数值模拟研究。其中,根据能量守恒定律确定等效激光功率、等效激光半径及扫描速度,简化计算模型、减少计算时间;通过修改制件底面的应力状态实现模拟制件从基板上切割分离的过程,并预测了应力释放的影响。分析扫描策略与速度对LPBF热-力耦合行为的影响,对比发现,采用水平Z形扫描策略相较于垂直扫描策略所产生的最大位移降低了24.0%,最大残余应力降低了13.6%;当扫描速度从0.8m/s增大到1.6m/s时,产生的最大位移降低了6.4%,最大残余应力降低了5.2%。该研究有助于为调控LPBF残余应力和变形提供科学指导。
基金supported by the National Natural Science Foundation of China(Nos.52025053 and 52235006)the National Key R&D Program of China(No.2022YFB4600500).
文摘Superelastic NiTi alloys produced through laser powder bed fusion(LPBF)hold great promise in advancing wear-resistant transmission devices for aerospace and related applications.However,limited research on their wear behavior and strategies for enhancing wear resistance raises concerns about their future application prospects.In this study,a straightforward yet highly effective pre-strain treatment method is introduced,resulting in a nearly twofold improvement in the wear resistance of LPBF-fabricated NiTi alloys.This method prunes microstructure characteristics,influences the martensitic transformation process that improves cyclic compression superelasticity and transforms the distribution characteristics of adhesion stress acting on the indenter during wear processes,thereby effectively enhancing wear resistance.Additionally,the present study proposes an analytical model that establishes a link between superelastic metal cyclic compression characteristics and wear behaviors,providing insight into the wear characteristics,especially for adhesive wear patterns of superelastic metals including LPBF-fabricated NiTi alloys through analysis of cyclic compression curve.This research contributes to the fundamental understanding of wear resistance mechanisms in superelastic engineering materials and opens avenues for further optimization in related applications.
文摘针对激光粉末床熔融(LPBF)传统合金三周期极小曲面(TPMS)点阵结构强塑性难以协同的难题,系统研究了Al Co Cr Fe Ni_(2.1)共晶高熵合金LPBF工艺及其TPMS点阵结构的力学性能。最优参数组合时Al Co Cr Fe Ni_(2.1)共晶高熵合金弹性模量达255 GPa,压缩屈服应力达1348 MPa,抗压强度达2520 MPa,压缩应变超25%。微观组织表征结果表明,其具有FCC(130~250 nm)/BCC(20~30 nm)双相纳米片层结构,元素偏聚形成异质界面协同强化。通过制造Diamond、Gyroid、Primitive三种TPMS结构及BCC桁架结构,揭示了点阵构型、相对密度和单胞尺寸结构参数对准静态压缩性能的影响规律。弹性模量、屈服应力及吸能均与相对密度正相关,Diamond、Gyroid和Primitive结构最大吸能分别达2369 J、2062 J和1096J。弹性模量与屈服应力随单胞尺寸增大呈线性增长,平台应力和吸能同步提升。Gyroid、Primitive结构在40%相对密度时比弹性模量的峰值分别达到47.8 GPa/kg、46.9 GPa/kg。相对Gyroid、Primitive、BCC构型,Diamond结构综合性能最优,比弹性模量达到72.6 GPa/kg,比吸能达38.7 J/g。与316L不锈钢和Ti-6Al-4V钛合金同类TPMS点阵综合对比,可知Al Co Cr Fe Ni_(2.1)点阵结构具有更为优异的强度-塑性匹配性能,在极端载荷条件下的高承载与吸能方面具有良好的应用前景。
