Laser powder bed fusion(LPBF)additive manufacturing of zinc(Zn)offers promising advantages for biodegradable metal bone implants,including tailorable microstructures,controllable porous structures,and appropriate degr...Laser powder bed fusion(LPBF)additive manufacturing of zinc(Zn)offers promising advantages for biodegradable metal bone implants,including tailorable microstructures,controllable porous structures,and appropriate degradation rates.However,the layer-by-layer construction during LPBF often leads to microstructural and performance anisotropy within metallic materials.In this work,the anisotropic mechanical and degradation properties of pure Zn processed using LPBF were comprehensively investigated for the first time.Specifically,the influence of microstructural characteristics on the mechanical and degradation properties of LPBF-processed Zn in both horizontal and vertical planes was revealed,while the underlying deformation mechanisms in different planes were illustrated.The results demonstrated that the horizontal plane exhibited higher mechanical strength compared to the vertical plane,with ulti-mate tensile strength of 123.6 and 107.86 MPa,respectively,significantly surpassing that of the tradition-ally cast counterpart(52.7 MPa).Importantly,abundant deformation twins coupled with infrequent microbands and pyramidal(c+a)slip systems activated during tensile loading along the vertical plane enabled multiple deformation modes,which sustained durable work hardening ability while delaying plastic instability,resulting in extraordinary plasticity(elongation of 14.2%).Additionally,synergistic effects between high-density grain boundaries including low-angle grain boundaries and pre-existing dislocations promoted the stable presence of a passive film along the horizontal plane,thus exhibiting relatively low corrosion sensitivity.Furthermore,the LPBF-processed Zn also demonstrated favorable biological activity and osteogenic potential.These findings provide valuable insights into multiple mechanisms underlying anisotropy in mechanical and degradation properties of laser additively manufactured Zn-based materials.展开更多
Multi-material laser powder bed fusion(LPBF)additive manufacturing is a promising approach for integrating the functionality and mechanical performance of dissimilar materials into complex parts.This review offers a c...Multi-material laser powder bed fusion(LPBF)additive manufacturing is a promising approach for integrating the functionality and mechanical performance of dissimilar materials into complex parts.This review offers a comprehensive overview of the recent advancements in multi-material LPBF,with a particular focus on compositionally heterogeneous/gradient parts and their fabrication methods and equipment,control of interfacial defects,innovative designs,and potential applications.It commences with the introduction of LPBF-processed compositionally heterogeneous/gradient structures with dissimilar material distributions,including Z-direction compositionally heterogeneous structures,compositionally gradient structures in the Z-direction and XY planes,and three-dimensional(3D)compositionally heterogeneous structures.Subsequently,various LPBF methods and equipment for fabricating compositionally heterogeneous/gradient structures have been presented.Furthermore,the interfacial defects and process control during LPBF for these types of compositionally heterogeneous/gradient structures are discussed.Additionally,innovative designs and potential applications of parts made from compositionally heterogeneous/gradient structures are illustrated.Finally,perspectives on the LPBF fabrication methods for compositionally heterogeneous/gradient structures are highlighted to provide guidance for future research.展开更多
Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturin...Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturing was employed to fabricate pure Zn with a heterogeneous microstructure and exceptional strength-ductility synergy.An optimized processing window of LPBF was established for printing Zn samples with relative densities greater than 99%using a laser power range of 80∼90 W and a scanning speed of 900 mm s−1.The Zn sample printed with a power of 80 W at a speed of 900 mm s−1 exhibited a hierarchical heterogeneous microstructure consisting of millimeter-scale molten pool boundaries,micrometer-scale bimodal grains,and nanometer-scale pre-existing dislocations,due to rapid cooling rates and significant thermal gradients formed in the molten pools.The printed