The results presented in this study were concerned with microstructures and mechanical properties of poly- crystalline Cu subjected to plastic deformation by a compression with oscillatory torsion process. Different d...The results presented in this study were concerned with microstructures and mechanical properties of poly- crystalline Cu subjected to plastic deformation by a compression with oscillatory torsion process. Different deformation parameters of the compression with oscillatory torsion process were adopted to study their effects on the microstructure and mechanical properties. The deformed microstructure was characterized quantitatively by electron backscattered diffraction （EBSD） and scanning transmission electron microscopy （STEM）. Mechanical properties were determined on an MTS QTest/10 machine equipped with digital image correlation. From the experimental results, processes performed at high compression speed and high torsion frequency are recommended for refining the grain size. The size of structure elements, such as average grain size （D） and subgrain size （d）, reached 0.42 μm and 0.30 μm, respectively, and the fraction of high angle boundaries was 35% when the sample was deformed at a torsion frequency f = 1.6 Hz and compression rate v= 0.04 mm/s. These deformation parameters led to an improvement in the strength properties. The material exhibited an ultimate tensile strength （UTS） of 434 MPa and a yield strength （YS） of 418 MPa. These values were about two times greater than those of the initial state.展开更多
The microstructure and texture in a commercially processed AI-6 wt% Cu-0.4 wt% Zr （Suprall00） aluminium alloy have been investigated after annealing and hot tensile straining at 450℃, using a field emission gun sca...The microstructure and texture in a commercially processed AI-6 wt% Cu-0.4 wt% Zr （Suprall00） aluminium alloy have been investigated after annealing and hot tensile straining at 450℃, using a field emission gun scanning electron microscope （SEM） and electron backscatter diffraction （EBSD）. The microstructure of commercially processed alloy had a relatively large fraction of high angle grain boundaries （HAGBs） which were aligned parallel to the rolling direction, and a strong texture. Annealing at 450℃ led to an increase in the fraction of HAGBs and to an increase in HAGB spacing and these changes were progressively enhanced by subsequent tensile deformation. The increasing fraction of HAGBs was due to the annihilation of low angle grain boundaries （LAGBs）. A sharpening of texture during annealing was attributed to preferential textural growth, and the reduction of texture at higher tensile strains led to the development of superplastic behaviour. The present work supports the view that the evolution of the fine grain microstructure during the high temperature straining of SuprallO0 is primarily due to the accumulation of a large area of grain boundary during the initial thermomechanical processing, and does not involve any unusual restoration processes.展开更多
基金supported by the Polish Ministry of Science and Higher Education under research project No. N N507 373435
文摘The results presented in this study were concerned with microstructures and mechanical properties of poly- crystalline Cu subjected to plastic deformation by a compression with oscillatory torsion process. Different deformation parameters of the compression with oscillatory torsion process were adopted to study their effects on the microstructure and mechanical properties. The deformed microstructure was characterized quantitatively by electron backscattered diffraction （EBSD） and scanning transmission electron microscopy （STEM）. Mechanical properties were determined on an MTS QTest/10 machine equipped with digital image correlation. From the experimental results, processes performed at high compression speed and high torsion frequency are recommended for refining the grain size. The size of structure elements, such as average grain size （D） and subgrain size （d）, reached 0.42 μm and 0.30 μm, respectively, and the fraction of high angle boundaries was 35% when the sample was deformed at a torsion frequency f = 1.6 Hz and compression rate v= 0.04 mm/s. These deformation parameters led to an improvement in the strength properties. The material exhibited an ultimate tensile strength （UTS） of 434 MPa and a yield strength （YS） of 418 MPa. These values were about two times greater than those of the initial state.
基金grateful to EPSRC for financial supportvia Grant GR/R69952/01 and Super form for the supply of material
文摘The microstructure and texture in a commercially processed AI-6 wt% Cu-0.4 wt% Zr （Suprall00） aluminium alloy have been investigated after annealing and hot tensile straining at 450℃, using a field emission gun scanning electron microscope （SEM） and electron backscatter diffraction （EBSD）. The microstructure of commercially processed alloy had a relatively large fraction of high angle grain boundaries （HAGBs） which were aligned parallel to the rolling direction, and a strong texture. Annealing at 450℃ led to an increase in the fraction of HAGBs and to an increase in HAGB spacing and these changes were progressively enhanced by subsequent tensile deformation. The increasing fraction of HAGBs was due to the annihilation of low angle grain boundaries （LAGBs）. A sharpening of texture during annealing was attributed to preferential textural growth, and the reduction of texture at higher tensile strains led to the development of superplastic behaviour. The present work supports the view that the evolution of the fine grain microstructure during the high temperature straining of SuprallO0 is primarily due to the accumulation of a large area of grain boundary during the initial thermomechanical processing, and does not involve any unusual restoration processes.
