The microstructures of liquid and amorphous Al 90 Fe 5Ce 5 alloys were studied by X ray diffraction (XRD), and the crystalline behavior of the amorphous alloy was also investigated by differential scanning calorimetry...The microstructures of liquid and amorphous Al 90 Fe 5Ce 5 alloys were studied by X ray diffraction (XRD), and the crystalline behavior of the amorphous alloy was also investigated by differential scanning calorimetry (DSC). The distinct pre peaks were found on the structure factors of the liquid and amorphous alloys. The quenching temperature affects the pre peak area, but does not affect its position. The reduction of quenching temperature decreases the crystallization temperature and the activation energy of the Al Fe Ce amorphous alloy. Quenched from 1 050 ℃, a novel structure with a fine dispersion of Al nanophase particles homogeneously distributed in the amorphous matrix was obtained. And the sensitivity of the Al Fe Ce amorphous alloy to the quenching temperature reflects the micro inhomogeneity of the melt.展开更多
Microstructure and impact toughness in the coarse grain heat-affected zone (CGHAZ) of HQ130 high strength steel were studied by using the weld thermo-simulation test. Fracture morphology and fine structure in the CGHA...Microstructure and impact toughness in the coarse grain heat-affected zone (CGHAZ) of HQ130 high strength steel were studied by using the weld thermo-simulation test. Fracture morphology and fine structure in the CGHAZ were analyzed by means of SEM, TEM and electron diffraction. Experimental results indicated that the impact toughness and hardness in the CGHAZ (T-m = 1350 degrees C) decreased with increasing cooling time (t(8/5)), and fracture morphology changed from dimple fracture into cleavage fracture. The reason for the toughness decrease is the formation of upper bainite. During application, the welding heat input should be strictly limited, to reduce brittleness in the CGHAZ of HQ130 steel.展开更多
Using a θ-θ X-ray diffractometer, the liquid structure of pure Fe was investigated and the diffraction intensity, structure factor, pair distribution function as well as the coordination number and atomic distance w...Using a θ-θ X-ray diffractometer, the liquid structure of pure Fe was investigated and the diffraction intensity, structure factor, pair distribution function as well as the coordination number and atomic distance were obtained. The experimental results showed that there was also a pre-peak on the curve of the structure factor of liquid pure Fe. The pre-peak is a mark of medium-range order in melts. According to the characteristics of pre-peak, an atomic model of liquid pure Fe is constructed, namely, the structure of liquid pure Fe is a combination of clusters consisting of bcc cells with shared vertexes and other atoms with random dense atom distribution.展开更多
THE phenomena of wetting on strengthening phases by liquid matrix metals is significant inmanufacturing metal matrix composites. Many methods have been proposed for improving thewettability of liquid metals on solids,...THE phenomena of wetting on strengthening phases by liquid matrix metals is significant inmanufacturing metal matrix composites. Many methods have been proposed for improving thewettability of liquid metals on solids, which include physical methods and chemical methods.Applying direct current (DC) is one of the physical methods. It has advantages in keeping展开更多
Thin alumina coatings were prepared on carbide tools to enhance their wear-resistant ability by dip coating from an aluminum alkoxide solution. The coating eventually obtained was perfectly integrated, without any mac...Thin alumina coatings were prepared on carbide tools to enhance their wear-resistant ability by dip coating from an aluminum alkoxide solution. The coating eventually obtained was perfectly integrated, without any macroscopic defect, and showed good performance in turning medium carbon steel, which presented a novel and promising coating method for cutting tools. The coating morphology before and after heat treatment was examined with the aid of a scanning electron microscope (SEM). The composition of coating and interface layer as well as the crystal structure of coating was characterized by X-ray diffraction (XRD). The elemental distribution near the interlayer was analyzed by electron probe microanalysis (EPMA).展开更多