sample exhibited the highest ductility of∼12.1%among all reported LPBF-printed pure Zn to date with appreciable ultimate tensile strength(∼128.7 MPa).Such superior strength-ductility synergy can be attributed to the presence of multiple deformation mechanisms that are primarily governed by heterogeneous deformation-induced hardening resulting from the alternative arrangement of bimodal Zn grains with pre-existing dislocations.Additionally,continuous strain hardening was facilitated through the interactions between deformation twins,grains and dislocations as strain accumulated,further contributing to the superior strength-ductility synergy.These findings provide valuable insights into the deformation behavior and mechanisms underlying exceptional mechanical properties of LPBF-printed Zn and its alloys for implant applications.展开更多
Laser additive manufacturing(LAM)technology can overcome the limitations of conventional manufacturing and facilitate the integrated design and production of geometrically complex metal parts,making it widely applicab...Laser additive manufacturing(LAM)technology can overcome the limitations of conventional manufacturing and facilitate the integrated design and production of geometrically complex metal parts,making it widely applicable in industrial sectors such as biomedical,aerospace,and molding.This review provides an overview of the frontiers of LAM techniques,focusing on the progress made by our research group over the past two decades.It begins with the introduction of four critical types of advanced LAM techniques:large-scale,multimaterial,field-assisted,and LAM/subtractive hybrid manufacturing.Subsequently,coaxial and off-axial in situ monitoring techniques based on sensor installation are presented,along with an exploration of their integration with high-speed cameras,photodiodes,and other photoelectric sensors within the LAM equipment.Representative innovative designs incorporating small-angle and support-free structures,nonassembled structures,and porous structures are then introduced.Finally,a comprehensive summary is provided,along with a discussion of the development trends of LAM from both manufacturing and design perspectives.展开更多
This paper mainly studies the method of dynamic embedded Web server technology and its realization. Taking S3C2440 processor as the core hardware platform, constructed the software system of based on Linux operating s...This paper mainly studies the method of dynamic embedded Web server technology and its realization. Taking S3C2440 processor as the core hardware platform, constructed the software system of based on Linux operating system on the hardware platform; Analysis the key technology of web server, select Boa as the embedded web server, Boa server and CGIC database successfully transplanted and run the static Webpage： The paper detailed analysis of the CGI technology and using C language to compile the CGI program to realize dynamic Web server, realize the use of the Web browser to the remote Web server access control function.展开更多
Additive manufacturing of Al-Mg-Sc-Zr alloys is a promising technique for the fabrication of lightweight components with complex shapes.In this study,the effect of the process parameters of selective laser melting(SLM...Additive manufacturing of Al-Mg-Sc-Zr alloys is a promising technique for the fabrication of lightweight components with complex shapes.In this study,the effect of the process parameters of selective laser melting(SLM)on the surface morphology,relative density,microstructure,and mechanical properties of Al-Mg-Sc-Zr high-strength aluminum alloys with low Sc content was systematically investigated.The results show that the energy density has an important effect on the surface quality and densification behavior of the Al-Mg-Sc-Zr alloy during the SLM process.As the energy density increased,the surface quality and the number of internal pores increased.However,the area of the fine-grained region at the boundary of the molten pool gradually decreased.When the laser energy density was set to 151.52 J/mm3,a low-defect sample with a relative density of 99.2%was obtained.After heat treatment,the area of the fine grains at the boundary increased significantly,thereby contributing to the excellent mechanical properties.The microstructure was characterized by a unique“fan-shaped”heterogeneous structure.As the energy density increased,the microhardness first increased and then decreased,reaching a maximum value of 122 HV0.3.With the optimized process parameters,the yield strength(YS),ultimate tensile strength(UTS),and elongation of the as-built Al-Mg-Sc-Zr alloys were 346.8±3.0 MPa,451.1±5.2 MPa,14.6%±0.8%,respectively.After heat treatment at 325°C for 8 h,the hardness increased by 38.5%to 169 HV0.3,and the YS and UTS increased by 41.3%and 18.1%,respectively,to 490.0±9.0 MPa and 532.7±7.8 MPa,respectively,while the elongation slightly decreased to 13.1%±0.7%.展开更多
