Grain size and texture can be controlled to improve the strength and ductility of magnesium rare-earth(Mg-RE)alloys by alloying.Directed energy deposition-arc(DED-arc)is a typical sub-rapid solidification process that...Grain size and texture can be controlled to improve the strength and ductility of magnesium rare-earth(Mg-RE)alloys by alloying.Directed energy deposition-arc(DED-arc)is a typical sub-rapid solidification process that contributes to the modification of the microstructure.In this paper,a series of novel Mg-3.0Nd-0.2Zn-0.3Zr-xCe(NZ30K-xCe)alloys with different Ce contents(0,0.1,0.3,0.5 wt.%)were prepared by DED-arc.The results show that the experimental alloys have lower porosity(≤0.11%).After adding 0.1 wt.%Ce,the average grain size decreases from 98.9±5.7μm to 49.8±1.0μm,and the texture is significantly weakened.Further additions of Ce(0.3 and 0.5 wt.%)do not lead to significant alterations in the average grain size and texture intensity when compared with the NZ30K-0.1Ce alloy.Grain refinement is related to the constitutional supercooling,and the texture weakening is connected to the solid solubility of Ce in the Mg matrix.The ultimate tensile strength and elongation of NZ30K-0.1Ce alloy are 37.2% and 61.3% higher than those of NZ30K alloy.Grain refinement and texture weakening are the reasons for the better strength-ductility of NZ30K-0.1Ce alloy.展开更多
In this study,the efects of diferent heat treatment process parameters on the microstructure and mechanical properties of Al-12Si-5Cu-1.1Mg-2.3Ni-0.3La alloy were explored.Research showed that eutectic Si underwent th...In this study,the efects of diferent heat treatment process parameters on the microstructure and mechanical properties of Al-12Si-5Cu-1.1Mg-2.3Ni-0.3La alloy were explored.Research showed that eutectic Si underwent three stages during solution treatment:difusing,spheroidization and coarsening.As the solution temperature and time increased,the size of eutectic Si showed a trend of frst decreasing and then increasing.Compared with the heat treatment time,the heat treatment temperature had a more signifcant efect on the mechanical properties.The coarsening of microstructure was the main reason for the deterioration of mechanical properties.The Al_(3)Ti and Al_(3)CuNiLa in the microstructure after aging can signifcantly improve the mechanical properties of the alloy.The Al_(11)La_(3) with secondary precipitation occurred in the La-rich phase.The addition of La inhibited the growth of coherent/semi-coherentθandβphases,which was very benefcial for the improvement of high-temperature strength.Under the optimal heat treatment process parameters of 500℃×4 h+190℃×4 h,the ultimate tensile strength(UTS)of the alloy reached 366.65 MPa.The high-temperature strength and elongation of the alloy reached 101.98 MPa and 13.77%at 350℃,respectively.展开更多
This study focused on meeting the stringent stability requirements of tubular segmented-in-series solid oxide fuel cells(SOFCs) in reducing and oxidizing atmospheres.To address this challenge,a bi-layer perovskite cer...This study focused on meeting the stringent stability requirements of tubular segmented-in-series solid oxide fuel cells(SOFCs) in reducing and oxidizing atmospheres.To address this challenge,a bi-layer perovskite ceramic interconnect was designed by controlling the oxygen partial pressure,because of the strong correlation between the conductivity of strontium-doped lanthanum titanate(LST) and the oxygen partial pressure.The LST powder was prepared using solid-phase and sol-gel methods,and their influence on particle size and sintering behavior was compared.LST/lanthanum strontium manganite(LSM) bi-layer ceramic interconnects with varying thicknesses were fabricated through screen printing and co-sintering.The results demonstrate favorable interfacial bonding and excellent chemical compatibility between the ceramic layers.The conductivity of the bi-layer interconnect exhibits a temperature-dependent behavior,peaking at 550℃.Simulation calculations and research findings validate that the co nductivity of the bi-layer interconnect is determined by the thickness of the LSM layer and the oxygen partial pressure at the interconnect interface.Optimal conductivity is achieved with a bilayer interconnect consisting of approximately 15 μm of LST and 4 μm of LSM.This can be attributed to the efficient regulation of oxygen partial pressure at the interface,effectively mitigating LSM decomposition caused by low oxygen partial pressure and the subsequent reduction in conductivity.These results provide valuable fundamental data and methodology for the development of high-performance interconnects for tubular segmented-in-series SOFCs.展开更多
基金financially supported by the National Natural Science Foundation of China[Grant No 52305341,U2341253,52371019]the Basic Scientific Research Project of Liaoning Provincial Education Department[JYTQN2023003].
