With the aim to further improve the mechanical properties of Mg-A1-RE-based alloy, Mg-3.0Al-1.8Ce-0.3Y-0.2Mn alloy was prepared by high-pressure die-casting technique. The microstructure, thermal stability of intermet...With the aim to further improve the mechanical properties of Mg-A1-RE-based alloy, Mg-3.0Al-1.8Ce-0.3Y-0.2Mn alloy was prepared by high-pressure die-casting technique. The microstructure, thermal stability of intermetallic phases and mechanical properties were investigated. The results show that the alloy is composed of fine primary a-Mg dendrites and eutectic in the interdendritic regions. The intermetallic phases in eutectic are Aln（Ce,Y）3 and A12（Ce,Y） with the former being the dominant one. The thermal stability of Al11（ce,Y）3 is conditioned. It is basically stable at temperature up to 200℃ within 800 h, while most of the Al11（Ce,Y）3 intermetallics transform to A12（Ce,Y） at higher temperature of 450 ℃ for 800 h. The alloy exhibits remarkably improved strength both at room temperature and 200℃, which is mainly attributed to the reinforcement of dendrite boundaries with Alll（Ce,Y）3 intermetallics, small dendritic arm spacing effect as well as the solid solution strengthening with Y element.展开更多
Mg-A1 mixed oxides with different Mg/A1 molar ratio were prepared by thermal decomposition of hydrotalcite- like precursors at 500 ℃ for 5.0 h and used as catalysts for the transesterification of diphenyl carbonate w...Mg-A1 mixed oxides with different Mg/A1 molar ratio were prepared by thermal decomposition of hydrotalcite- like precursors at 500 ℃ for 5.0 h and used as catalysts for the transesterification of diphenyl carbonate with 1,4-butanediol to synthesize high-molecular-weight poly（butylene carbonate） （PBC）. The structure-activity correlations of these catalysts in this transesterification process were discussed by means of various characterization techniques. It was found that the chain growth for the formation of PBC can only be obtained through connecting -OH and -OC（C）OC6H5 end-group upon removing the generated phenol, and the sample with Mg/A1 molar ratio of 4.0 exhibited the best catalytic performance, giving PBC with Mw of 1.64 × 105 g/mol at 210℃ for 3.0 h. This excellent activity depended mainly on the specific surface area and basicity rather than pore structure or crystallite size of MgO.展开更多
The Mg-A1 hydrogen storage alloy was suc- cessfully prepared by combustion synthesis （CS） method. The formation of alloy phases during the CS process was studied using X-ray diffraction （XRD）, scanning electron mi...The Mg-A1 hydrogen storage alloy was suc- cessfully prepared by combustion synthesis （CS） method. The formation of alloy phases during the CS process was studied using X-ray diffraction （XRD）, scanning electron microscope （SEM）, and differential scanning calorimetry （DSC）. When the time increases from 0, 0.5, 1.0 to 2.0 h at 733 K, the products are Mg and A1; Mg2A13, Mg and A1; Mgl7All2, Mg2A13; and Mg; and eventually only MgI7A112, respectively. Combined with three peaks in the DSC traces, it is concluded that the formation of MglyAll2 during the CS includes three processes, namely, the formation of MgzA13 first; then the unsaturated solid solution, MglvAla2; and finally the complete MglvA112 alloy. The formation of MgzA13 prior to MglvA112 in this work is different from those prepared by mechanical alloying. This is thought to be related to the instant high temperature during the ther- mal explosion of CS.展开更多
基金Project (HEUCFR1128) supported by the Fundamental Research Funds for the Central Universities,ChinaProject (2010AA4BE031)supported by the Key Project of Science and Technology of Harbin City,China+1 种基金Projects (20100471015,20100471046) supported by the China Postdoctoral Science FoundationProject (LBH-Z09217) supported by the Heilongjiang Postdoctorial Fund,China
文摘With the aim to further improve the mechanical properties of Mg-A1-RE-based alloy, Mg-3.0Al-1.8Ce-0.3Y-0.2Mn alloy was prepared by high-pressure die-casting technique. The microstructure, thermal stability of intermetallic phases and mechanical properties were investigated. The results show that the alloy is composed of fine primary a-Mg dendrites and eutectic in the interdendritic regions. The intermetallic phases in eutectic are Aln（Ce,Y）3 and A12（Ce,Y） with the former being the dominant one. The thermal stability of Al11（ce,Y）3 is conditioned. It is basically stable at temperature up to 200℃ within 800 h, while most of the Al11（Ce,Y）3 intermetallics transform to A12（Ce,Y） at higher temperature of 450 ℃ for 800 h. The alloy exhibits remarkably improved strength both at room temperature and 200℃, which is mainly attributed to the reinforcement of dendrite boundaries with Alll（Ce,Y）3 intermetallics, small dendritic arm spacing effect as well as the solid solution strengthening with Y element.
基金financially supported by the National Key Technology Pillar Program(No.2013BAC11B05)Key Research and Innovation Program of Jiangsu Province(No.BE2015055)the Science&Technology Pillar Program in Sichuan Province(No.2016GZ0228)
文摘Mg-A1 mixed oxides with different Mg/A1 molar ratio were prepared by thermal decomposition of hydrotalcite- like precursors at 500 ℃ for 5.0 h and used as catalysts for the transesterification of diphenyl carbonate with 1,4-butanediol to synthesize high-molecular-weight poly（butylene carbonate） （PBC）. The structure-activity correlations of these catalysts in this transesterification process were discussed by means of various characterization techniques. It was found that the chain growth for the formation of PBC can only be obtained through connecting -OH and -OC（C）OC6H5 end-group upon removing the generated phenol, and the sample with Mg/A1 molar ratio of 4.0 exhibited the best catalytic performance, giving PBC with Mw of 1.64 × 105 g/mol at 210℃ for 3.0 h. This excellent activity depended mainly on the specific surface area and basicity rather than pore structure or crystallite size of MgO.
基金financially supported by the National Natural Science Foundation of China(Nos.51071085 and 51171079)Specialized Research Fund for the Doctoral Program of High Education(No.20093221110008)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘The Mg-A1 hydrogen storage alloy was suc- cessfully prepared by combustion synthesis （CS） method. The formation of alloy phases during the CS process was studied using X-ray diffraction （XRD）, scanning electron microscope （SEM）, and differential scanning calorimetry （DSC）. When the time increases from 0, 0.5, 1.0 to 2.0 h at 733 K, the products are Mg and A1; Mg2A13, Mg and A1; Mgl7All2, Mg2A13; and Mg; and eventually only MgI7A112, respectively. Combined with three peaks in the DSC traces, it is concluded that the formation of MglyAll2 during the CS includes three processes, namely, the formation of MgzA13 first; then the unsaturated solid solution, MglvAla2; and finally the complete MglvA112 alloy. The formation of MgzA13 prior to MglvA112 in this work is different from those prepared by mechanical alloying. This is thought to be related to the instant high temperature during the ther- mal explosion of CS.