Determining appropriate process parameters in large-scale laser powder bed fusion(LPBF)additive manufacturing pose formidable challenges that necessitate advanced approaches to minimize trial-and-error during experime...Determining appropriate process parameters in large-scale laser powder bed fusion(LPBF)additive manufacturing pose formidable challenges that necessitate advanced approaches to minimize trial-and-error during experimentation.This work proposed a data-driven approach based on stacking ensemble learning to predict the mechanical properties of Ti6Al4V alloy fabricated by large-scale LPBF for the first time.This method can adapt to the complexity of large-scale LPBF data distribution and exhibits a more generalized predictive capability compared to base models.Specifically,the stacking model utilized artificial neural network(ANN),gradient boosting regressor,kernel ridge regression,and elastic net as base models,with the Lasso model serving as the meta-model.Bayesian optimization and cross-validation were utilized for model optimization and training based on a limited data set,resulting in higher predictive accuracy compared to traditional artificial neural network model.The statistical analysis of the ANN and stacking models indicates that the stacking model exhibits superior performance on the test set,with a coefficient of determination value of 0.944,mean absolute percentage error of 2.51%,and root mean squared error of 27.64,surpassing that of the ANN model.All statistical metrics demonstrate superiority over those obtained from the ANN model.These results confirm that by integrating the base models,the stacking model exhibits superior predictive stability compared to individual base models alone,thereby providing a reliable assessment approach for predicting the mechanical properties of metal parts fabricated by the LPBF process.展开更多
基金supported by the following funds:the National Natural Science Foundation of China(No.52305358)the Fundamental Research Funds for the Central Universities(No.2023ZYGXZR061)+2 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2022A1515010304)the Young Elite Scientists Sponsorship Program by CAST(No.2023QNRC001)the Young Talent Support Project of Guangzhou(No.QT-2023-001).
文摘Laser powder bed fusion(LPBF)additive manufacturing of zinc(Zn)offers promising advantages for biodegradable metal bone implants,including tailorable microstructures,controllable porous structures,and appropriate degradation rates.However,the layer-by-layer construction during LPBF often leads to microstructural and performance anisotropy within metallic materials.In this work,the anisotropic mechanical and degradation properties of pure Zn processed using LPBF were comprehensively investigated for the first time.Specifically,the influence of microstructural characteristics on the mechanical and degradation properties of LPBF-processed Zn in both horizontal and vertical planes was revealed,while the underlying deformation mechanisms in different planes were illustrated.The results demonstrated that the horizontal plane exhibited higher mechanical strength compared to the vertical plane,with ulti-mate tensile strength of 123.6 and 107.86 MPa,respectively,significantly surpassing that of the tradition-ally cast counterpart(52.7 MPa).Importantly,abundant deformation twins coupled with infrequent microbands and pyramidal(c+a)slip systems activated during tensile loading along the vertical plane enabled multiple deformation modes,which sustained durable work hardening ability while delaying plastic instability,resulting in extraordinary plasticity(elongation of 14.2%).Additionally,synergistic effects between high-density grain boundaries including low-angle grain boundaries and pre-existing dislocations promoted the stable presence of a passive film along the horizontal plane,thus exhibiting relatively low corrosion sensitivity.Furthermore,the LPBF-processed Zn also demonstrated favorable biological activity and osteogenic potential.These findings provide valuable insights into multiple mechanisms underlying anisotropy in mechanical and degradation properties of laser additively manufactured Zn-based materials.
