Wedge-shaped copper casting experiment was conducted to study the engulfment behavior of TiB2 particle and the interaction between particle or cluster and the solid/liquid front in commercial pure aluminum matrix. The...Wedge-shaped copper casting experiment was conducted to study the engulfment behavior of TiB2 particle and the interaction between particle or cluster and the solid/liquid front in commercial pure aluminum matrix. The experimental results show that the particle size distribution obeys two separate systems in the whole wedge-cast sample. Furthermore, it is found that the big clusters are pushed to the center of the wedge shaped sample and the single particle or small clusters consisting of few particles are engulfed into the α-Al in the area of the sample edge. The cluster degree of particles varies in different areas, and its value is 0.2 and 0.6 for the cluster fraction in the edge and in the center of the wedge sample, respectively. The cluster diameter does not obey the normal distribution but approximately obeys lognormal distribution in the present work. More importantly, in the whole sample, the particle size obeys two separate log-normal distributions.展开更多
Copper cladding aluminum(CCA)rods with the section dimensions of12mm in diameter and2mm in sheath thickness were fabricated by vertical core-filling continuous casting(VCFC)technology.The kinds and morphology of inter...Copper cladding aluminum(CCA)rods with the section dimensions of12mm in diameter and2mm in sheath thickness were fabricated by vertical core-filling continuous casting(VCFC)technology.The kinds and morphology of interfacial intermetallic compounds(IMCs)were investigated by SEM,XRD and TEM.The results showed that the interfacial structure of Cu/Al was mainly composed of layeredγ1(Cu9Al4),cellularθ(CuAl2),andα(Al)+θ(CuAl2)phases.Moreover,residual acicularε2(Cu3Al2+x)phase was observed at the Cu/Al interface.By comparing the driving force of formation forε2(Cu3Al2+x)andγ1(Cu9Al4)phases,the conclusion was drawn that theε2(Cu3Al2+x)formed firstly at the Cu/Al interface.In addition,the interfacial formation mechanism of copper cladding aluminum composites was revealed completely.展开更多
An aluminum/copper clad composite was fabricated by the casting-cold extrusion forming technology and the microstructures of the products were observed and analyzed.It is found that aluminum grains at the interface ar...An aluminum/copper clad composite was fabricated by the casting-cold extrusion forming technology and the microstructures of the products were observed and analyzed.It is found that aluminum grains at the interface are refined in the radial profiles of cone-shaped deformation zone,but the grains in the center maintain the original state and the grain size is non-uniform.A clear boundary presents between the refined area and center area.In contrast,the copper grains in the radial profiles have been significantly refined.In the center area of the copper,the grains are bigger than those at the boundary.On the surface of the deformable body,the grain size is the smallest,but with irregular grain morphology.After the product is entirely extruded,all the copper and aluminum grains are refined with small and uniform morphology.In the center area,the average diameter of aluminum grains is smaller than 5 μm,and the copper grain on the surface is about 10 μm.At the interface,the grain size is very small,with a good combination of copper and aluminum.The thickness of interface is in the range of 10-15 μm.Energy spectrum analysis shows that CuAl3 phase presents at the interface.展开更多
The main objective of this study is to enhance the strength of CNTs （carbon nanotubes） which reinforced AI matrix composites by introducing an appropriate amount of Copper（Cu） into the composite material. AI-Cu/MW...The main objective of this study is to enhance the strength of CNTs （carbon nanotubes） which reinforced AI matrix composites by introducing an appropriate amount of Copper（Cu） into the composite material. AI-Cu/MWCNTs （multi-walled carbon nanotubes） nanocomposites were produced via compaction, sintering and hot extrusion process of AI-Cu/MWCNTs powders, which were fabricated by a conventional ball mill process with AI powders and Cu-MWCNTs composite powders which were synthesized by molecular level mixing technique. Also the change of mechanical properties with different content ratio of Cu/MWCNT composite powders in A1 matrix is analyzed. It is found that the addition of the proper Cu/MWCNTs powders which are well distributed in AI matrix leads to high mechanical stiffness. The 2 wt% Cu/MWCNTs reinforced A1 composites which exhibited 3.2 times higher tensile strength and 4.4 times higher yield strength than pure AI.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51975398, 51905372)the Fund for Shanxi “1331 Project”, Chinathe 111 Project, China (No. D21003)。
文摘Wedge-shaped copper casting experiment was conducted to study the engulfment behavior of TiB2 particle and the interaction between particle or cluster and the solid/liquid front in commercial pure aluminum matrix. The experimental results show that the particle size distribution obeys two separate systems in the whole wedge-cast sample. Furthermore, it is found that the big clusters are pushed to the center of the wedge shaped sample and the single particle or small clusters consisting of few particles are engulfed into the α-Al in the area of the sample edge. The cluster degree of particles varies in different areas, and its value is 0.2 and 0.6 for the cluster fraction in the edge and in the center of the wedge sample, respectively. The cluster diameter does not obey the normal distribution but approximately obeys lognormal distribution in the present work. More importantly, in the whole sample, the particle size obeys two separate log-normal distributions.
