The anisotropy of the structure and properties caused by the strong epitaxial growth of grains during laser powder bed fusion(L-PBF)significantly affects the mechanical performance of Inconel 718 alloy components such...The anisotropy of the structure and properties caused by the strong epitaxial growth of grains during laser powder bed fusion(L-PBF)significantly affects the mechanical performance of Inconel 718 alloy components such as turbine disks.The defects(lack-of-fusion Lo F)in components processed via L-PBF are detrimental to the strength of the alloy.The purpose of this study is to investigate the effect of laser scanning parameters on the epitaxial grain growth and LoF formation in order to obtain the parameter space in which the microstructure is refined and LoF defect is suppressed.The temperature field of the molten pool and the epitaxial grain growth are simulated using a multiscale model combining the finite element method with the phase-field method.The LoF model is proposed to predict the formation of LoF defects resulting from insufficient melting during L-PBF.Defect mitigation and grain-structure control during L-PBF can be realized simultaneously in the model.The simulation shows the input laser energy density for the as-deposited structure with fine grains and without LoF defects varied from 55.0–62.5 J·mm^(-3)when the interlayer rotation angle was 0°–90°.The optimized process parameters(laser power of 280 W,scanning speed of 1160 mm·s^(-1),and rotation angle of 67°)were computationally screened.In these conditions,the average grain size was 7.0μm,and the ultimate tensile strength and yield strength at room temperature were(1111±3)MPa and(820±7)MPa,respectively,which is 8.8%and10.5%higher than those of reported.The results indicating the proposed multiscale computational approach for predicting grain growth and Lo F defects could allow simultaneous grain-structure control and defect mitigation during L-PBF.展开更多
The original online version of this article unfortunately contained a mistake.The reference[24]in the original online version is incorrect.The correct version is given below:Y.H.Cheng,Numerical Simulation and Experime...The original online version of this article unfortunately contained a mistake.The reference[24]in the original online version is incorrect.The correct version is given below:Y.H.Cheng,Numerical Simulation and Experimental Research of Selective Laser Melting on Nickel Based Alloy Powder GH4169[Dissertation],North University of China,Taiyuan,2016.展开更多
In this study,an overcasting process followed by a low-temperature(200°C)annealing schedule has been developed to bond magnesium to aluminum alloys.ProCAST software was used to optimize the process parameters dur...In this study,an overcasting process followed by a low-temperature(200°C)annealing schedule has been developed to bond magnesium to aluminum alloys.ProCAST software was used to optimize the process parameters during the overcasting process which lead to Mg/Al bimetallic structures to be successfully produced without formation of Mg-Al intermetallic phases.Detailed microstructure evolution during annealing,including the formation and growth of Al-Mg interdiffusion layer and intermetallic phases(Al12Mg17 and Al3Mg2),was experimentally observed for the first time with direct evidence,and predicted using Calculation of Phase Diagrams(CALPHAD)modeling.Maximum interfacial strength was achieved when the interdiffusion layer formed at the Mg/Al interface reached a maximum thickness the without formation of brittle intermetallic compounds.The precise diffusion modeling of the Mg/Al interface provides an efficient way to optimize and control the interfacial microstructure of Mg/Al bimetallic structures for improved interfacial bonding.展开更多
In this work,nonisothermal dissolution of intermetallic Mg_(17)Al_(12) in Mg-Al alloy has been firstly studied via Differential Scanning Calorimetry-DSC,X-Ray Diffraction-XRD and Scanning Electron Microscope-SEM as we...In this work,nonisothermal dissolution of intermetallic Mg_(17)Al_(12) in Mg-Al alloy has been firstly studied via Differential Scanning Calorimetry-DSC,X-Ray Diffraction-XRD and Scanning Electron Microscope-SEM as well as CALPHAD_based dissolution models and molecular dynamics simulation.The size and volume fraction of Mg_(17)Al_(12) phase could be predicted via the present kinetic dissolution model and agree well with experimental results.Also,the data-driven screening calculation shows that there is a range of temperature for significantly dissolving Mg_(17)Al_(12) phase,which could be increased with the increase of heating rate.The evolution of structural order for Mg_(17)Al_(12) phase has also been performed via molecular dynamics simulation with LAMMPS.The simulated results indicate that the structural order of Mg_(17)Al_(12) phase during heating is mainly affected by the Al-contained atomic pairs(Al-Al and Al-Mg),suggested that Mg atoms are thermodynamically and kinetically more active than Al atoms in Mg_(17)Al_(12) phase during heating,which has also been approved via the calculated atomic mobility of Mg and Al atoms in Mg_(17)Al_(12) phase in this work.Therefore,the atomic mobility of Mg atoms is mainly attributed to the interdiffusion coefficient of Mg_(17)Al_(12) phase which determines the dissolution of Mg_(17)Al_(12) phase during heating.The fundamental principle in this work could be used for other intermetallics and offers the greatly valuable information for optimizing the thermal processing in application of metal structural materials.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFB 3700701)the National Natural Science Foundation of China(Nos.52090041,52022011)+1 种基金the National Major Science and Technology Projects of China(No.J2019-VI-00090123)the Key-area Research and Development Program of Guangdong Province(No.2019b010943001)。
