The effects of Yb/Zr micro-alloying on the microstructure,mechanical properties,and corrosion resistance of an Al-Zn-Mg-Cu alloy were systematically investigated.Upon the addition of Yb/Zr to the Al-Zn-Mg-Cu alloy,the...The effects of Yb/Zr micro-alloying on the microstructure,mechanical properties,and corrosion resistance of an Al-Zn-Mg-Cu alloy were systematically investigated.Upon the addition of Yb/Zr to the Al-Zn-Mg-Cu alloy,the grain boundaries were pinned by high-density nanosized Al_(3)(Yb,Zr)precipitates during extrusion deformation,consequently,the average grain size was significantly reduced from 232.7μm to 3.2μm.This grain refinement contributed substantially to the improvement in both strength and elongation.The ultimate tensile strength,yield strength,and elongation of the Yb/Zr modified alloy increased to 705.3 MPa,677.6 MPa,and 8.7%,respectively,representing enhancements of 16.2%,19.3%,and 112.2%compared to the unmodified alloy.Moreover,the distribution of MgZn_(2)phases along grain boundaries became more discontinuous in the Yb/Zr modified alloy,which effectively retarded the propagation of intergranular corrosion and improved the corrosion resistance.展开更多
In this research,a series of biaxial compression and biaxial fatigue tests were conducted to investigate the mechanical behaviors of marble and sandstone under biaxial confinements.Experimental results demonstrate tha...In this research,a series of biaxial compression and biaxial fatigue tests were conducted to investigate the mechanical behaviors of marble and sandstone under biaxial confinements.Experimental results demonstrate that the biaxial compressive strength of rocks under biaxial compression increases firstly,and subsequently decreases with increase of the intermediate principal stress.The fatigue failure characteristics of the rocks in biaxial fatigue tests are functions of the peak value of fatigue loads,the intermediate principal stress and the rock lithology.With the increase of the peak values of fatigue loads,the fatigue lives of rocks decrease.The intermediate principal stress strengthens the resistance ability of rocks to fatigue loads except considering the strength increasing under biaxial confinements.The fatigue lives of rocks increase with the increase of the intermediate principal stress under the same ratio of the fatigue load and their biaxial compressive strength.The acoustic emission(AE)and fragments studies showed that the sandstone has higher ability to resist the fatigue loads compared to the marble,and the marble generated a greater number of smaller fragments after fatigue failure compared to the sandstone.So,it can be inferred that the rock breaking efficiency and rock burst is higher or severer induced by fatigue loading than that induced by monotonous quasi-static loading,especially for hard rocks.展开更多
The effect of T6I6 treatment on the dynamic mechanical and microstructure behaviour of Al-Si-Mg-Cu cast alloy was investigated using split Hopkinson pressure bar(SHPB), transmission electron microscopy(TEM), and highr...The effect of T6I6 treatment on the dynamic mechanical and microstructure behaviour of Al-Si-Mg-Cu cast alloy was investigated using split Hopkinson pressure bar(SHPB), transmission electron microscopy(TEM), and highresolution transmission electron microscopy(HRTEM). Besides, the impact resistances of T6I6 and T6 motor shells of new energy vehicles made of Al-Si-Mg-Cu cast alloy were compared using a trolley crash test. The results indicated that the main strengthening-phases of the T6 peak-aged and T6I6 peak-aged alloy were GP zone and β″ precipitates. T6I6treatment can increase the density and size of β″ precipitates in peak-aged alloy and enhance both its tensile strength(σb)and elongation(δ). The dynamic toughness values of T6I6 samples are 50.34 MJ/m^(3) at 2000 s^(-1) and 177.34 MJ/m^(3) at 5000 s^(-1) which are 20% and 12% higher than those of T6 samples, respectively. Compared with a T6 shell, the overall deformation of T6I6 shell is more uniform during the crash test. At an impact momentum of 3.5×10;kg·m/s, the T6I6shell breaks down at 0.38 s which is 0.10 s later than the T6 shell.展开更多
In this paper, we simulate Localized Surface Plasmon Resonance(LSPR) absorption of periodic Au nano-ring arrays and single Au nanoparticles using the Finite Difference Time Domain(FDTD) method. We choose input plane w...In this paper, we simulate Localized Surface Plasmon Resonance(LSPR) absorption of periodic Au nano-ring arrays and single Au nanoparticles using the Finite Difference Time Domain(FDTD) method. We choose input plane waves of different wavelengths and discuss the relation between the absorption peak of the Au array and the variable external dielectric constants. It is found that the sensitivity of these sensors based on LSPR is improved compared to the common sensors and the enhancement is caused by the periodical structure. We also investigate the spectrum characteristic of a single Au nanoparticle and discuss the relation between the absorption peak and the size of the nanoparticle.展开更多
