Rare earth (RE) atoms were permeated into the surface of Al bronze (Cu-7. gA1-1. 9 Sn) by the method of chemical heat treatment. The permeated layer was then analysed by TEM (Transmission Electron Microscope) , EPMA (...Rare earth (RE) atoms were permeated into the surface of Al bronze (Cu-7. gA1-1. 9 Sn) by the method of chemical heat treatment. The permeated layer was then analysed by TEM (Transmission Electron Microscope) , EPMA (Electronic Probe Microanalysis) and IMA (Ion Microprobe Appratus). The results show that CuREAl and dispersed η phase (Cu6Sn5) distribute in the layer, RE content decreases in the depth direction, and alloying elements (Al, Sn) are enriched in the outer layer and dilute in the second layer.展开更多
The cubic sodium tungsten bronzes, Na_xWO_3(x=0.854 and 0.814)were prepared by rare earths gaseous permeation method. Structural analysis was carried out by Rietveld method from powder X-ray diffraction data. The X-ra...The cubic sodium tungsten bronzes, Na_xWO_3(x=0.854 and 0.814)were prepared by rare earths gaseous permeation method. Structural analysis was carried out by Rietveld method from powder X-ray diffraction data. The X-ray diffraction profile calculated with cubic P32 models are in good agreement with the observed X-ray diffraction patterns. There is only a little difference in W-O bond and Na-O bond between Na_(0.854)WO_3 and Na_(0.814)WO_3. Conductivity measurements indicate that Na_xWO_3 show anomalous semiconducting behavior and percolation model was used to interpret it.展开更多
New polyoxometalate α-K 12H 3[Y(BW 11O 39) 2]·25H 2O was synthesized and treated by high temperature gaseous rare earth permeation to prepare tungsten bronze K 0.475WO 3. XRD, TG-DTA, XPS, ...New polyoxometalate α-K 12H 3[Y(BW 11O 39) 2]·25H 2O was synthesized and treated by high temperature gaseous rare earth permeation to prepare tungsten bronze K 0.475WO 3. XRD, TG-DTA, XPS, 183W-NMR,CV and AC impedance spectra were used to characterize the resulting material. The results of XPS indicate that La has permeated and diffused into the body of the sample and exists in the forms of binding with other components. The crystal structure parameters of K 0.475WO 3 were obtained by the analysis of XRD, which shows tetragonal crystal system with lattice parameters: a=12 28 nm, c=3.833 nm, V=578.48 nm -3. The conductivities calculated from the results of AC impedance spectra of the material increase with the increasing of temperature, which shows a semiconductor character.展开更多
It is indicated that the initial layer of RE-B-Al permeation is mainly composed of Fe2B by means of TEM and EDAX, and (RE0.65 Feo0.35) 23B6 is found after RE permeation for 4 h. (Fe0.8, RE0.2)6B is found in the layer...It is indicated that the initial layer of RE-B-Al permeation is mainly composed of Fe2B by means of TEM and EDAX, and (RE0.65 Feo0.35) 23B6 is found after RE permeation for 4 h. (Fe0.8, RE0.2)6B is found in the layer of RE-B-Al permeation and the distance of crystal face of α-Fe is enlarged. The mechanism of formation of boride was analyzed. Prevention of compounds, such as Al, C etc., on dislocation movement, strengthening of grain boundary, dislocation and solution are responsible for the properties in the permeation layer.展开更多
Potassium tungsten bronze KxLayWO3 (x>0.5 and y<0.01) was synthesized by rare earth co-permeation method using α-K7[SiMg3(OH2)3W9O37] as the precursor. Binding energies of La, W, O and C were determined by XPS....Potassium tungsten bronze KxLayWO3 (x>0.5 and y<0.01) was synthesized by rare earth co-permeation method using α-K7[SiMg3(OH2)3W9O37] as the precursor. Binding energies of La, W, O and C were determined by XPS. From the XPS data, a peak at 34.21 eV indicates that some W6+ turned into W5+ by rare earth co- permeation. The binding energies La3d were the same in the surface and inner of the composite, showing that rare earth element La could diffuse into the body of the composite and the compound of KxLayWO3 was formed at the same time. The binding energies of O1s in KxLayWO3 surface were 531.4 eV and 532.0 eV, respectively, while peak at 531.4 eV disappeared through etching process. The result implies that the binding energy of 531.4 eV was due to the adsorbent O. In addition, the binding energies of C1s in the surface were 283.5 eV, 285.0 eV and 286.7 eV respectively, while the inner had only one peak at 285.0 eV due to standard C1s. This proves that there was no C in the core.展开更多
