Multilayered Ti-Al based intermetallic sheets were fabricated by sintering alternately layered titanium and aluminum foils.The microstructure and phase formation of the obtained sheets under different sintering condit...Multilayered Ti-Al based intermetallic sheets were fabricated by sintering alternately layered titanium and aluminum foils.The microstructure and phase formation of the obtained sheets under different sintering conditions were evaluated by various techniques.The results reveal that when the sintering temperature is above the melting point of aluminum,the self-propagating high-temperature synthesis reaction occurs between Ti and Al,and forms various phases of Ti-based solid solutions including α-Ti Ti3Al,TiAl,TiAl2 and α-Ti including TiAl3,etc.When the sintering time increased,Ti-based solid solution,TiAl2 and TiAl3 disappeared gradually,and the sheet containing Ti3Al and TiAl phases in a multilayered structure formed finally.A lot of voids were also observed in the sintered structures,which were caused by the melting Al,Kirkendall effect and the difference of molar volumes between reactants and products.The voids were eliminated and a dense sample was obtained by the following hot press.展开更多
To investigate the effects of Al-Ti-B-RE grain refiner on microstructure and mechanical properties of Al-7.0Si-0.55Mg （A357） alloy, some novel Al-7.0Si-0.55Mg alloys added with different amount of Al-STi-1B-RE grain...To investigate the effects of Al-Ti-B-RE grain refiner on microstructure and mechanical properties of Al-7.0Si-0.55Mg （A357） alloy, some novel Al-7.0Si-0.55Mg alloys added with different amount of Al-STi-1B-RE grain refiner with different RE composition were prepared by vacuum-melting. The microstructure and fracture behavior of the AI-7.0Si-0.55Mg alloys with the grain refiners were observed by X-ray diffraction （XRD）, optical microscopy （OM）, scanning electron microscopy （SEM）, and the mechanical properties of the alloys were tested in mechanical testing machine at room temperature. The observation of AI-Ti-B-RE morphology and internal structure of the particles reveals that it exhibits a TiAl3/Ti2Al20RE core-shell structure via heterogeneous TiB2 nuclei. The tensile strength of Al-7.0Si-0.55Mg alloys with Al-5Ti-1B-3.0RE grain refiner reaches the peak value at the same addition （0.2%） of grain refiner.展开更多
Different proportions of commercial 2024 aluminum alloy powder and FeNiCrCoA13 high entropy alloy （HEA） powder were ball-milled （BM） for different time. The powder was consolidated by hot extrusion method. The mic...Different proportions of commercial 2024 aluminum alloy powder and FeNiCrCoA13 high entropy alloy （HEA） powder were ball-milled （BM） for different time. The powder was consolidated by hot extrusion method. The microstructures of the milled powder and bulk alloy were examined by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Mechanical properties of the extruded alloy were examined by mechanical testing machine. The results show that after BM, the particle size and microstructures of the mixed alloy powder change obviously. After 48 h BM, the average size of mixed powder is about 30 nm, and then after hot extrusion, the average size of grains reaches about 70 rim. The compressive strength of the extruded alloy reaches 710 MPa under certain conditions of milling time and composition. As a result of the identification of the nano-/micro-strueture-property relationship of the samples, such high strength is attributed mainly to the nanocrystalline grains of a（Al） and nanoscaled FeNiCrCoAl3 particles, and the fine secondary phase of Al2Cu and Fe-rich phases.展开更多
基金Project (2010DFA51650) supported by the Ministry of Science and Technology of China
文摘Multilayered Ti-Al based intermetallic sheets were fabricated by sintering alternately layered titanium and aluminum foils.The microstructure and phase formation of the obtained sheets under different sintering conditions were evaluated by various techniques.The results reveal that when the sintering temperature is above the melting point of aluminum,the self-propagating high-temperature synthesis reaction occurs between Ti and Al,and forms various phases of Ti-based solid solutions including α-Ti Ti3Al,TiAl,TiAl2 and α-Ti including TiAl3,etc.When the sintering time increased,Ti-based solid solution,TiAl2 and TiAl3 disappeared gradually,and the sheet containing Ti3Al and TiAl phases in a multilayered structure formed finally.A lot of voids were also observed in the sintered structures,which were caused by the melting Al,Kirkendall effect and the difference of molar volumes between reactants and products.The voids were eliminated and a dense sample was obtained by the following hot press.
基金Project(2012CB619503)supported by the Natioanl Basic Research Program of ChinaProject(2013AA031001)supported by the National High-tech Research and Development Program of ChinaProject(2012DFA50630)supported by the International Science&Technology Cooperation Program of China
文摘To investigate the effects of Al-Ti-B-RE grain refiner on microstructure and mechanical properties of Al-7.0Si-0.55Mg （A357） alloy, some novel Al-7.0Si-0.55Mg alloys added with different amount of Al-STi-1B-RE grain refiner with different RE composition were prepared by vacuum-melting. The microstructure and fracture behavior of the AI-7.0Si-0.55Mg alloys with the grain refiners were observed by X-ray diffraction （XRD）, optical microscopy （OM）, scanning electron microscopy （SEM）, and the mechanical properties of the alloys were tested in mechanical testing machine at room temperature. The observation of AI-Ti-B-RE morphology and internal structure of the particles reveals that it exhibits a TiAl3/Ti2Al20RE core-shell structure via heterogeneous TiB2 nuclei. The tensile strength of Al-7.0Si-0.55Mg alloys with Al-5Ti-1B-3.0RE grain refiner reaches the peak value at the same addition （0.2%） of grain refiner.
基金Project(2012CB619503)supported by the Nation Basic Research Program of ChinaProject(2013AA031001)supported by the National High Technology Research and Development Program of ChinaProject(2012DFA50630)supported by the International Science&Technology Cooperation Program of China
文摘Different proportions of commercial 2024 aluminum alloy powder and FeNiCrCoA13 high entropy alloy （HEA） powder were ball-milled （BM） for different time. The powder was consolidated by hot extrusion method. The microstructures of the milled powder and bulk alloy were examined by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Mechanical properties of the extruded alloy were examined by mechanical testing machine. The results show that after BM, the particle size and microstructures of the mixed alloy powder change obviously. After 48 h BM, the average size of mixed powder is about 30 nm, and then after hot extrusion, the average size of grains reaches about 70 rim. The compressive strength of the extruded alloy reaches 710 MPa under certain conditions of milling time and composition. As a result of the identification of the nano-/micro-strueture-property relationship of the samples, such high strength is attributed mainly to the nanocrystalline grains of a（Al） and nanoscaled FeNiCrCoAl3 particles, and the fine secondary phase of Al2Cu and Fe-rich phases.
