The present study was aimed at determining the surface strain/stress state in an Ni-based single-... more The present study was aimed at determining the surface strain/stress state in an Ni-based single-crystal (SC) superalloy that was subjected to two different cooling rates from solid solution temperature through using the X-ray diffraction (XRD) method. The normal stresses σ 11 s and σ 22 s were determined, then the Von Mises stresses ( σ V M s ) were derived from them. Field emission gun scanning electron microscope (FEG-SEM) and transmission electron microscope (TEM) micrographs were taken to illustrate the strain/stress state change. The precipitation of the secondary γ′ phases in the γ phase and the formation of the dislocation in the interphase upon a slower cooling rate caused the γ phase lattice distortion to increase, so a larger σ V M s of the γ phase was realized in comparison to the faster cooling sample. For both of the two cooling modes, we found that the σ V M s of the γ′ phase increased due to the growth of the γ′ phase during the aging process. Also, the aging process...
The structural, electronic and magnetic properties of a 9-layer symmetrical FeMoO terminated (001... more The structural, electronic and magnetic properties of a 9-layer symmetrical FeMoO terminated (001)-oriented slab of double perovskite Sr2FeMoO6 have been studied by using the first-principle projector augmented wave potential within the generalized gradient approximation taking into account the on-site Coulomb repulsive (U = 2.0 eV for Fe and 1.0 eV for Mo). An outward relaxation is observed for each layer of the first four layers and the accompanying layer's rumpling has a decreasing trend from layer 1 to layer 4. Along Fe–O–Mo–O–Fe or Mo–O–Fe–O–Mo chain, the oxygen atom is closer to the adjacent Mo atom than to the adjacent Fe atom. The half-metallic nature ensures the symmetrical FeMoO terminated (001)-oriented slab of double perovskite Sr2FeMoO6 to be a potential application in spintronic devices. The Jahn–Teller structural distortions and the outward relaxations lead to the differences between pz state and similar px and py states, between dxy state and similar dyz and dxz ...
A family of layered lanthanide (Pr, Nd, Sm, Eu, and Gd) hydroxide nanowires (NWs) has been synthe... more A family of layered lanthanide (Pr, Nd, Sm, Eu, and Gd) hydroxide nanowires (NWs) has been synthesized via a hydrothermal route. These NWs are ∼8 nm in diameter and a few micrometres in length. The obtained Eu- and Gd-based layered hydroxide NWs consist of layered structure with two interlayer spacings. The effects of hydrothermal temperature and time on the transition of the layered structure were investigated. Photoluminescence of the Eu-based layered hydroxide NWs was also studied. These layered lanthanide hydroxide NWs combine the advantages of lanthanide and layered hydroxides, which will expand the inorganic layered materials and can be expected to be used as building blocks for further fabrication of functional nanostructures.
... J. Nanosci. Nanotechnol. 10, 840846, 2010 845 Page 7. Delivered by Ingenta to: ? IP : 93.91.... more ... J. Nanosci. Nanotechnol. 10, 840846, 2010 845 Page 7. Delivered by Ingenta to: ? IP : 93.91.26.12 Thu, 24 Mar 2011 04:19:15 RESEARCH AR TICLE ... Nanotechnol. 1, 49 (2001). 33. D. Golberg, FF Xu, and Y. Bando, Appl. Phys. A 76, 479 (2003). 34. ...
Superplasticity and crystallographic orientation distribution of an Al-Mg-Mn sheet subjected to f... more Superplasticity and crystallographic orientation distribution of an Al-Mg-Mn sheet subjected to friction stir processing (FSP) have been investigated. The FSP was developed by adapting the concepts of friction stir welding to obtain a fine grain size in a stirred zone. Grain refinement was achieved by the FSP to give a smaller grain size of about 4µm than a value of 26µm in the as-received sheet. The SEM/EBSP analysis of the specimen before and after the FSP revealed a fraction of high angle grain boundaries became a higher percentage of 83% due to the FSP than 75% before. The elongation to failure in the FSPed sample had a maximum value of 361% at 773K and 1.1×10-3 s-1. Further, change in crystallographic orientation distribution is investigated during tensile testing in consideration of deformation mechanism.