基金Project(51274038)supported by the National Natural Science Foundation of China
文摘Copper cladding aluminum(CCA)rods with the section dimensions of12mm in diameter and2mm in sheath thickness were fabricated by vertical core-filling continuous casting(VCFC)technology.The kinds and morphology of interfacial intermetallic compounds(IMCs)were investigated by SEM,XRD and TEM.The results showed that the interfacial structure of Cu/Al was mainly composed of layeredγ1(Cu9Al4),cellularθ(CuAl2),andα(Al)+θ(CuAl2)phases.Moreover,residual acicularε2(Cu3Al2+x)phase was observed at the Cu/Al interface.By comparing the driving force of formation forε2(Cu3Al2+x)andγ1(Cu9Al4)phases,the conclusion was drawn that theε2(Cu3Al2+x)formed firstly at the Cu/Al interface.In addition,the interfacial formation mechanism of copper cladding aluminum composites was revealed completely.
基金Project(60806006) supported by the National Natural Science Foundation of China
文摘An aluminum/copper clad composite was fabricated by the casting-cold extrusion forming technology and the microstructures of the products were observed and analyzed.It is found that aluminum grains at the interface are refined in the radial profiles of cone-shaped deformation zone,but the grains in the center maintain the original state and the grain size is non-uniform.A clear boundary presents between the refined area and center area.In contrast,the copper grains in the radial profiles have been significantly refined.In the center area of the copper,the grains are bigger than those at the boundary.On the surface of the deformable body,the grain size is the smallest,but with irregular grain morphology.After the product is entirely extruded,all the copper and aluminum grains are refined with small and uniform morphology.In the center area,the average diameter of aluminum grains is smaller than 5 μm,and the copper grain on the surface is about 10 μm.At the interface,the grain size is very small,with a good combination of copper and aluminum.The thickness of interface is in the range of 10-15 μm.Energy spectrum analysis shows that CuAl3 phase presents at the interface.
文摘The main objective of this study is to enhance the strength of CNTs （carbon nanotubes） which reinforced AI matrix composites by introducing an appropriate amount of Copper（Cu） into the composite material. AI-Cu/MWCNTs （multi-walled carbon nanotubes） nanocomposites were produced via compaction, sintering and hot extrusion process of AI-Cu/MWCNTs powders, which were fabricated by a conventional ball mill process with AI powders and Cu-MWCNTs composite powders which were synthesized by molecular level mixing technique. Also the change of mechanical properties with different content ratio of Cu/MWCNT composite powders in A1 matrix is analyzed. It is found that the addition of the proper Cu/MWCNTs powders which are well distributed in AI matrix leads to high mechanical stiffness. The 2 wt% Cu/MWCNTs reinforced A1 composites which exhibited 3.2 times higher tensile strength and 4.4 times higher yield strength than pure AI.
