The Al2O3（p）/Al nano-composites were fabricated from Al-K2ZrF6-Na2B4O7 system by sonochemistry in situ reaction. The fabrication mechanisms, including high intensity ultrasonic influence on microstructures and reinf...The Al2O3（p）/Al nano-composites were fabricated from Al-K2ZrF6-Na2B4O7 system by sonochemistry in situ reaction. The fabrication mechanisms, including high intensity ultrasonic influence on microstructures and reinforcement particles-aluminum matrix interface, were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The XRD results show that the component of the as-prepared composites is Al2O3 reinforcement. The SEM analysis results indicate that Al2O3 particles are uniformly distributed in the aluminum matrix. The TEM results show that the morphologies of Al2O3 particles present in nearly sphere-shape, the sizes are in the range of 20-100 nm, and the interfaces are net and no interfacial outgrowth is observed. Analysis with secondary development Image-J software shows that Al2O3 recoveries are firstly improved and then decreased with increasing ultrasonic power. When the power is 0.4 kW, the distribution is the best, and a maximum number of particles are obtained. The reaction mechanisms were investigated.展开更多
Copper matrix composites(CMCs)offer promising applications by combining the functional characteristics of copper with composite phases.With the rapid advancement in aerospace,microelectronics,and intelligent terminal ...Copper matrix composites(CMCs)offer promising applications by combining the functional characteristics of copper with composite phases.With the rapid advancement in aerospace,microelectronics,and intelligent terminal engineering,the demand for CMCs with superior mechanical and electrical properties has become increasingly critical.This paper reviews the design principles,preparation methods,microstructures and properties of some typical CMCs.The existing form of composite phases in the Cu matrix and their effects on microstructure evolution and comprehensive properties are summarised.Key underlying mechanisms governing these enhancements are discussed.The results provide a systematic understanding of the relationship between reinforcement phases and properties,offering insights for the future development of CMCs aimed to achieve much better comprehensive properties.The paper concludes by outlining the development trends and future outlook for the application of CMCs.展开更多
Three new complex borate compounds K7CaBi2B15O30, K7CaLa2B15 O30 and K7BaBi2B15O30 have been synthesized by the high-temperature solution method.K7CaLa2B15O30and K7CaBi2B15O30crystallize in the chiral trigonal space g...Three new complex borate compounds K7CaBi2B15O30, K7CaLa2B15 O30 and K7BaBi2B15O30 have been synthesized by the high-temperature solution method.K7CaLa2B15O30and K7CaBi2B15O30crystallize in the chiral trigonal space group R32, while K7BaBi2B15O30 crystallizes in the noncentrosymmetric orthorhombic polar space group Pca21. All of the title compounds have similar three-dimensional crystal structures, which are composed of isolated B5 O10 groups and LaO6 or BiO6 octahedra, and K^+, Ca^2+, and Ba^2+ cations fill into the cavities to keep charge balance. Based on our research, in the system of K7 MIIRE2 B15O30(MII= Ca, Sr,Ba, Zn, Cd, Pb, K/RE0.5;RE = Sc, Y, La, Gd, Lu, Bi),K7BaBi2B15O30 is unique and crystallizes in a different space group, which enriches the structural chemistry of borate.Detailed structural analyses indicate that the structural variation is due to the difference in size and coordination number of the alkaline-earth metal cations. Besides, UV-Vis-NIR spectroscopy analysis and the second-harmonic generation(SHG) measurement on the powder samples show that K7CaBi2B15O30 exhibits a UV cutoff edge(about 282 nm) and a moderate SHG response(about 0.6 × KDP). In addition,thermal analysis and infrared spectroscopy were also presented. To better understand the structure-property relationships of the title compounds, the first-principles calculations have been performed.展开更多
The classical Hashin-Shtrikman variational principle was re-generalized to the heterogeneous piezoelectric materials.The auxiliary problem is very much simplified by selecting the reference medium as a linearly isotro...The classical Hashin-Shtrikman variational principle was re-generalized to the heterogeneous piezoelectric materials.The auxiliary problem is very much simplified by selecting the reference medium as a linearly isotropic elastic medium.The electromechanical fields in the inhomogeneous piezoelectrics are simulated by introducing into the homogeneous reference medium certain eigenstresses and eigen electric fields.A closed-form solution can be obtained for the disturbance fields,which is convenient for the manipulation of the energy functional.As an application,a two-phase piezoelectric composite with nonpiezoelectric matrix is considered.Expressions of upper and lower bounds for the overall electromechanical moduli of the composite can be developed.These bounds are shown better than the Voigt-Reuss type ones.展开更多
基金Project (50971066) supported by the National Natural Science Foundation of ChinaProject (20070299004) supported by the Research Fund for the Doctoral Program of Higher Education of China+1 种基金Project (2008-46) supported by the Jiangsu Provincial ‘333’ Project of training the High-level Talents Foundation, ChinaProject (BE2009127) supported by the Jiangsu Provincial Science Supporting Item, China
文摘The Al2O3（p）/Al nano-composites were fabricated from Al-K2ZrF6-Na2B4O7 system by sonochemistry in situ reaction. The fabrication mechanisms, including high intensity ultrasonic influence on microstructures and reinforcement particles-aluminum matrix interface, were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The XRD results show that the component of the as-prepared composites is Al2O3 reinforcement. The SEM analysis results indicate that Al2O3 particles are uniformly distributed in the aluminum matrix. The TEM results show that the morphologies of Al2O3 particles present in nearly sphere-shape, the sizes are in the range of 20-100 nm, and the interfaces are net and no interfacial outgrowth is observed. Analysis with secondary development Image-J software shows that Al2O3 recoveries are firstly improved and then decreased with increasing ultrasonic power. When the power is 0.4 kW, the distribution is the best, and a maximum number of particles are obtained. The reaction mechanisms were investigated.