Epitaxy is usually used to produce high quality crystals with ato-mic perfection. Up to now, many semiconductor crystals of functional materials could be obtained by epitaxial growth techniques, such as molecular beam...Epitaxy is usually used to produce high quality crystals with ato-mic perfection. Up to now, many semiconductor crystals of functional materials could be obtained by epitaxial growth techniques, such as molecular beam epitaxy, chemical vapor deposition, and liquid-phase epitaxy. However, these techniques are expensive, sophisticated, and not compatible with large area production. For solution-based deposition of epitaxial films such as hydrothermal processing [1], chemical bath deposition [2-3], and electrodeposition [4-5], specific conditions such as high temperature and pressure, or conducting substrates are commonly needed. Since single crystal epitaxial films have superior electronic and optical properties compared to amorphous and polycrystalline films due to absence of high-angle grain boundaries, searching for simple, rapid and inexpensive technique to grow epitaxial films is highly desired.展开更多
An air channel inside a silver metal film is usually used as a typical Channel Plasmon Polariton(CPP) waveguide. This paper presents research on the basic properties of this waveguide using the Finite Difference Time ...An air channel inside a silver metal film is usually used as a typical Channel Plasmon Polariton(CPP) waveguide. This paper presents research on the basic properties of this waveguide using the Finite Difference Time Domain(FDTD) method. The relationship between transmission power and structure of the waveguide is investigated. The simulation results show that the subwavelength trapezoidal CPP waveguide is superior to the rectangle CPP waveguide for controlling SPP radiation loss and enhancing the transmitted power. As a result, if the rectangle CPP waveguide is replaced by a trapezoidal CPP waveguide in certain integrated optical devices, their performance may be improved.展开更多
基金Project(51501228)supported by the National Natural Science Foundation of ChinaProject(202109)supported by the Open Sharing Fund for the Large-scale Instruments and Equipments of Central South University,China。
文摘The effects of Yb/Zr micro-alloying on the microstructure,mechanical properties,and corrosion resistance of an Al-Zn-Mg-Cu alloy were systematically investigated.Upon the addition of Yb/Zr to the Al-Zn-Mg-Cu alloy,the grain boundaries were pinned by high-density nanosized Al_(3)(Yb,Zr)precipitates during extrusion deformation,consequently,the average grain size was significantly reduced from 232.7μm to 3.2μm.This grain refinement contributed substantially to the improvement in both strength and elongation.The ultimate tensile strength,yield strength,and elongation of the Yb/Zr modified alloy increased to 705.3 MPa,677.6 MPa,and 8.7%,respectively,representing enhancements of 16.2%,19.3%,and 112.2%compared to the unmodified alloy.Moreover,the distribution of MgZn_(2)phases along grain boundaries became more discontinuous in the Yb/Zr modified alloy,which effectively retarded the propagation of intergranular corrosion and improved the corrosion resistance.
基金Projects(51774326,41807259)supported by the National Natural Science Foundation of ChinaProject(MDPC201917)supported by Mining Disaster Prevention and Control Ministry Key Laboratory at Shandong University of Science and Technology,China。
文摘In this research,a series of biaxial compression and biaxial fatigue tests were conducted to investigate the mechanical behaviors of marble and sandstone under biaxial confinements.Experimental results demonstrate that the biaxial compressive strength of rocks under biaxial compression increases firstly,and subsequently decreases with increase of the intermediate principal stress.The fatigue failure characteristics of the rocks in biaxial fatigue tests are functions of the peak value of fatigue loads,the intermediate principal stress and the rock lithology.With the increase of the peak values of fatigue loads,the fatigue lives of rocks decrease.The intermediate principal stress strengthens the resistance ability of rocks to fatigue loads except considering the strength increasing under biaxial confinements.The fatigue lives of rocks increase with the increase of the intermediate principal stress under the same ratio of the fatigue load and their biaxial compressive strength.The acoustic emission(AE)and fragments studies showed that the sandstone has higher ability to resist the fatigue loads compared to the marble,and the marble generated a greater number of smaller fragments after fatigue failure compared to the sandstone.So,it can be inferred that the rock breaking efficiency and rock burst is higher or severer induced by fatigue loading than that induced by monotonous quasi-static loading,especially for hard rocks.
