A facile and innovative method to improve bonding between the two parts of compound squeeze cast Al/Al-4.5 wt.%Cu macrocomposite bimetals was developed and its effects on microstructure and mechanical properties of th...A facile and innovative method to improve bonding between the two parts of compound squeeze cast Al/Al-4.5 wt.%Cu macrocomposite bimetals was developed and its effects on microstructure and mechanical properties of the bimetal were investigated.A special concentric groove pattern was machined on the top surface of the insert(squeeze cast Al-4.5 wt.%Cu) and its effects on heat transfer,solidification and distribution of generated stresses along the interface region of the bimetal components were simulated using ProCAST and ANSYS softwares and experimentally verified. Simulation results indicated complete melting of the tips of the surface grooves and local generation of large stress gradient fields along the interface. These are believed to result in rupture of the insert interfacial aluminum oxide layer facilitating diffusion bonding of the bimetal components. Microstructural evaluations confirmed formation of an evident transition zone along the interface region of the bimetal. Average thickness of the transition zone and tensile strength of the bimetal were significantly increased to about 375 μm and 54 MPa, respectively, by applying the surface pattern.The proposed method is an affordable and promising approach for compound squeeze casting of Al-Al macrocomposite bimetals without resort to any prior cost and time intensive chemical or coating treatments of the solid insert.展开更多
Plant organs are derived from stem cells.Once a leaf primordium initiates growth from the shoot apical meristem（SAM）,it establishes adaxial-abaxial（dorsal-ventral）polarity.This polarity essentially allows the leaf...Plant organs are derived from stem cells.Once a leaf primordium initiates growth from the shoot apical meristem（SAM）,it establishes adaxial-abaxial（dorsal-ventral）polarity.This polarity essentially allows the leaf to become a flat structure with the lamina expanding along the juxtaposition,i.e.,the middle domain,between the adaxial and abaxial domains.展开更多
基金the financial support from Iran National Science Foundation (INSF) under grant number 95822903
文摘A facile and innovative method to improve bonding between the two parts of compound squeeze cast Al/Al-4.5 wt.%Cu macrocomposite bimetals was developed and its effects on microstructure and mechanical properties of the bimetal were investigated.A special concentric groove pattern was machined on the top surface of the insert(squeeze cast Al-4.5 wt.%Cu) and its effects on heat transfer,solidification and distribution of generated stresses along the interface region of the bimetal components were simulated using ProCAST and ANSYS softwares and experimentally verified. Simulation results indicated complete melting of the tips of the surface grooves and local generation of large stress gradient fields along the interface. These are believed to result in rupture of the insert interfacial aluminum oxide layer facilitating diffusion bonding of the bimetal components. Microstructural evaluations confirmed formation of an evident transition zone along the interface region of the bimetal. Average thickness of the transition zone and tensile strength of the bimetal were significantly increased to about 375 μm and 54 MPa, respectively, by applying the surface pattern.The proposed method is an affordable and promising approach for compound squeeze casting of Al-Al macrocomposite bimetals without resort to any prior cost and time intensive chemical or coating treatments of the solid insert.
文摘Plant organs are derived from stem cells.Once a leaf primordium initiates growth from the shoot apical meristem（SAM）,it establishes adaxial-abaxial（dorsal-ventral）polarity.This polarity essentially allows the leaf to become a flat structure with the lamina expanding along the juxtaposition,i.e.,the middle domain,between the adaxial and abaxial domains.