基金supported by the following projects:the National Key Research and Development Program of China(Nos.2022YFB4600303,and 2024YFB4608200)Guangdong Basic and Applied Basic Research Foundation(Nos.2022B1515020064,and 2022B1515120025)+2 种基金National Natural Science Foundation of China(Nos.52073105,and 52305358)the Fundamental Research Funds for the Central Universities(2024ZYGXZR079)Young Elite Scientists Sponsorship Program by CAST(2023QNRC001)。
文摘Multi-material laser powder bed fusion(LPBF)additive manufacturing is a promising approach for integrating the functionality and mechanical performance of dissimilar materials into complex parts.This review offers a comprehensive overview of the recent advancements in multi-material LPBF,with a particular focus on compositionally heterogeneous/gradient parts and their fabrication methods and equipment,control of interfacial defects,innovative designs,and potential applications.It commences with the introduction of LPBF-processed compositionally heterogeneous/gradient structures with dissimilar material distributions,including Z-direction compositionally heterogeneous structures,compositionally gradient structures in the Z-direction and XY planes,and three-dimensional(3D)compositionally heterogeneous structures.Subsequently,various LPBF methods and equipment for fabricating compositionally heterogeneous/gradient structures have been presented.Furthermore,the interfacial defects and process control during LPBF for these types of compositionally heterogeneous/gradient structures are discussed.Additionally,innovative designs and potential applications of parts made from compositionally heterogeneous/gradient structures are illustrated.Finally,perspectives on the LPBF fabrication methods for compositionally heterogeneous/gradient structures are highlighted to provide guidance for future research.
基金National Natural Science Foundation of China (52305358)the Fundamental Research Funds for the Central Universities (2023ZYGXZR061)+3 种基金Guangdong Basic and Applied Basic Research Foundation (2022A1515010304)Science and Technology Program of Guangzhou (202201010362)Young Elite Scientists Sponsorship Program by CAST . (2023QNRC001)Young Talent Support Project of Guangzhou (QT-2023-001)
文摘Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturing was employed to fabricate pure Zn with a heterogeneous microstructure and exceptional strength-ductility synergy.An optimized processing window of LPBF was established for printing Zn samples with relative densities greater than 99%using a laser power range of 80∼90 W and a scanning speed of 900 mm s−1.The Zn sample printed with a power of 80 W at a speed of 900 mm s−1 exhibited a hierarchical heterogeneous microstructure consisting of millimeter-scale molten pool boundaries,micrometer-scale bimodal grains,and nanometer-scale pre-existing dislocations,due to rapid cooling rates and significant thermal gradients formed in the molten pools.The printed sample exhibited the highest ductility of∼12.1%among all reported LPBF-printed pure Zn to date with appreciable ultimate tensile strength(∼128.7 MPa).Such superior strength-ductility synergy can be attributed to the presence of multiple deformation mechanisms that are primarily governed by heterogeneous deformation-induced hardening resulting from the alternative arrangement of bimodal Zn grains with pre-existing dislocations.Additionally,continuous strain hardening was facilitated through the interactions between deformation twins,grains and dislocations as strain accumulated,further contributing to the superior strength-ductility synergy.These findings provide valuable insights into the deformation behavior and mechanisms underlying exceptional mechanical properties of LPBF-printed Zn and its alloys for implant applications.
基金supported by National Key R&D Program of China(Grant No.2022YFF0606000)National Natural Science Foundation of China(Grant No.U2001218)Guangdong Basic and Applied Basic Research Foundation(Grant No.2022B1515020064).
文摘Laser additive manufacturing(LAM)technology can overcome the limitations of conventional manufacturing and facilitate the integrated design and production of geometrically complex metal parts,making it widely applicable in industrial sectors such as biomedical,aerospace,and molding.This review provides an overview of the frontiers of LAM techniques,focusing on the progress made by our research group over the past two decades.It begins with the introduction of four critical types of advanced LAM techniques:large-scale,multimaterial,field-assisted,and LAM/subtractive hybrid manufacturing.Subsequently,coaxial and off-axial in situ monitoring techniques based on sensor installation are presented,along with an exploration of their integration with high-speed cameras,photodiodes,and other photoelectric sensors within the LAM equipment.Representative innovative designs incorporating small-angle and support-free structures,nonassembled structures,and porous structures are then introduced.Finally,a comprehensive summary is provided,along with a discussion of the development trends of LAM from both manufacturing and design perspectives.