Using a θ-θ X ray diffractometer the structure of liquid hypoeutectic Al Fe alloy at 675℃ and its change with different thermal histories are investigated . Liquid Al is used as a reference system. It is found that...Using a θ-θ X ray diffractometer the structure of liquid hypoeutectic Al Fe alloy at 675℃ and its change with different thermal histories are investigated . Liquid Al is used as a reference system. It is found that a pre peak appears on the small angle part of the structure factor of the nonsuperheated hypoeutectic Al Fe alloy, but disappears after superheating whereas the structure factors of liquid Al hardly change with the different thermal histories, and no pre peak can be observed on them. The appearance of a pre peak is a mark of the intermediate range order (IRO). The pre peak is taken as the correlation between Fe atoms on the IRO length scale. Assume that the crystalline structure is the first order approximation of the liquid structure. A model structure is constructed. The basic unit is a cube formed by 8 Al atoms on its corner and one Fe atom occupying its center. The translation of such a unit along its fourbody diagonals by the length of a diagonal can meet the requirement of the Fe_Fe distance and gives a DO 3 like structure. If the vacancy among the units is filled with fcc like Al cells, the composition of the entity is about Al 7Fe, close to that of the metastable phase Al 6Fe from rapid solidification. It is speculated that there are Al 6Fe like clusters in the liquid hypoeutectic Al Fe alloy.展开更多
The hybridized state of each atom changes with various changes of alloying elements and different alloying degrees. It is shown that during the course of alloying, the changes in the microsolid_state reflection such a...The hybridized state of each atom changes with various changes of alloying elements and different alloying degrees. It is shown that during the course of alloying, the changes in the microsolid_state reflection such as atomic hybridized state make the corresponding VES parameters change, and that affects the mechanical properties of Fe-3Al alloys.展开更多
It is found that the distribution of covalent electron pair number and covalent bond energy was nonuniform in carbides Fe 3C, (Fe,Cr) 3C and (Fe,Mn) 3C, in which the energy difference between the strongest and the wea...It is found that the distribution of covalent electron pair number and covalent bond energy was nonuniform in carbides Fe 3C, (Fe,Cr) 3C and (Fe,Mn) 3C, in which the energy difference between the strongest and the weakest bonds is very great. A criterion of covalent bond breaking during the heat treatment of M 3C pattern carbide is presented as follows. If the heat energy \%E\-\%w from heat treatment is higher than the diffusion activation energy \%Q\% of carbon atom in γ_Fe, the less the covalent bond energy \%E\% α is, the earlier the covalent bond α will be broken. According to the criterion, why the breaking of (Fe,Mn) 3C network was easier than that of Fe 3C network and why the breaking of (Fe, Cr) 3C network was more difficult than that of Fe 3C network are explained. It is indicated that Mn promoted the carbide to be spheroidized and Cr hindered the carbide from spheroidization during the heat treatment of carbides spheroidization.展开更多
A new method of measuring gear tooth dynamic deformation is proposed. Dynamic speckle photographs of the rotating gear tooth have been achieved by combining the pulsed ruby laser with the out-syn-signal. Double speckl...A new method of measuring gear tooth dynamic deformation is proposed. Dynamic speckle photographs of the rotating gear tooth have been achieved by combining the pulsed ruby laser with the out-syn-signal. Double speckle patterns of the whole mesh period of gear tooth are obtained by accurate time delay of the ruby laser. Gear tooth dynamic deformation of the whole mesh period is achieved using the automatic image processing. Testing results show that the trends of gear tooth deformation coincides with the calculation by the finite element method. The success of this new trying provides a new technique for the measurement of gear tooth dynamic deformation.展开更多
文摘The microstructures of liquid and amorphous Al 90 Fe 5Ce 5 alloys were studied by X ray diffraction (XRD), and the crystalline behavior of the amorphous alloy was also investigated by differential scanning calorimetry (DSC). The distinct pre peaks were found on the structure factors of the liquid and amorphous alloys. The quenching temperature affects the pre peak area, but does not affect its position. The reduction of quenching temperature decreases the crystallization temperature and the activation energy of the Al Fe Ce amorphous alloy. Quenched from 1 050 ℃, a novel structure with a fine dispersion of Al nanophase particles homogeneously distributed in the amorphous matrix was obtained. And the sensitivity of the Al Fe Ce amorphous alloy to the quenching temperature reflects the micro inhomogeneity of the melt.
文摘Microstructure and impact toughness in the coarse grain heat-affected zone (CGHAZ) of HQ130 high strength steel were studied by using the weld thermo-simulation test. Fracture morphology and fine structure in the CGHAZ were analyzed by means of SEM, TEM and electron diffraction. Experimental results indicated that the impact toughness and hardness in the CGHAZ (T-m = 1350 degrees C) decreased with increasing cooling time (t(8/5)), and fracture morphology changed from dimple fracture into cleavage fracture. The reason for the toughness decrease is the formation of upper bainite. During application, the welding heat input should be strictly limited, to reduce brittleness in the CGHAZ of HQ130 steel.