文摘现有GH4169镍基高温合金热处理制度设计主要基于传统铸造、锻造工艺,难以直接应用于增材制造。文章以激光粉末床熔融(Laser Powder Bed Fusion,LPBF)成形GH4169高温合金为研究对象,提出了均匀化+固溶+双时效、热等静压+固溶+双时效和真空热处理+固溶+双时效三种多重热处理制度,对比了三种制度对GH4169合金组织演变和高温力学性能的影响。研究表明,在第一步热处理的温度较低或降温速度较慢时,GH4169合金内部将产生具有粗大γ''相的深色晶粒;三种热处理制度制备的GH4169试样抗拉强度和屈服强度非常接近,而热等静压试样的断裂延伸率最高,在650℃、700℃和750℃分别达到23.7%、15.5%和12%,综合性能最优;在传统固溶+双时效热处理工艺前增加高温HIP处理,有利于提高合金的力学性能。文章为GH4169合金专用热处理制度的设计提供了可行的方案,对LPBF制造GH4169合金的进一步发展和应用,起到了促进作用。
文摘激光粉末床熔融(Laser Powder Bed Fusion,LPBF)技术是定制化多孔纯Mo结构的重要技术。然而,LPBF成形纯Mo试样仍面临表面粗糙度值高及耐蚀性差等问题。电化学抛光(Electrochemical Polishing,ECP)是LPBF成形纯Mo的主要环保型后处理工艺。研究了不同ECP抛光状态对LPBF成形纯Mo的表面粗糙度及降解特性的影响。结果表明:经电化学抛光处理后,试样表面粗糙度由4.55μm显著降低至1.05μm;相比原始态试样,抛光后试样腐蚀电流密度降低了78.4%。失重率从大到小顺序为:原始态>半抛光>抛光,且随着浸泡时间增加,失重率逐渐增加。溶液pH值波动≤0.5,验证了降解过程未引发局部酸化,符合生物医用材料要求。通过采用ECP处理Mo基材料表面,为合理调控其植入体的降解行为及降解速率的均匀性提供了重要理论依据。
基金Projects(52571276,52275395,U24A20120,52475362)supported by the National Natural Science Foundation of ChinaProject(2025JJ30015)supported by the Hunan Provincial Natural Science Foundation,China+3 种基金Project(2023RC3046)supported by the Science and Technology Innovation Program of Hunan Province,ChinaProject(2023YFB4605800)supported by National Key Research and Development Program of ChinaProject(2023CXQD023)supported by the Central South University Innovation-Driven Research Programme,ChinaProject supported by the State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University,China。
文摘Zn's natural degradability and biocompatibility make it a promising candidate for implants,however,its mechanical properties remain insufficient for bone applications.In this study,the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion(LPBF).Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed.Under optimized conditions of 100 W and 100 mm/s,high density(99.58%)Zn-Cu alloys with improved hardness(68.2 HV)and yield strength(160 MPa)were achieved.These improvements are attributed to solid solution strengthening,segregation strengthening,and grain refinement.The Zn-Cu alloys also demonstrated favorable degradation behavior,with a rate of 0.16 mm/year.This degradation is primarily driven by micro-galvanic corrosion between the CuZn 5 phase and Zn matrix,along with refined grains and increased grain boundary density.This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.
文摘激光粉末床熔融(Laser powder bed fusion,LPBF)技术能够高精度制造复杂金属构件,其成形过程的质量波动与缺陷在线监测是目前研究的重点方向之一。本研究面向Ti-6Al-4V合金LPBF过程,构建了一种基于原位视觉感知的成形层形貌在线监测与分类识别方法,可实现对成形质量的预测。首先,通过单道熔道实验系统分析不同激光功率与扫描速度组合下的熔池行为及成形层光学形貌特征,将成形层形貌依据能量密度划分为低能区、适能区与高能区,为后续分类标注建立实验基准。随后开展9组不同工艺参数的成形实验,并采集逐层成形图像,表征成形质量,构建“工艺参数—成形层形貌—成形质量”之间的定量关联。基于采集的图像数据构建多模态增强数据集(包括几何增强、噪声注入与光照调整),并采用YOLOv5s模型学习成形层光学特征与能量输入状态之间的映射关系,实现对成形质量区间的在线识别与预测。实验结果表明,模型在100个Epoch训练后,可对高、中、低能量密度形貌的识别达到97%以上准确率(m AP>0.90)。研究揭示了成形工艺参数驱动下的成形质量与成形层光学形貌之间的对应关系,为LPBF过程质量在线监测与实时调控提供了可工程化的技术路径。