文摘Grain size and texture can be controlled to improve the strength and ductility of magnesium rare-earth(Mg-RE)alloys by alloying.Directed energy deposition-arc(DED-arc)is a typical sub-rapid solidification process that contributes to the modification of the microstructure.In this paper,a series of novel Mg-3.0Nd-0.2Zn-0.3Zr-xCe(NZ30K-xCe)alloys with different Ce contents(0,0.1,0.3,0.5 wt.%)were prepared by DED-arc.The results show that the experimental alloys have lower porosity(≤0.11%).After adding 0.1 wt.%Ce,the average grain size decreases from 98.9±5.7μm to 49.8±1.0μm,and the texture is significantly weakened.Further additions of Ce(0.3 and 0.5 wt.%)do not lead to significant alterations in the average grain size and texture intensity when compared with the NZ30K-0.1Ce alloy.Grain refinement is related to the constitutional supercooling,and the texture weakening is connected to the solid solubility of Ce in the Mg matrix.The ultimate tensile strength and elongation of NZ30K-0.1Ce alloy are 37.2% and 61.3% higher than those of NZ30K alloy.Grain refinement and texture weakening are the reasons for the better strength-ductility of NZ30K-0.1Ce alloy.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.U2241232,U2341253 and 52375317)the National Key R&D Program of China(No.2022YFB3404204).
文摘In this study,the efects of diferent heat treatment process parameters on the microstructure and mechanical properties of Al-12Si-5Cu-1.1Mg-2.3Ni-0.3La alloy were explored.Research showed that eutectic Si underwent three stages during solution treatment:difusing,spheroidization and coarsening.As the solution temperature and time increased,the size of eutectic Si showed a trend of frst decreasing and then increasing.Compared with the heat treatment time,the heat treatment temperature had a more signifcant efect on the mechanical properties.The coarsening of microstructure was the main reason for the deterioration of mechanical properties.The Al_(3)Ti and Al_(3)CuNiLa in the microstructure after aging can signifcantly improve the mechanical properties of the alloy.The Al_(11)La_(3) with secondary precipitation occurred in the La-rich phase.The addition of La inhibited the growth of coherent/semi-coherentθandβphases,which was very benefcial for the improvement of high-temperature strength.Under the optimal heat treatment process parameters of 500℃×4 h+190℃×4 h,the ultimate tensile strength(UTS)of the alloy reached 366.65 MPa.The high-temperature strength and elongation of the alloy reached 101.98 MPa and 13.77%at 350℃,respectively.
基金Project supported by the National Key Research and Development Program of China (2021YFB4001400)。
文摘This study focused on meeting the stringent stability requirements of tubular segmented-in-series solid oxide fuel cells(SOFCs) in reducing and oxidizing atmospheres.To address this challenge,a bi-layer perovskite ceramic interconnect was designed by controlling the oxygen partial pressure,because of the strong correlation between the conductivity of strontium-doped lanthanum titanate(LST) and the oxygen partial pressure.The LST powder was prepared using solid-phase and sol-gel methods,and their influence on particle size and sintering behavior was compared.LST/lanthanum strontium manganite(LSM) bi-layer ceramic interconnects with varying thicknesses were fabricated through screen printing and co-sintering.The results demonstrate favorable interfacial bonding and excellent chemical compatibility between the ceramic layers.The conductivity of the bi-layer interconnect exhibits a temperature-dependent behavior,peaking at 550℃.Simulation calculations and research findings validate that the co nductivity of the bi-layer interconnect is determined by the thickness of the LSM layer and the oxygen partial pressure at the interconnect interface.Optimal conductivity is achieved with a bilayer interconnect consisting of approximately 15 μm of LST and 4 μm of LSM.This can be attributed to the efficient regulation of oxygen partial pressure at the interface,effectively mitigating LSM decomposition caused by low oxygen partial pressure and the subsequent reduction in conductivity.These results provide valuable fundamental data and methodology for the development of high-performance interconnects for tubular segmented-in-series SOFCs.