文摘This paper mainly studies the method of dynamic embedded Web server technology and its realization. Taking S3C2440 processor as the core hardware platform, constructed the software system of based on Linux operating system on the hardware platform; Analysis the key technology of web server, select Boa as the embedded web server, Boa server and CGIC database successfully transplanted and run the static Webpage： The paper detailed analysis of the CGI technology and using C language to compile the CGI program to realize dynamic Web server, realize the use of the Web browser to the remote Web server access control function.
基金Guangdong Provincial Key Field Research and Development Program Project of China(Grant No.2020B090922002)Guangdong Provincial Basic and Applied Basic Research Fund Project of China(Grant Nos.2019B1515120094,2022B1515020064)National Natural and Science Foundation of China(Grant No.51775196).
文摘Additive manufacturing of Al-Mg-Sc-Zr alloys is a promising technique for the fabrication of lightweight components with complex shapes.In this study,the effect of the process parameters of selective laser melting(SLM)on the surface morphology,relative density,microstructure,and mechanical properties of Al-Mg-Sc-Zr high-strength aluminum alloys with low Sc content was systematically investigated.The results show that the energy density has an important effect on the surface quality and densification behavior of the Al-Mg-Sc-Zr alloy during the SLM process.As the energy density increased,the surface quality and the number of internal pores increased.However,the area of the fine-grained region at the boundary of the molten pool gradually decreased.When the laser energy density was set to 151.52 J/mm3,a low-defect sample with a relative density of 99.2%was obtained.After heat treatment,the area of the fine grains at the boundary increased significantly,thereby contributing to the excellent mechanical properties.The microstructure was characterized by a unique“fan-shaped”heterogeneous structure.As the energy density increased,the microhardness first increased and then decreased,reaching a maximum value of 122 HV0.3.With the optimized process parameters,the yield strength(YS),ultimate tensile strength(UTS),and elongation of the as-built Al-Mg-Sc-Zr alloys were 346.8±3.0 MPa,451.1±5.2 MPa,14.6%±0.8%,respectively.After heat treatment at 325°C for 8 h,the hardness increased by 38.5%to 169 HV0.3,and the YS and UTS increased by 41.3%and 18.1%,respectively,to 490.0±9.0 MPa and 532.7±7.8 MPa,respectively,while the elongation slightly decreased to 13.1%±0.7%.
基金supported by the National Natural Science Foundation of China(Grant No.52305358)the Fundamental Research Funds for the Central Universities,China(Grant No.2023ZYGXZR061)+2 种基金the Guangdong Basic and Applied Basic Research Foundation,China(Grant No.2022A1515010304)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology,China(Grant No.2023QNRC001)the Young Talent Support Project of Guangzhou,China(Grant No.QT-2023-001).
文摘Determining appropriate process parameters in large-scale laser powder bed fusion(LPBF)additive manufacturing pose formidable challenges that necessitate advanced approaches to minimize trial-and-error during experimentation.This work proposed a data-driven approach based on stacking ensemble learning to predict the mechanical properties of Ti6Al4V alloy fabricated by large-scale LPBF for the first time.This method can adapt to the complexity of large-scale LPBF data distribution and exhibits a more generalized predictive capability compared to base models.Specifically,the stacking model utilized artificial neural network(ANN),gradient boosting regressor,kernel ridge regression,and elastic net as base models,with the Lasso model serving as the meta-model.Bayesian optimization and cross-validation were utilized for model optimization and training based on a limited data set,resulting in higher predictive accuracy compared to traditional artificial neural network model.The statistical analysis of the ANN and stacking models indicates that the stacking model exhibits superior performance on the test set,with a coefficient of determination value of 0.944,mean absolute percentage error of 2.51%,and root mean squared error of 27.64,surpassing that of the ANN model.All statistical metrics demonstrate superiority over those obtained from the ANN model.These results confirm that by integrating the base models,the stacking model exhibits superior predictive stability compared to individual base models alone,thereby providing a reliable assessment approach for predicting the mechanical properties of metal parts fabricated by the LPBF process.
