The interaction between Zn-AI eutectic alloy and Al203p/6061AI composites in the vacuum furnace was investigated. Great attention has been paid to the elements diffusion, the microstructure and formation of the interf...The interaction between Zn-AI eutectic alloy and Al203p/6061AI composites in the vacuum furnace was investigated. Great attention has been paid to the elements diffusion, the microstructure and formation of the interface between Zn-AI eutectic alloy and Al2O3p/6061AI composites. Experimental results show that Zn-AI eutectic alloy has a good wetting ability to Al2O3p/6061 Al composites and the wetting angle decreases with increasing the temperature in vacuum. After the interaction, an interaction layer forms between Zn-AI alloy and Al2O3p/6061 Al composites. The phases in the interaction layer mainly consist of α-AI(Zn), Al2O3 and CuZn5 resulted from the diffusion of elements from the Zn-AI alloy. Several porosities distribute in the region near the interface of the Zn-AI alloy/interaction layer. The amount of shrinkage voids in the interacting layer is relevant to the penetration of Zn element into Al2O3p/6061Al composites which is a function of temperature. So it is necessary to lower heating temperature in order to limit the Zn penetration.展开更多
The interfacial microstructure of Al 2O 3 short fibre reinforced Al 5.5Zn matrix composite was studied using transmission electron microscope (TEM) in this ...The interfacial microstructure of Al 2O 3 short fibre reinforced Al 5.5Zn matrix composite was studied using transmission electron microscope (TEM) in this paper.Experimental results show that there exist a diffusional layer with a wide thickness range and a third phase in the fibre/matrix interface,resulting from Al/SiO 2 reaction.Some of the reduced silicon atoms adhere to the fibre/matrix interface and nucleate to form the elemental eutectic silicon,and the others diffuse into the Al/Zn melt and form the diffusional layer.The complexity of the interfacial microstructure may result from the different solidification conditions between the regions in the melt because of the non uniformity of the fibre distribution and orientation in the preform.展开更多
The superplasticity of an Al203p/6061Al composite, fabricated by powder metallurgy techniques, has been investigated. Instead of any special thermomechanical processing or hot rolling, simple ...The superplasticity of an Al203p/6061Al composite, fabricated by powder metallurgy techniques, has been investigated. Instead of any special thermomechanical processing or hot rolling, simple hot extrusion has been employed to obtain a fine grained structure before superplastic testing. Superplastic tensile tests were performed at strain rates ranging from 10-2 to 10-4 s-1 and at temperatures from 833 to 893 K. A maximum elongation of 200% was achieved at a temperature of 853 K and an initial strain rate of 1.67×103 s-1. The highest value obtained for the strain rate sensitivity index (in) was 0.32. Differential scanning calorimeter was used to ascertain the possibility of any partial melting in the vicinity of optimum superplastic temperature. These results suggested that no liquid phase existed where maximum elongation was achieved and deformation took place entirely in the solid state.展开更多
文摘The interaction between Zn-AI eutectic alloy and Al203p/6061AI composites in the vacuum furnace was investigated. Great attention has been paid to the elements diffusion, the microstructure and formation of the interface between Zn-AI eutectic alloy and Al2O3p/6061AI composites. Experimental results show that Zn-AI eutectic alloy has a good wetting ability to Al2O3p/6061 Al composites and the wetting angle decreases with increasing the temperature in vacuum. After the interaction, an interaction layer forms between Zn-AI alloy and Al2O3p/6061 Al composites. The phases in the interaction layer mainly consist of α-AI(Zn), Al2O3 and CuZn5 resulted from the diffusion of elements from the Zn-AI alloy. Several porosities distribute in the region near the interface of the Zn-AI alloy/interaction layer. The amount of shrinkage voids in the interacting layer is relevant to the penetration of Zn element into Al2O3p/6061Al composites which is a function of temperature. So it is necessary to lower heating temperature in order to limit the Zn penetration.
文摘The interfacial microstructure of Al 2O 3 short fibre reinforced Al 5.5Zn matrix composite was studied using transmission electron microscope (TEM) in this paper.Experimental results show that there exist a diffusional layer with a wide thickness range and a third phase in the fibre/matrix interface,resulting from Al/SiO 2 reaction.Some of the reduced silicon atoms adhere to the fibre/matrix interface and nucleate to form the elemental eutectic silicon,and the others diffuse into the Al/Zn melt and form the diffusional layer.The complexity of the interfacial microstructure may result from the different solidification conditions between the regions in the melt because of the non uniformity of the fibre distribution and orientation in the preform.
基金This work was supported by the National Natural Science Foundation of China,under grant No.59781004.
文摘The superplasticity of an Al203p/6061Al composite, fabricated by powder metallurgy techniques, has been investigated. Instead of any special thermomechanical processing or hot rolling, simple hot extrusion has been employed to obtain a fine grained structure before superplastic testing. Superplastic tensile tests were performed at strain rates ranging from 10-2 to 10-4 s-1 and at temperatures from 833 to 893 K. A maximum elongation of 200% was achieved at a temperature of 853 K and an initial strain rate of 1.67×103 s-1. The highest value obtained for the strain rate sensitivity index (in) was 0.32. Differential scanning calorimeter was used to ascertain the possibility of any partial melting in the vicinity of optimum superplastic temperature. These results suggested that no liquid phase existed where maximum elongation was achieved and deformation took place entirely in the solid state.