基金Projects(52075166, 51875197) supported by the National Natural Science Foundation of ChinaProjects(2019RS2064,2019GK5043) supported by the Science and Technology Planning Project of Hunan Province,China。
文摘The effect of T6I6 treatment on the dynamic mechanical and microstructure behaviour of Al-Si-Mg-Cu cast alloy was investigated using split Hopkinson pressure bar(SHPB), transmission electron microscopy(TEM), and highresolution transmission electron microscopy(HRTEM). Besides, the impact resistances of T6I6 and T6 motor shells of new energy vehicles made of Al-Si-Mg-Cu cast alloy were compared using a trolley crash test. The results indicated that the main strengthening-phases of the T6 peak-aged and T6I6 peak-aged alloy were GP zone and β″ precipitates. T6I6treatment can increase the density and size of β″ precipitates in peak-aged alloy and enhance both its tensile strength(σb)and elongation(δ). The dynamic toughness values of T6I6 samples are 50.34 MJ/m^(3) at 2000 s^(-1) and 177.34 MJ/m^(3) at 5000 s^(-1) which are 20% and 12% higher than those of T6 samples, respectively. Compared with a T6 shell, the overall deformation of T6I6 shell is more uniform during the crash test. At an impact momentum of 3.5×10;kg·m/s, the T6I6shell breaks down at 0.38 s which is 0.10 s later than the T6 shell.
基金supported by the Major State Basic Research and Development Program（973 Program） （2006CB302900） National Nature Science Foundation of China（60772026）.
文摘In this paper, we simulate Localized Surface Plasmon Resonance(LSPR) absorption of periodic Au nano-ring arrays and single Au nanoparticles using the Finite Difference Time Domain(FDTD) method. We choose input plane waves of different wavelengths and discuss the relation between the absorption peak of the Au array and the variable external dielectric constants. It is found that the sensitivity of these sensors based on LSPR is improved compared to the common sensors and the enhancement is caused by the periodical structure. We also investigate the spectrum characteristic of a single Au nanoparticle and discuss the relation between the absorption peak and the size of the nanoparticle.
文摘Epitaxy is usually used to produce high quality crystals with ato-mic perfection. Up to now, many semiconductor crystals of functional materials could be obtained by epitaxial growth techniques, such as molecular beam epitaxy, chemical vapor deposition, and liquid-phase epitaxy. However, these techniques are expensive, sophisticated, and not compatible with large area production. For solution-based deposition of epitaxial films such as hydrothermal processing [1], chemical bath deposition [2-3], and electrodeposition [4-5], specific conditions such as high temperature and pressure, or conducting substrates are commonly needed. Since single crystal epitaxial films have superior electronic and optical properties compared to amorphous and polycrystalline films due to absence of high-angle grain boundaries, searching for simple, rapid and inexpensive technique to grow epitaxial films is highly desired.
基金supported by the Major State Basic Research and Development Program of China （973 Program） （2006CB302900） National Nature Science Foundation of China（ 60772026）.
文摘An air channel inside a silver metal film is usually used as a typical Channel Plasmon Polariton(CPP) waveguide. This paper presents research on the basic properties of this waveguide using the Finite Difference Time Domain(FDTD) method. The relationship between transmission power and structure of the waveguide is investigated. The simulation results show that the subwavelength trapezoidal CPP waveguide is superior to the rectangle CPP waveguide for controlling SPP radiation loss and enhancing the transmitted power. As a result, if the rectangle CPP waveguide is replaced by a trapezoidal CPP waveguide in certain integrated optical devices, their performance may be improved.