基金the National Natural science houndation of China (Grant No. 59871025).
文摘Using a θ-θ X-ray diffractometer, the liquid structure of pure Fe was investigated and the diffraction intensity, structure factor, pair distribution function as well as the coordination number and atomic distance were obtained. The experimental results showed that there was also a pre-peak on the curve of the structure factor of liquid pure Fe. The pre-peak is a mark of medium-range order in melts. According to the characteristics of pre-peak, an atomic model of liquid pure Fe is constructed, namely, the structure of liquid pure Fe is a combination of clusters consisting of bcc cells with shared vertexes and other atoms with random dense atom distribution.
文摘THE phenomena of wetting on strengthening phases by liquid matrix metals is significant inmanufacturing metal matrix composites. Many methods have been proposed for improving thewettability of liquid metals on solids, which include physical methods and chemical methods.Applying direct current (DC) is one of the physical methods. It has advantages in keeping
文摘Thin alumina coatings were prepared on carbide tools to enhance their wear-resistant ability by dip coating from an aluminum alkoxide solution. The coating eventually obtained was perfectly integrated, without any macroscopic defect, and showed good performance in turning medium carbon steel, which presented a novel and promising coating method for cutting tools. The coating morphology before and after heat treatment was examined with the aid of a scanning electron microscope (SEM). The composition of coating and interface layer as well as the crystal structure of coating was characterized by X-ray diffraction (XRD). The elemental distribution near the interlayer was analyzed by electron probe microanalysis (EPMA).
文摘Using a θ-θ X ray diffractometer the structure of liquid hypoeutectic Al Fe alloy at 675℃ and its change with different thermal histories are investigated . Liquid Al is used as a reference system. It is found that a pre peak appears on the small angle part of the structure factor of the nonsuperheated hypoeutectic Al Fe alloy, but disappears after superheating whereas the structure factors of liquid Al hardly change with the different thermal histories, and no pre peak can be observed on them. The appearance of a pre peak is a mark of the intermediate range order (IRO). The pre peak is taken as the correlation between Fe atoms on the IRO length scale. Assume that the crystalline structure is the first order approximation of the liquid structure. A model structure is constructed. The basic unit is a cube formed by 8 Al atoms on its corner and one Fe atom occupying its center. The translation of such a unit along its fourbody diagonals by the length of a diagonal can meet the requirement of the Fe_Fe distance and gives a DO 3 like structure. If the vacancy among the units is filled with fcc like Al cells, the composition of the entity is about Al 7Fe, close to that of the metastable phase Al 6Fe from rapid solidification. It is speculated that there are Al 6Fe like clusters in the liquid hypoeutectic Al Fe alloy.
文摘The hybridized state of each atom changes with various changes of alloying elements and different alloying degrees. It is shown that during the course of alloying, the changes in the microsolid_state reflection such as atomic hybridized state make the corresponding VES parameters change, and that affects the mechanical properties of Fe-3Al alloys.
文摘It is found that the distribution of covalent electron pair number and covalent bond energy was nonuniform in carbides Fe 3C, (Fe,Cr) 3C and (Fe,Mn) 3C, in which the energy difference between the strongest and the weakest bonds is very great. A criterion of covalent bond breaking during the heat treatment of M 3C pattern carbide is presented as follows. If the heat energy \%E\-\%w from heat treatment is higher than the diffusion activation energy \%Q\% of carbon atom in γ_Fe, the less the covalent bond energy \%E\% α is, the earlier the covalent bond α will be broken. According to the criterion, why the breaking of (Fe,Mn) 3C network was easier than that of Fe 3C network and why the breaking of (Fe, Cr) 3C network was more difficult than that of Fe 3C network are explained. It is indicated that Mn promoted the carbide to be spheroidized and Cr hindered the carbide from spheroidization during the heat treatment of carbides spheroidization.
文摘A new method of measuring gear tooth dynamic deformation is proposed. Dynamic speckle photographs of the rotating gear tooth have been achieved by combining the pulsed ruby laser with the out-syn-signal. Double speckle patterns of the whole mesh period of gear tooth are obtained by accurate time delay of the ruby laser. Gear tooth dynamic deformation of the whole mesh period is achieved using the automatic image processing. Testing results show that the trends of gear tooth deformation coincides with the calculation by the finite element method. The success of this new trying provides a new technique for the measurement of gear tooth dynamic deformation.