基金support by the Key-Area Research and Development Program of Guangdong Province,China(No.2024B0101080003)Hunan Provincial Natural Science Foundation of China(No.2024JJ2076)grants from the State Key Laboratory of Powder Metallurgy,Central South University,China.
文摘Copper matrix composites(CMCs)offer promising applications by combining the functional characteristics of copper with composite phases.With the rapid advancement in aerospace,microelectronics,and intelligent terminal engineering,the demand for CMCs with superior mechanical and electrical properties has become increasingly critical.This paper reviews the design principles,preparation methods,microstructures and properties of some typical CMCs.The existing form of composite phases in the Cu matrix and their effects on microstructure evolution and comprehensive properties are summarised.Key underlying mechanisms governing these enhancements are discussed.The results provide a systematic understanding of the relationship between reinforcement phases and properties,offering insights for the future development of CMCs aimed to achieve much better comprehensive properties.The paper concludes by outlining the development trends and future outlook for the application of CMCs.
基金supported by the West Light Foundation of the CAS(2016-YJRC-2 and 2015 XBQN-B-11)the National Natural Science Foundation of China(51602341 and 91622107)+2 种基金the Natural Science Foundation of Xinjiang(2016D01B061)Tianshan Innovation Team Program(2018D14001)Key research project of Frontier Science of CAS(QYZDB-SSW-JSC049)
文摘Three new complex borate compounds K7CaBi2B15O30, K7CaLa2B15 O30 and K7BaBi2B15O30 have been synthesized by the high-temperature solution method.K7CaLa2B15O30and K7CaBi2B15O30crystallize in the chiral trigonal space group R32, while K7BaBi2B15O30 crystallizes in the noncentrosymmetric orthorhombic polar space group Pca21. All of the title compounds have similar three-dimensional crystal structures, which are composed of isolated B5 O10 groups and LaO6 or BiO6 octahedra, and K^+, Ca^2+, and Ba^2+ cations fill into the cavities to keep charge balance. Based on our research, in the system of K7 MIIRE2 B15O30(MII= Ca, Sr,Ba, Zn, Cd, Pb, K/RE0.5;RE = Sc, Y, La, Gd, Lu, Bi),K7BaBi2B15O30 is unique and crystallizes in a different space group, which enriches the structural chemistry of borate.Detailed structural analyses indicate that the structural variation is due to the difference in size and coordination number of the alkaline-earth metal cations. Besides, UV-Vis-NIR spectroscopy analysis and the second-harmonic generation(SHG) measurement on the powder samples show that K7CaBi2B15O30 exhibits a UV cutoff edge(about 282 nm) and a moderate SHG response(about 0.6 × KDP). In addition,thermal analysis and infrared spectroscopy were also presented. To better understand the structure-property relationships of the title compounds, the first-principles calculations have been performed.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11072179 and 11090334)Shanghai Leading Academic Discipline Project (Grant No. B302)
文摘The classical Hashin-Shtrikman variational principle was re-generalized to the heterogeneous piezoelectric materials.The auxiliary problem is very much simplified by selecting the reference medium as a linearly isotropic elastic medium.The electromechanical fields in the inhomogeneous piezoelectrics are simulated by introducing into the homogeneous reference medium certain eigenstresses and eigen electric fields.A closed-form solution can be obtained for the disturbance fields,which is convenient for the manipulation of the energy functional.As an application,a two-phase piezoelectric composite with nonpiezoelectric matrix is considered.Expressions of upper and lower bounds for the overall electromechanical moduli of the composite can be developed.These bounds are shown better than the Voigt-Reuss type ones.
