Copper sheet with grain size of 30-60μm was processed by plastic deformation of asymmetrical accumulative rolling-bonding(AARB)with the strain of 3.2.The effects of annealing temperature and time on microstructural e...Copper sheet with grain size of 30-60μm was processed by plastic deformation of asymmetrical accumulative rolling-bonding(AARB)with the strain of 3.2.The effects of annealing temperature and time on microstructural evolution were studied by means of electron backscattered diffraction(EBSD).EBSD grain mapping,recrystallization pole figure and grain boundary misorientation angle distribution graph were constructed,and the characteristics were assessed by microstructure,grain size,grain boundary misorientation and texture.The results show that ultra fine grains(UFG)are obtained after annealing at 250℃ for 30?40 min.When the annealing is controlled at 250℃for 40 min,the recrystallization is finished,a large number of small grains appear and most grain boundaries consist of low-angle boundaries.The character of texture is rolling texture after the recrystallization treatment,but the strength of the texture is faint.While second recrystallization happens,{110}<1ī2>+{112}<11ī> texture component disappears and turns into{122}<212>cube twin texture component.展开更多
Performance of commercial alloys can be improved greatly by severe plastic deformation, which refines grain of metals to several micrometer or sub micrometer order. During severe plastic deformation, the final size of...Performance of commercial alloys can be improved greatly by severe plastic deformation, which refines grain of metals to several micrometer or sub micrometer order. During severe plastic deformation, the final size of grain structure depends on the following factors: strain rate, total strain, deformation temperature and so on. Under a certain condition, structure cannot be infinitely refined, which means that the size of grain has a limit with the increase of total strain. Under conventional hot deformation temperature, the grain size of 7075 aluminum alloy can be refined to 12 μm, and it will not become smaller with the increase of total strain, that is to say, the limit of grain refinement is about 1 μm.展开更多
Al/Mg alloy multilayered composites were produced successfully at the lower temperature（280 C） by accumulative roll bonding（ARB） processing technique.The microstructures of Al and Mg alloy layers were characterize...Al/Mg alloy multilayered composites were produced successfully at the lower temperature（280 C） by accumulative roll bonding（ARB） processing technique.The microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy and transmission electron microscopy.Vickers hardness and three-point bending tests were conducted to investigate mechanical properties of the composites.It is found that Vickers hardness,bending strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARB pass.Delamination and crack propagation along the interface are the two main failure modes of the multilayered composite subjected to bending load.Strengthening and fracture mechanisms of the composite are analyzed.展开更多
基金Projects(50804018,50564005)supported by the National Natural Science Foundation of ChinaProject(2003E0003Z)supported by the Key Science Foundation of Yunnan Province,China+1 种基金Project(08Y0055)supported by Scientific Research Fund of Yunnan Provincial Education Department,ChinaProject(2008-055)supported by Talents Cultivation Foundation of Kunming University of Science and Technology,China
文摘Copper sheet with grain size of 30-60μm was processed by plastic deformation of asymmetrical accumulative rolling-bonding(AARB)with the strain of 3.2.The effects of annealing temperature and time on microstructural evolution were studied by means of electron backscattered diffraction(EBSD).EBSD grain mapping,recrystallization pole figure and grain boundary misorientation angle distribution graph were constructed,and the characteristics were assessed by microstructure,grain size,grain boundary misorientation and texture.The results show that ultra fine grains(UFG)are obtained after annealing at 250℃ for 30?40 min.When the annealing is controlled at 250℃for 40 min,the recrystallization is finished,a large number of small grains appear and most grain boundaries consist of low-angle boundaries.The character of texture is rolling texture after the recrystallization treatment,but the strength of the texture is faint.While second recrystallization happens,{110}<1ī2>+{112}<11ī> texture component disappears and turns into{122}<212>cube twin texture component.
文摘Performance of commercial alloys can be improved greatly by severe plastic deformation, which refines grain of metals to several micrometer or sub micrometer order. During severe plastic deformation, the final size of grain structure depends on the following factors: strain rate, total strain, deformation temperature and so on. Under a certain condition, structure cannot be infinitely refined, which means that the size of grain has a limit with the increase of total strain. Under conventional hot deformation temperature, the grain size of 7075 aluminum alloy can be refined to 12 μm, and it will not become smaller with the increase of total strain, that is to say, the limit of grain refinement is about 1 μm.
基金supported by the National Natural Science Foundation of China (Grant No. 50890173)
文摘Al/Mg alloy multilayered composites were produced successfully at the lower temperature（280 C） by accumulative roll bonding（ARB） processing technique.The microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy and transmission electron microscopy.Vickers hardness and three-point bending tests were conducted to investigate mechanical properties of the composites.It is found that Vickers hardness,bending strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARB pass.Delamination and crack propagation along the interface are the two main failure modes of the multilayered composite subjected to bending load.Strengthening and fracture mechanisms of the composite are analyzed.
