Different structure models of a long-period ordered phase in Fe-C martenstie formed during aging have been checked by computer simulation of electron diffraction(ED) patterns based on these models.The results showed t...Different structure models of a long-period ordered phase in Fe-C martenstie formed during aging have been checked by computer simulation of electron diffraction(ED) patterns based on these models.The results showed that the simulated ED pattern of γ'-FexC(Ⅱ) model proposed by the present authors is in good agreement with experimentally observed ED pattern.It was also confirmed that the incommensurate superperiod stems from the coexistence of several γ'-Fe_xC(H) phases with different superperiods.The Fe(144)C(24)(Fe6C) model proposed by Uwakweh et al.generated ED patterns remarkably different from the experimental ones.展开更多
Transmission electron microscopy (TEM) is a very powerful technique for materials characteriza-tion, providing information relating to morphology, composition, and crystal structure. Selected area diffraction patterns...Transmission electron microscopy (TEM) is a very powerful technique for materials characteriza-tion, providing information relating to morphology, composition, and crystal structure. Selected area diffraction patterns (SADPs) are crystallographic data that can be obtained using a TEM in-strument. Conventional identification through SADP/TEM is tricky and tedious, thereby increasing the difficulty of phase identification. To establish a procedure for phase identification of known and unknown phases, in this study we examined two samples: one, a known phase, was Si with alignment;the other, unknown, was the TixOy phase at the 96.4Au-3Ni-0.6Ti interlayer/ yttria-stabilized zirconia (YSZ) interface of a steel/96.4Au-3Ni-0.6Ti interlayer/YSZ joint. The procedures for phase identification of the known and unknown phases are described herein using a series of SADPs and energy dispersive spectrometry within TEM that would be useful for general researchers.展开更多
It is well known that the lattice waves in alloy can be looked upon as the superposition of a series of plane waves with different wave vectors. Because of these plane wave′s diffraction action for X photon, there ar...It is well known that the lattice waves in alloy can be looked upon as the superposition of a series of plane waves with different wave vectors. Because of these plane wave′s diffraction action for X photon, there are two satellites (sidebands) around X ray main diffraction peak. With the wavelength and asymmetric factor α y of rectangle wave of the distribution of concentration introduced, the amplitude of modulation wave appearing along some crysallographic direction can be expressed clearly in the form of a sum of several diffraction wave vectors in the reciprocal space, and the diffracted intensity can be obtained. The X ray diffraction angle of sidebands strongly depends on the distribution of the wavelength. Fig.1b gives the simulated X ray diffraction profiles. It shows that when we fix the average modulated wavelength and change the distribution of wavelength, the angle difference between the satellite and main diffraction peak varies correspondingly. The simulated diffraction profiles are in good agreement with experimental results [1] (Fig.1a). The more diffuse the distribution of wavelength is, the nearer the sidebands are to main peak, and vice versa. In addition, the intensity and position of satellite are obviously restricted by the asymmetric factor of wave shape. Any lattice wave propagating in crystal can be resolved along coordinate axes. On the basis of the principle of superposition, all compositions of the lattice wave have diffraction profiles of themselves. Add two diffraction patterns perpendicular to each other on the reciprocal plane which is normal to the projected direction, we get the simulated TEM diffraction pattern of spinodal decomposition. Fig.2a is the TEM pattern by Kubo H [2] , Fig.2b and 2c are the simulated TEM patterns by Kubo H [2] and Khachaturyan A G [3] respectively. Our simulated TEM pattern (Fig.2d) is in good agreement with Fig.2a.展开更多
文摘Different structure models of a long-period ordered phase in Fe-C martenstie formed during aging have been checked by computer simulation of electron diffraction(ED) patterns based on these models.The results showed that the simulated ED pattern of γ'-FexC(Ⅱ) model proposed by the present authors is in good agreement with experimentally observed ED pattern.It was also confirmed that the incommensurate superperiod stems from the coexistence of several γ'-Fe_xC(H) phases with different superperiods.The Fe(144)C(24)(Fe6C) model proposed by Uwakweh et al.generated ED patterns remarkably different from the experimental ones.
文摘Transmission electron microscopy (TEM) is a very powerful technique for materials characteriza-tion, providing information relating to morphology, composition, and crystal structure. Selected area diffraction patterns (SADPs) are crystallographic data that can be obtained using a TEM in-strument. Conventional identification through SADP/TEM is tricky and tedious, thereby increasing the difficulty of phase identification. To establish a procedure for phase identification of known and unknown phases, in this study we examined two samples: one, a known phase, was Si with alignment;the other, unknown, was the TixOy phase at the 96.4Au-3Ni-0.6Ti interlayer/ yttria-stabilized zirconia (YSZ) interface of a steel/96.4Au-3Ni-0.6Ti interlayer/YSZ joint. The procedures for phase identification of the known and unknown phases are described herein using a series of SADPs and energy dispersive spectrometry within TEM that would be useful for general researchers.
文摘It is well known that the lattice waves in alloy can be looked upon as the superposition of a series of plane waves with different wave vectors. Because of these plane wave′s diffraction action for X photon, there are two satellites (sidebands) around X ray main diffraction peak. With the wavelength and asymmetric factor α y of rectangle wave of the distribution of concentration introduced, the amplitude of modulation wave appearing along some crysallographic direction can be expressed clearly in the form of a sum of several diffraction wave vectors in the reciprocal space, and the diffracted intensity can be obtained. The X ray diffraction angle of sidebands strongly depends on the distribution of the wavelength. Fig.1b gives the simulated X ray diffraction profiles. It shows that when we fix the average modulated wavelength and change the distribution of wavelength, the angle difference between the satellite and main diffraction peak varies correspondingly. The simulated diffraction profiles are in good agreement with experimental results [1] (Fig.1a). The more diffuse the distribution of wavelength is, the nearer the sidebands are to main peak, and vice versa. In addition, the intensity and position of satellite are obviously restricted by the asymmetric factor of wave shape. Any lattice wave propagating in crystal can be resolved along coordinate axes. On the basis of the principle of superposition, all compositions of the lattice wave have diffraction profiles of themselves. Add two diffraction patterns perpendicular to each other on the reciprocal plane which is normal to the projected direction, we get the simulated TEM diffraction pattern of spinodal decomposition. Fig.2a is the TEM pattern by Kubo H [2] , Fig.2b and 2c are the simulated TEM patterns by Kubo H [2] and Khachaturyan A G [3] respectively. Our simulated TEM pattern (Fig.2d) is in good agreement with Fig.2a.
