Edge-to-edge matching(E2EM)model was used to predict the potency of LaB_(6) as the heterogeneous nucleation substrate for primary Al_(13)Mn_(4)Si_(8) phase formed during the solidification of Al−Si−Cu−Mn heat-resistan...Edge-to-edge matching(E2EM)model was used to predict the potency of LaB_(6) as the heterogeneous nucleation substrate for primary Al_(13)Mn_(4)Si_(8) phase formed during the solidification of Al−Si−Cu−Mn heat-resistant alloy.There are five pairs of orientation relationships(ORs)between LaB_(6) and Al_(13)Mn_(4)Si_(8) phases which meet the criteria of E2EM model.One pair of plane ORs((110)LaB_(6)//(110)Al_(13)Mn_(4)Si_(8))are demonstrated by TEM observation.This strongly indicates that the LaB_(6) phase can act as the heterogeneous nucleation substrate for the primary Al_(13)Mn_(4)Si_(8) phase.1.0 wt.%of Al−2La−1B master alloy was also added into Al−12Si−4Cu−2Mn alloy to evaluate the refining effect by microstructure observation and tensile test.Experimental results show that addition of Al−2La−1B master alloy can significantly refine the primary Al_(13)Mn_(4)Si_(8) phase,supporting the prediction accuracy of E2EM model.However,such refinement of primary Al_(13)Mn_(4)Si_(8) phase does not lead to an improvement in strength.This is due to the larger difference in elastic modulus between the finally formed Al_(13)Mn_(4)Si_(8) phase and aluminum matrix than that of Al_(15)Mn_(3)Si_(2) phase.展开更多
Binary nanocrystalline rare-earth hexaboride is regarded as one of the promising optical absorption materials that possess the high transparency for visible light and the strong absorption for NIR due to the effects o...Binary nanocrystalline rare-earth hexaboride is regarded as one of the promising optical absorption materials that possess the high transparency for visible light and the strong absorption for NIR due to the effects of localized surface plasmon resonance.In present work,we experimentally investigated the structural and optical absorption of ternary nanocrystalline Eu-doped SmB6 powder.As a result,it is found that the reaction temperature as an important factor not only refines the grain size,but also improves the powder dispersion of synthesized samples.The optical absorption results reveal that the transmittance wavelength of nanocrystalline SmB6 increases from 696 nm to exceeding 1000 nm with the Eu doping content increasing to x=0.8.Theo retically,in order to study the transmittance wavele ngth tunable mechanisms of nanocrystalline Eu-doped SmB6,the electronic structure,density of states and energy loss function were calculated by first-principle calculation.It shows that the En2+doping into SmB6 effectively reduces the plasma frequency excitation energy from 1.48 to 1.25 eV and leads to the transmittance wavelength redshift toward a higher wavelength.Based on above meaningful studies,present work is helpful for extension of optical applications of nanocrystalline SmB6 powder.展开更多
LaB6 powders were synthesized in large scale by salt-assisted combustion synthesis(CS) with different NaCl diluent contents. The variety of phases, particle size and purity of the powders were investigated using X-ray...LaB6 powders were synthesized in large scale by salt-assisted combustion synthesis(CS) with different NaCl diluent contents. The variety of phases, particle size and purity of the powders were investigated using X-ray diffraction(XRD), scanning electron microscopy(SEM), energy dispersive spectrometer(EDS), and transmission electron microscope(TEM). With increase of NaCl content, the adiabatic combustion temperature of the reaction system linearly declines, the average particle size of leached products decreases, the impurity phases are easier to remove, and the products purity enhances obviously. When NaCl content is 40 wt%, the purity of the superfine powders of LaBis more than 98 wt%, and the average particle size is 380 nm.展开更多
基金supported by Jiangsu Key Laboratory Metallic Materials, China (No. BM2007204)the Fundamental Research Funds for the Central Universities, China (No. 2242016k40011)。
文摘Edge-to-edge matching(E2EM)model was used to predict the potency of LaB_(6) as the heterogeneous nucleation substrate for primary Al_(13)Mn_(4)Si_(8) phase formed during the solidification of Al−Si−Cu−Mn heat-resistant alloy.There are five pairs of orientation relationships(ORs)between LaB_(6) and Al_(13)Mn_(4)Si_(8) phases which meet the criteria of E2EM model.One pair of plane ORs((110)LaB_(6)//(110)Al_(13)Mn_(4)Si_(8))are demonstrated by TEM observation.This strongly indicates that the LaB_(6) phase can act as the heterogeneous nucleation substrate for the primary Al_(13)Mn_(4)Si_(8) phase.1.0 wt.%of Al−2La−1B master alloy was also added into Al−12Si−4Cu−2Mn alloy to evaluate the refining effect by microstructure observation and tensile test.Experimental results show that addition of Al−2La−1B master alloy can significantly refine the primary Al_(13)Mn_(4)Si_(8) phase,supporting the prediction accuracy of E2EM model.However,such refinement of primary Al_(13)Mn_(4)Si_(8) phase does not lead to an improvement in strength.This is due to the larger difference in elastic modulus between the finally formed Al_(13)Mn_(4)Si_(8) phase and aluminum matrix than that of Al_(15)Mn_(3)Si_(2) phase.
基金Project supported by the National Natural Science Foundation of China(51662034)。
文摘Binary nanocrystalline rare-earth hexaboride is regarded as one of the promising optical absorption materials that possess the high transparency for visible light and the strong absorption for NIR due to the effects of localized surface plasmon resonance.In present work,we experimentally investigated the structural and optical absorption of ternary nanocrystalline Eu-doped SmB6 powder.As a result,it is found that the reaction temperature as an important factor not only refines the grain size,but also improves the powder dispersion of synthesized samples.The optical absorption results reveal that the transmittance wavelength of nanocrystalline SmB6 increases from 696 nm to exceeding 1000 nm with the Eu doping content increasing to x=0.8.Theo retically,in order to study the transmittance wavele ngth tunable mechanisms of nanocrystalline Eu-doped SmB6,the electronic structure,density of states and energy loss function were calculated by first-principle calculation.It shows that the En2+doping into SmB6 effectively reduces the plasma frequency excitation energy from 1.48 to 1.25 eV and leads to the transmittance wavelength redshift toward a higher wavelength.Based on above meaningful studies,present work is helpful for extension of optical applications of nanocrystalline SmB6 powder.
基金supported by the National Natural Science Foundation of China(51561020)
文摘LaB6 powders were synthesized in large scale by salt-assisted combustion synthesis(CS) with different NaCl diluent contents. The variety of phases, particle size and purity of the powders were investigated using X-ray diffraction(XRD), scanning electron microscopy(SEM), energy dispersive spectrometer(EDS), and transmission electron microscope(TEM). With increase of NaCl content, the adiabatic combustion temperature of the reaction system linearly declines, the average particle size of leached products decreases, the impurity phases are easier to remove, and the products purity enhances obviously. When NaCl content is 40 wt%, the purity of the superfine powders of LaBis more than 98 wt%, and the average particle size is 380 nm.