The mechanical properties of systems consisting of copper coatings electrodeposited on both brass... more The mechanical properties of systems consisting of copper coatings electrodeposited on both brass sheet (BS) and thick electrodeposited nickel coating (ED Ni) substrates have been investigated. The electrodeposition of copper coatings was performed with and without the ultrasound assistance. The ultrasound application decreases root mean square (RMS) roughness of deposited Cu coating on both applied substrates, as obtained from non-contact AFM measurement. The coating roughness is highly dependent on the substrate roughness, being the smallest for the Cu coatings deposited on ED Ni substrate with the ultrasound mixing. The hardness and adhesion properties were characterized using the Vickers microindentation test. Model of Korsunsky was applied to the experimental data for determination the film hardness and the model of Chen-Gao was used for the adhesion evaluation. The introduction of ultrasonic agitation caused the changes in the film microstructure, and consequently in the mecha...
The structural stability and theoretical strength of a Au face-centered cubic (FCC) crystal under... more The structural stability and theoretical strength of a Au face-centered cubic (FCC) crystal under uniaxial loading is investigated by combining the modified analytical embedded atom method (MAEAM) with Born stability criteria. The results show that under sufficient compression, there exists a stress-free body-centered cubic (BCC) phase, which is unstable and slips spontaneously to a stress-free metastable body-centered tetragonal phase by consuming internal energy. The structural energy difference between the BCC and FCC phases is in good agreement with the experimental value. The stable region ranged from –2.21 GPa to 6.31 GPa in the theoretical strength or from –9.83% to 7.87% in the strain correspondingly.PACS Nos.: 62.20.–x, 61.50.Ks, 81.05.Bx
ABSTRACT The recrystallisation behaviour of S30432 shot peened deformation surface layer during i... more ABSTRACT The recrystallisation behaviour of S30432 shot peened deformation surface layer during isothermal annealing has been investigated by X-ray diffraction line profile analysis method. The results revealed that annealing time and temperature were two key parameters for isothermal annealing process of S30432 steel. With higher annealing temperature, the recrystallisation behaviour in the shot peened deformed layer was more obvious. Based on the results of line profile analysis, the recrystallisation activation energy and microstrain relaxation energy were calculated. In addition, after isothermal annealing, the depth distribution of domain size in the deformed layer was also investigated and discussed in details. According to the analysis, the results showed that the thermostability of S30432 shot peened surface layer was relatively stable when the annealing temperature was below 650 degrees C.
The present study was aimed at determining the surface strain/stress state in an Ni-based single-... more The present study was aimed at determining the surface strain/stress state in an Ni-based single-crystal (SC) superalloy that was subjected to two different cooling rates from solid solution temperature through using the X-ray diffraction (XRD) method. The normal stresses σ 11 s and σ 22 s were determined, then the Von Mises stresses ( σ V M s ) were derived from them. Field emission gun scanning electron microscope (FEG-SEM) and transmission electron microscope (TEM) micrographs were taken to illustrate the strain/stress state change. The precipitation of the secondary γ′ phases in the γ phase and the formation of the dislocation in the interphase upon a slower cooling rate caused the γ phase lattice distortion to increase, so a larger σ V M s of the γ phase was realized in comparison to the faster cooling sample. For both of the two cooling modes, we found that the σ V M s of the γ′ phase increased due to the growth of the γ′ phase during the aging process. Also, the aging process...
The structural, electronic and magnetic properties of a 9-layer symmetrical FeMoO terminated (001... more The structural, electronic and magnetic properties of a 9-layer symmetrical FeMoO terminated (001)-oriented slab of double perovskite Sr2FeMoO6 have been studied by using the first-principle projector augmented wave potential within the generalized gradient approximation taking into account the on-site Coulomb repulsive (U = 2.0 eV for Fe and 1.0 eV for Mo). An outward relaxation is observed for each layer of the first four layers and the accompanying layer's rumpling has a decreasing trend from layer 1 to layer 4. Along Fe–O–Mo–O–Fe or Mo–O–Fe–O–Mo chain, the oxygen atom is closer to the adjacent Mo atom than to the adjacent Fe atom. The half-metallic nature ensures the symmetrical FeMoO terminated (001)-oriented slab of double perovskite Sr2FeMoO6 to be a potential application in spintronic devices. The Jahn–Teller structural distortions and the outward relaxations lead to the differences between pz state and similar px and py states, between dxy state and similar dyz and dxz ...
