The NiAl alloys modified by reactive element(RE),dysprosium(Dy),were produced by arc melting.The microstructures of the modified alloys were investigated by field emission-scanning electron microscope(FE-SEM)equipped ...The NiAl alloys modified by reactive element(RE),dysprosium(Dy),were produced by arc melting.The microstructures of the modified alloys were investigated by field emission-scanning electron microscope(FE-SEM)equipped with energy dispersive spectroscope(EDS)and back scatter detector.Cyclic oxidation tests at 1 200℃were conducted to assess the cyclic oxidation performance of the alloys.The Dy dopant prevents the surface rumpling of the oxide scale and the formation of cavities beneath the oxide scale.The pegs consisting of Dy-rich oxide inclusion core and an outer alumina sheath develop deeply in the alloy and improve the oxide scale adhesion.0.05%-0.1%(molar fraction)Dy dramatically improves the cyclic oxidation resistance of the NiAl alloy. Too high concentration of Dy is deleterious because of the fast oxidation rate caused by severe internal oxidation.展开更多
Dysprosium-doped Bi4Ti3O12 (Bi3.4Dy0.6Ti3O12, BDT) ferroelectric thin films were deposited on Pt(111)/Ti/SiO2/Si(111) substrates by chemical solution deposition (CSD) and crystallized in nitrogen, air and oxygen atmos...Dysprosium-doped Bi4Ti3O12 (Bi3.4Dy0.6Ti3O12, BDT) ferroelectric thin films were deposited on Pt(111)/Ti/SiO2/Si(111) substrates by chemical solution deposition (CSD) and crystallized in nitrogen, air and oxygen atmospheres, respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the crystal structure, the surface and cross-section morphology of the deposited ferroelectric films. The results show that the crystallization atmosphere has significant effect on determining the crystallization and ferroelectric properties of the BDT films. The film crystallized in nitrogen at a relatively low temperature of 650 ℃, exhibits excellent crystallinity and ferroelectricity with a remanent polarization of 2Pr = 24.9 μC/cm2 and a coercive field of 144.5 kV/cm. While the films annealed in air and oxygen at 650 ℃ do not show good crystallinity and ferroelectricity until they are annealed at 700 ℃. The structure evolution and ferroelectric properties of BDT thin films annealed under different temperatures (600?750 ℃) were also investigated. The crystallinity of the BDT films is improved and the average grain size increases when the annealing temperature increases from 600 ℃ to 750 ℃ at an interval of 50 ℃. However, the polarization of the films is not monotonous function of the annealing temperature.展开更多
基金Projects(50731001,50771009)supported by the National Natural Science Foundation of ChinaProject(PCSIRT/IRT 0512)supported bythe Program for Changjiang Scholars and Innovative Research Team in Chinese University
文摘The NiAl alloys modified by reactive element(RE),dysprosium(Dy),were produced by arc melting.The microstructures of the modified alloys were investigated by field emission-scanning electron microscope(FE-SEM)equipped with energy dispersive spectroscope(EDS)and back scatter detector.Cyclic oxidation tests at 1 200℃were conducted to assess the cyclic oxidation performance of the alloys.The Dy dopant prevents the surface rumpling of the oxide scale and the formation of cavities beneath the oxide scale.The pegs consisting of Dy-rich oxide inclusion core and an outer alumina sheath develop deeply in the alloy and improve the oxide scale adhesion.0.05%-0.1%(molar fraction)Dy dramatically improves the cyclic oxidation resistance of the NiAl alloy. Too high concentration of Dy is deleterious because of the fast oxidation rate caused by severe internal oxidation.
基金Project (05FJ2005) supported by the Key Project of Scientific and Technological Department of Hunan Province, China Project (05C095) supported by the Research Funds of Educational Department of Hunan Province, China
文摘Dysprosium-doped Bi4Ti3O12 (Bi3.4Dy0.6Ti3O12, BDT) ferroelectric thin films were deposited on Pt(111)/Ti/SiO2/Si(111) substrates by chemical solution deposition (CSD) and crystallized in nitrogen, air and oxygen atmospheres, respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the crystal structure, the surface and cross-section morphology of the deposited ferroelectric films. The results show that the crystallization atmosphere has significant effect on determining the crystallization and ferroelectric properties of the BDT films. The film crystallized in nitrogen at a relatively low temperature of 650 ℃, exhibits excellent crystallinity and ferroelectricity with a remanent polarization of 2Pr = 24.9 μC/cm2 and a coercive field of 144.5 kV/cm. While the films annealed in air and oxygen at 650 ℃ do not show good crystallinity and ferroelectricity until they are annealed at 700 ℃. The structure evolution and ferroelectric properties of BDT thin films annealed under different temperatures (600?750 ℃) were also investigated. The crystallinity of the BDT films is improved and the average grain size increases when the annealing temperature increases from 600 ℃ to 750 ℃ at an interval of 50 ℃. However, the polarization of the films is not monotonous function of the annealing temperature.