Different from the grain boundary diffusion process(GBDP),which is suitable for modifying thin magnet,a green-pressing agents permeation process(GAPP)that uses low melting point alloys was applied to the Nd-Fe-B green...Different from the grain boundary diffusion process(GBDP),which is suitable for modifying thin magnet,a green-pressing agents permeation process(GAPP)that uses low melting point alloys was applied to the Nd-Fe-B green compact with a thickness over 15 mm to reconstruct the boundary microstructure of a sintered Nd-Fe-B magnet.The coercivity increases from 12.3 kOe for the sample free of Pr80Al20 to16.8 kOe for the sample with 2 wt%Pr80Al20.By further increasing the Pr80Al20 content to 3 wt%,the coercivity increases slightly,but the remanence and Hk/Hcj deteriorate obviously.The optimal comprehensive properties of Hcj=16.8 kOe,Br=13.4 kG and Hk/Hcj=0.975 are obtained at 2 wt%Pr80Al20,since matrix phase grains are separated by relatively continuous thin grain boundary layers,which weaken the magnetic coupling between adjacent grains.The coercivities of the samples from the GAPP that use2 wt%Pr80Al20,Pr70Al30 and Pr60Tb20Al20 alloys,respectively,can be enhanced to a large extent.However,the coercivity of the magnet reconstructed with Pr80Al20 is lower than that of the sample with Pr60Tb20Al20 but is higher than that of the sample reconstructed with Pr70Cu30 alloy.Moreover,the coercivity of the sample from the GAPP using 2 wt%Pr80Al20 is much higher than that of the sample from the GBDP,which is due to a nearly uniform boundary microstructure from the surface to the interior of the thick magnet from the GAPP,thus providing new insights into the fabrication of thick and bulky permanent magnets with high coercivity.展开更多
A tritium permeation barrier is required in fusion blankets for the reduction of fuel loss and radiological hazard.In this study,an Al2O3/Y2O3 composite coating was prepared on 316 L stainless steel by radiofrequency ...A tritium permeation barrier is required in fusion blankets for the reduction of fuel loss and radiological hazard.In this study,an Al2O3/Y2O3 composite coating was prepared on 316 L stainless steel by radiofrequency magnetron sputtering in order to improve the tritium permeation resistance.The microstructure and the phase composition of the Al2O3/Y2O3 composite coating are observed by scanning electron microscopy,transmission electron microscopy and grazing incidence X-ray diffraction.Moreover,Auger electron spectroscopy was used to characterize the depth profiles of Al,Y and O elements.The results clearly indicate that the Al2O3/Y2O3 composite coating is fully dense and the total thickness is approximately 340 nm.The Al2O3/Y2O3 coating consists of an amorphous Al2O3 and the cubic Y2O3,in which Al,Y and O elements are homogeneously distributed in the vertical base direction.Furthermore,the deuterium permeation property of the Al2O3/Y2O3 composite coating was measured by the gas phase permeation method.The results show that the introduction of an interface and the existence of a tiny amount of micro-defects improve the deuterium resistance of the Al2O3/Y2O3 coating,and its deuterium permeation reduction factor is 536-750 at 873-973 K.Therefore,it is concluded that the Al2O3/Y2O3 co mposite coating as deuterium permeation barrier can significa ntly enha nce the deuterium permeation resistance property.展开更多
文摘Rare earth (RE) atoms were permeated into the surface of Al bronze (Cu-7. gA1-1. 9 Sn) by the method of chemical heat treatment. The permeated layer was then analysed by TEM (Transmission Electron Microscope) , EPMA (Electronic Probe Microanalysis) and IMA (Ion Microprobe Appratus). The results show that CuREAl and dispersed η phase (Cu6Sn5) distribute in the layer, RE content decreases in the depth direction, and alloying elements (Al, Sn) are enriched in the outer layer and dilute in the second layer.
文摘The cubic sodium tungsten bronzes, Na_xWO_3(x=0.854 and 0.814)were prepared by rare earths gaseous permeation method. Structural analysis was carried out by Rietveld method from powder X-ray diffraction data. The X-ray diffraction profile calculated with cubic P32 models are in good agreement with the observed X-ray diffraction patterns. There is only a little difference in W-O bond and Na-O bond between Na_(0.854)WO_3 and Na_(0.814)WO_3. Conductivity measurements indicate that Na_xWO_3 show anomalous semiconducting behavior and percolation model was used to interpret it.
文摘New polyoxometalate α-K 12H 3[Y(BW 11O 39) 2]·25H 2O was synthesized and treated by high temperature gaseous rare earth permeation to prepare tungsten bronze K 0.475WO 3. XRD, TG-DTA, XPS, 183W-NMR,CV and AC impedance spectra were used to characterize the resulting material. The results of XPS indicate that La has permeated and diffused into the body of the sample and exists in the forms of binding with other components. The crystal structure parameters of K 0.475WO 3 were obtained by the analysis of XRD, which shows tetragonal crystal system with lattice parameters: a=12 28 nm, c=3.833 nm, V=578.48 nm -3. The conductivities calculated from the results of AC impedance spectra of the material increase with the increasing of temperature, which shows a semiconductor character.