A family of layered lanthanide (Pr, Nd, Sm, Eu, and Gd) hydroxide nanowires (NWs) has been synthe... more A family of layered lanthanide (Pr, Nd, Sm, Eu, and Gd) hydroxide nanowires (NWs) has been synthesized via a hydrothermal route. These NWs are ∼8 nm in diameter and a few micrometres in length. The obtained Eu- and Gd-based layered hydroxide NWs consist of layered structure with two interlayer spacings. The effects of hydrothermal temperature and time on the transition of the layered structure were investigated. Photoluminescence of the Eu-based layered hydroxide NWs was also studied. These layered lanthanide hydroxide NWs combine the advantages of lanthanide and layered hydroxides, which will expand the inorganic layered materials and can be expected to be used as building blocks for further fabrication of functional nanostructures.
... J. Nanosci. Nanotechnol. 10, 840846, 2010 845 Page 7. Delivered by Ingenta to: ? IP : 93.91.... more ... J. Nanosci. Nanotechnol. 10, 840846, 2010 845 Page 7. Delivered by Ingenta to: ? IP : 93.91.26.12 Thu, 24 Mar 2011 04:19:15 RESEARCH AR TICLE ... Nanotechnol. 1, 49 (2001). 33. D. Golberg, FF Xu, and Y. Bando, Appl. Phys. A 76, 479 (2003). 34. ...
Superplasticity and crystallographic orientation distribution of an Al-Mg-Mn sheet subjected to f... more Superplasticity and crystallographic orientation distribution of an Al-Mg-Mn sheet subjected to friction stir processing (FSP) have been investigated. The FSP was developed by adapting the concepts of friction stir welding to obtain a fine grain size in a stirred zone. Grain refinement was achieved by the FSP to give a smaller grain size of about 4µm than a value of 26µm in the as-received sheet. The SEM/EBSP analysis of the specimen before and after the FSP revealed a fraction of high angle grain boundaries became a higher percentage of 83% due to the FSP than 75% before. The elongation to failure in the FSPed sample had a maximum value of 361% at 773K and 1.1×10-3 s-1. Further, change in crystallographic orientation distribution is investigated during tensile testing in consideration of deformation mechanism.
The mechanical properties of systems consisting of copper coatings electrodeposited on both brass... more The mechanical properties of systems consisting of copper coatings electrodeposited on both brass sheet (BS) and thick electrodeposited nickel coating (ED Ni) substrates have been investigated. The electrodeposition of copper coatings was performed with and without the ultrasound assistance. The ultrasound application decreases root mean square (RMS) roughness of deposited Cu coating on both applied substrates, as obtained from non-contact AFM measurement. The coating roughness is highly dependent on the substrate roughness, being the smallest for the Cu coatings deposited on ED Ni substrate with the ultrasound mixing. The hardness and adhesion properties were characterized using the Vickers microindentation test. Model of Korsunsky was applied to the experimental data for determination the film hardness and the model of Chen-Gao was used for the adhesion evaluation. The introduction of ultrasonic agitation caused the changes in the film microstructure, and consequently in the mecha...
The structural stability and theoretical strength of a Au face-centered cubic (FCC) crystal under... more The structural stability and theoretical strength of a Au face-centered cubic (FCC) crystal under uniaxial loading is investigated by combining the modified analytical embedded atom method (MAEAM) with Born stability criteria. The results show that under sufficient compression, there exists a stress-free body-centered cubic (BCC) phase, which is unstable and slips spontaneously to a stress-free metastable body-centered tetragonal phase by consuming internal energy. The structural energy difference between the BCC and FCC phases is in good agreement with the experimental value. The stable region ranged from –2.21 GPa to 6.31 GPa in the theoretical strength or from –9.83% to 7.87% in the strain correspondingly.PACS Nos.: 62.20.–x, 61.50.Ks, 81.05.Bx
ABSTRACT The recrystallisation behaviour of S30432 shot peened deformation surface layer during i... more ABSTRACT The recrystallisation behaviour of S30432 shot peened deformation surface layer during isothermal annealing has been investigated by X-ray diffraction line profile analysis method. The results revealed that annealing time and temperature were two key parameters for isothermal annealing process of S30432 steel. With higher annealing temperature, the recrystallisation behaviour in the shot peened deformed layer was more obvious. Based on the results of line profile analysis, the recrystallisation activation energy and microstrain relaxation energy were calculated. In addition, after isothermal annealing, the depth distribution of domain size in the deformed layer was also investigated and discussed in details. According to the analysis, the results showed that the thermostability of S30432 shot peened surface layer was relatively stable when the annealing temperature was below 650 degrees C.
Uploads
Papers by Vincent Ji