The superplasticity behavior of Fe-28Al, Fe-28Al-2Ti, Fe-28Al-4Ti (all composition reported in this paper are in atomic percent) alloys has been investigated by tensile testing.optical microscopy and transmission elec...The superplasticity behavior of Fe-28Al, Fe-28Al-2Ti, Fe-28Al-4Ti (all composition reported in this paper are in atomic percent) alloys has been investigated by tensile testing.optical microscopy and transmission electron mocroscopy.Tensile test were performed at 700 to 900℃ under a strain rate range of about 10-5/s to 10-2/s. Maximum strain rate sensitivity index m was found to be 0.5 and the largest elongation reached 620%. The flow activation energy was measured to be 263kJ/mol for Fe-28Al and 191kJ/ mol for Fe-28Al-2Ti, which are much lower than the creep activation energy generally observed in Fe3Al alloys. After deformation grain size became much finer from about 100 μm to 20-30μm.As combined with TEM observations, we suggested that a continuous recrystallization process took place and superplasticity may arise from this process.展开更多
A new method of getting ultrafine grain size has been investigated, which is called 'Extrusion Upsetting Multiple Processing in Sandglass Die' or 'Sandglass Extrusion' (SE). Since the shape of tested b...A new method of getting ultrafine grain size has been investigated, which is called 'Extrusion Upsetting Multiple Processing in Sandglass Die' or 'Sandglass Extrusion' (SE). Since the shape of tested billet can remain unchanged after SE, the billet can be extruded repeatedly in order to get large plastic strain. The ultrafine grain size can be obtained in the billet material due to the large plastic strain and the dynamic recrystallization during SE. The experiments on SE of Zn-5% Al alloy have been done. The SE technology, microstructures, microhardness and superplasticity of tested material after SE have been studied. The experimental results show that the equal-axial ultrafine microstructures can be introduced to the bulk test material during sandglass extrusion. The high strain rate superplasticity can be realized.展开更多
文摘The superplasticity behavior of Fe-28Al, Fe-28Al-2Ti, Fe-28Al-4Ti (all composition reported in this paper are in atomic percent) alloys has been investigated by tensile testing.optical microscopy and transmission electron mocroscopy.Tensile test were performed at 700 to 900℃ under a strain rate range of about 10-5/s to 10-2/s. Maximum strain rate sensitivity index m was found to be 0.5 and the largest elongation reached 620%. The flow activation energy was measured to be 263kJ/mol for Fe-28Al and 191kJ/ mol for Fe-28Al-2Ti, which are much lower than the creep activation energy generally observed in Fe3Al alloys. After deformation grain size became much finer from about 100 μm to 20-30μm.As combined with TEM observations, we suggested that a continuous recrystallization process took place and superplasticity may arise from this process.
基金the National Natural Science Foundation of China.
文摘A new method of getting ultrafine grain size has been investigated, which is called 'Extrusion Upsetting Multiple Processing in Sandglass Die' or 'Sandglass Extrusion' (SE). Since the shape of tested billet can remain unchanged after SE, the billet can be extruded repeatedly in order to get large plastic strain. The ultrafine grain size can be obtained in the billet material due to the large plastic strain and the dynamic recrystallization during SE. The experiments on SE of Zn-5% Al alloy have been done. The SE technology, microstructures, microhardness and superplasticity of tested material after SE have been studied. The experimental results show that the equal-axial ultrafine microstructures can be introduced to the bulk test material during sandglass extrusion. The high strain rate superplasticity can be realized.