文摘It is indicated that the initial layer of RE-B-Al permeation is mainly composed of Fe2B by means of TEM and EDAX, and (RE0.65 Feo0.35) 23B6 is found after RE permeation for 4 h. (Fe0.8, RE0.2)6B is found in the layer of RE-B-Al permeation and the distance of crystal face of α-Fe is enlarged. The mechanism of formation of boride was analyzed. Prevention of compounds, such as Al, C etc., on dislocation movement, strengthening of grain boundary, dislocation and solution are responsible for the properties in the permeation layer.
文摘Potassium tungsten bronze KxLayWO3 (x>0.5 and y<0.01) was synthesized by rare earth co-permeation method using α-K7[SiMg3(OH2)3W9O37] as the precursor. Binding energies of La, W, O and C were determined by XPS. From the XPS data, a peak at 34.21 eV indicates that some W6+ turned into W5+ by rare earth co- permeation. The binding energies La3d were the same in the surface and inner of the composite, showing that rare earth element La could diffuse into the body of the composite and the compound of KxLayWO3 was formed at the same time. The binding energies of O1s in KxLayWO3 surface were 531.4 eV and 532.0 eV, respectively, while peak at 531.4 eV disappeared through etching process. The result implies that the binding energy of 531.4 eV was due to the adsorbent O. In addition, the binding energies of C1s in the surface were 283.5 eV, 285.0 eV and 286.7 eV respectively, while the inner had only one peak at 285.0 eV due to standard C1s. This proves that there was no C in the core.
基金Project supported by the National Natural Science Foundation of China(51401021)the State Key Laboratory Advanced Metals and Materials(20162-14).
文摘Different from the grain boundary diffusion process(GBDP),which is suitable for modifying thin magnet,a green-pressing agents permeation process(GAPP)that uses low melting point alloys was applied to the Nd-Fe-B green compact with a thickness over 15 mm to reconstruct the boundary microstructure of a sintered Nd-Fe-B magnet.The coercivity increases from 12.3 kOe for the sample free of Pr80Al20 to16.8 kOe for the sample with 2 wt%Pr80Al20.By further increasing the Pr80Al20 content to 3 wt%,the coercivity increases slightly,but the remanence and Hk/Hcj deteriorate obviously.The optimal comprehensive properties of Hcj=16.8 kOe,Br=13.4 kG and Hk/Hcj=0.975 are obtained at 2 wt%Pr80Al20,since matrix phase grains are separated by relatively continuous thin grain boundary layers,which weaken the magnetic coupling between adjacent grains.The coercivities of the samples from the GAPP that use2 wt%Pr80Al20,Pr70Al30 and Pr60Tb20Al20 alloys,respectively,can be enhanced to a large extent.However,the coercivity of the magnet reconstructed with Pr80Al20 is lower than that of the sample with Pr60Tb20Al20 but is higher than that of the sample reconstructed with Pr70Cu30 alloy.Moreover,the coercivity of the sample from the GAPP using 2 wt%Pr80Al20 is much higher than that of the sample from the GBDP,which is due to a nearly uniform boundary microstructure from the surface to the interior of the thick magnet from the GAPP,thus providing new insights into the fabrication of thick and bulky permanent magnets with high coercivity.
基金Project supported by the National Natural Science Foundation of China(51671034)。
文摘A tritium permeation barrier is required in fusion blankets for the reduction of fuel loss and radiological hazard.In this study,an Al2O3/Y2O3 composite coating was prepared on 316 L stainless steel by radiofrequency magnetron sputtering in order to improve the tritium permeation resistance.The microstructure and the phase composition of the Al2O3/Y2O3 composite coating are observed by scanning electron microscopy,transmission electron microscopy and grazing incidence X-ray diffraction.Moreover,Auger electron spectroscopy was used to characterize the depth profiles of Al,Y and O elements.The results clearly indicate that the Al2O3/Y2O3 composite coating is fully dense and the total thickness is approximately 340 nm.The Al2O3/Y2O3 coating consists of an amorphous Al2O3 and the cubic Y2O3,in which Al,Y and O elements are homogeneously distributed in the vertical base direction.Furthermore,the deuterium permeation property of the Al2O3/Y2O3 composite coating was measured by the gas phase permeation method.The results show that the introduction of an interface and the existence of a tiny amount of micro-defects improve the deuterium resistance of the Al2O3/Y2O3 coating,and its deuterium permeation reduction factor is 536-750 at 873-973 K.Therefore,it is concluded that the Al2O3/Y2O3 co mposite coating as deuterium permeation barrier can significa ntly enha nce the deuterium permeation resistance property.