文摘The anisotropy of the structure and properties caused by the strong epitaxial growth of grains during laser powder bed fusion(L-PBF)significantly affects the mechanical performance of Inconel 718 alloy components such as turbine disks.The defects(lack-of-fusion Lo F)in components processed via L-PBF are detrimental to the strength of the alloy.The purpose of this study is to investigate the effect of laser scanning parameters on the epitaxial grain growth and LoF formation in order to obtain the parameter space in which the microstructure is refined and LoF defect is suppressed.The temperature field of the molten pool and the epitaxial grain growth are simulated using a multiscale model combining the finite element method with the phase-field method.The LoF model is proposed to predict the formation of LoF defects resulting from insufficient melting during L-PBF.Defect mitigation and grain-structure control during L-PBF can be realized simultaneously in the model.The simulation shows the input laser energy density for the as-deposited structure with fine grains and without LoF defects varied from 55.0–62.5 J·mm^(-3)when the interlayer rotation angle was 0°–90°.The optimized process parameters(laser power of 280 W,scanning speed of 1160 mm·s^(-1),and rotation angle of 67°)were computationally screened.In these conditions,the average grain size was 7.0μm,and the ultimate tensile strength and yield strength at room temperature were(1111±3)MPa and(820±7)MPa,respectively,which is 8.8%and10.5%higher than those of reported.The results indicating the proposed multiscale computational approach for predicting grain growth and Lo F defects could allow simultaneous grain-structure control and defect mitigation during L-PBF.
文摘The original online version of this article unfortunately contained a mistake.The reference[24]in the original online version is incorrect.The correct version is given below:Y.H.Cheng,Numerical Simulation and Experimental Research of Selective Laser Melting on Nickel Based Alloy Powder GH4169[Dissertation],North University of China,Taiyuan,2016.
基金the National Natural Science Foundation of China[grant number 51571080].
文摘In this study,an overcasting process followed by a low-temperature(200°C)annealing schedule has been developed to bond magnesium to aluminum alloys.ProCAST software was used to optimize the process parameters during the overcasting process which lead to Mg/Al bimetallic structures to be successfully produced without formation of Mg-Al intermetallic phases.Detailed microstructure evolution during annealing,including the formation and growth of Al-Mg interdiffusion layer and intermetallic phases(Al12Mg17 and Al3Mg2),was experimentally observed for the first time with direct evidence,and predicted using Calculation of Phase Diagrams(CALPHAD)modeling.Maximum interfacial strength was achieved when the interdiffusion layer formed at the Mg/Al interface reached a maximum thickness the without formation of brittle intermetallic compounds.The precise diffusion modeling of the Mg/Al interface provides an efficient way to optimize and control the interfacial microstructure of Mg/Al bimetallic structures for improved interfacial bonding.
基金support from Fundamental Research Funds for the Central Universities under Award Number 06500161。
文摘In this work,nonisothermal dissolution of intermetallic Mg_(17)Al_(12) in Mg-Al alloy has been firstly studied via Differential Scanning Calorimetry-DSC,X-Ray Diffraction-XRD and Scanning Electron Microscope-SEM as well as CALPHAD_based dissolution models and molecular dynamics simulation.The size and volume fraction of Mg_(17)Al_(12) phase could be predicted via the present kinetic dissolution model and agree well with experimental results.Also,the data-driven screening calculation shows that there is a range of temperature for significantly dissolving Mg_(17)Al_(12) phase,which could be increased with the increase of heating rate.The evolution of structural order for Mg_(17)Al_(12) phase has also been performed via molecular dynamics simulation with LAMMPS.The simulated results indicate that the structural order of Mg_(17)Al_(12) phase during heating is mainly affected by the Al-contained atomic pairs(Al-Al and Al-Mg),suggested that Mg atoms are thermodynamically and kinetically more active than Al atoms in Mg_(17)Al_(12) phase during heating,which has also been approved via the calculated atomic mobility of Mg and Al atoms in Mg_(17)Al_(12) phase in this work.Therefore,the atomic mobility of Mg atoms is mainly attributed to the interdiffusion coefficient of Mg_(17)Al_(12) phase which determines the dissolution of Mg_(17)Al_(12) phase during heating.The fundamental principle in this work could be used for other intermetallics and offers the greatly valuable information for optimizing the thermal processing in application of metal structural materials.