In order to study the welding process,microstructure and properties of Al-Mg-Mn-Sc-Zr alloy,comparative methods of friction stir welding（FSW） and tungsten inert gas（TIG） were applied to the two conditions of this ...In order to study the welding process,microstructure and properties of Al-Mg-Mn-Sc-Zr alloy,comparative methods of friction stir welding（FSW） and tungsten inert gas（TIG） were applied to the two conditions of this alloy,namely hot rolled plate and cold rolled-annealed plate.The relationships between microstructures and properties of the welded joints were investigated by means of optical microscopy and transmission electron microscopy.Compared with the base metal,the strength of FSW and TIG welded joints decreased,and the FSW welding coefficients were higher than the TIG welding coefficients.The loss of substructure strengthening and a very little loss of precipitation strengthening of Al3（Sc,Zr） cause the decreased strength of FSW welded joint.But for the TIG welded joint,the disappearance of both the strain hardening and most precipitation strengthening effect of Al3（Sc,Zr） particles contributed to its softening.At the same time,the grains in weld nugget zone of FSW welded joints were finer than those in the molten zone of TIG welded joints.展开更多
In order to evaluate the degree and severity of Al-Mg-Mn-Sc-Zr alloy in exfoliation corrosion(EXCO) solution quickly and nondestructively, electrochemical impedance spectroscopy(EIS) technique was employed. The Al-Mg-...In order to evaluate the degree and severity of Al-Mg-Mn-Sc-Zr alloy in exfoliation corrosion(EXCO) solution quickly and nondestructively, electrochemical impedance spectroscopy(EIS) technique was employed. The Al-Mg-Mn-Sc-Zr alloy suffers pitting corrosion in the EXCO solution. During pit incubation, the Nyquist diagram is composed of a depressed capacitive arc at high-mediate frequency and an inductive arc at low frequency. The inductive arc fades with immersion time, and the beginning of pitting corrosion and the appearance of two capacitive arcs have simultaneity. During pit propagation, the Nyquist diagram is composed of two overlapped capacitive arcs. As time goes on, two time constants are more clearly distinguished. The high frequency and low frequency capacitive arc are aroused by passive surface and new interface, respectively. An equivalent circuit is designed to fit EIS, and the experimental results and the fitted results have good correspondence. The degree and severity of pitting corrosion can be obtained by the features of EIS and comparing the fitted values of parameters at different times.展开更多
The effect of homogenization on the hardness,tensile properties,electrical conductivity and microstructure of as-cast Al-6Mg-0.4Mn-0.25Sc-0.12Zr alloy was studied.The results show that during homogenization as-cast st...The effect of homogenization on the hardness,tensile properties,electrical conductivity and microstructure of as-cast Al-6Mg-0.4Mn-0.25Sc-0.12Zr alloy was studied.The results show that during homogenization as-cast studied alloy has obviously hardening effect that is similar to aging hardening behavior in traditional Al alloys.The precipitates are mainly Al3(Sc,Zr)and Al6Mn.When homogenization temperature increases the hardness peak value is declined and the time corresponding to hardness peak value is shortened.The electrical conductivity of the alloy monotonously increases with increasing homogenization temperature and time.The decomposition of the supersaturated solid solution containing Sc and Zr which is formed during direct chilling casting and the precipitation of Al3(Sc,Zr)cause hardness increasing.The depletion of the matrix solid solubility decreases the ability of electron scattering in the alloy,resulting in the electrical conductivity increased.Tensile property result at hot rolling state shows that the optimal homogenization treatment processing is holding at 300-350 ℃ for 6-8 h.展开更多
Al-5.8Mg-0.4Mn-0.25Sc-0.1Zr （mass fraction, %） alloys were prepared by water chilling copper mould ingot metallurgy processing which was protected by active flux. The recrystallization temperature and nucleation mec...Al-5.8Mg-0.4Mn-0.25Sc-0.1Zr （mass fraction, %） alloys were prepared by water chilling copper mould ingot metallurgy processing which was protected by active flux. The recrystallization temperature and nucleation mechanism of the alloy were studied by means of hardness tests, observations of optical microscopy and transmission electron microscopy. The results show that the anti-crystallization ability can be significantly improved by adding minor Sc and Zr into Al-Mg-Mn alloy. This can be proved by a much higher recrystalliztion temperature （450 ~C） than Al-Mg-Mn alloy without Sc and Zr （150 ℃）. The main reason of the great increase of recrystallization temperature can be attributed to the strong pinning effect of highly disperseded Al3（Sc,Zr） particles on dislocations and sub-grain boundaries. The recrystallizing process reveals itself the nucleation mechanism of the alloy involving not only the sub-grain coalescence but also the sub-grain growth.展开更多
To quest for the best combination of mechanical properties and exfoliation corrosion resisting property of Al-Mg-Mn base alloys, and to seek after the effect of Sc and Zr on mechanical and exfoliation corrosion proper...To quest for the best combination of mechanical properties and exfoliation corrosion resisting property of Al-Mg-Mn base alloys, and to seek after the effect of Sc and Zr on mechanical and exfoliation corrosion properties of Al-Mg-Mn alloys, comparative research technique was used, the mechanical properties of Al-Mg-Mn alloys with and without minor Sc and Zr treated by different annealing were measured, the degrees of exfoliation corrosion for these alloys through accelerated exfoliation corrosion test were evaluated, and polarization curves of these alloys were measured, too. The micro-morphologies of corrosion specimens were observed by SEM and the corrosion product was analyzed using EDS. Optical microscope and TEM were used, the relationship between their microstruc-tures and mechanical properties, exfoliation corrosion resisting property was investigated, and the results show that the addition of minor Sc and Zr can enhance the strength greatly and also improve the combination of strength and plasticity. Moreover, the addition of minor Sc, Zr does not cause appreciable decrease of exfoliation corrosion resisting property, the Al-Mg-Mn-Sc-Zr alloy annealed at 350 ℃ for 1 h has excellent combination of mechanical properties and exfoliation corrosion resisting property, the satisfied combination of mechanical properties nad exfoliation corrosion resisting property can be obtained by means of adding minor Sc and Zr, decreasing the content of Mn, and adopting reasonable annealing practice.展开更多
The effect of Sc and Zr on the superplastic properties of Al-Mg-Mn alloy sheets was investigated by control experiment. The superplastic properties and the mechanism of superplastic deformation of the two alloys were ...The effect of Sc and Zr on the superplastic properties of Al-Mg-Mn alloy sheets was investigated by control experiment. The superplastic properties and the mechanism of superplastic deformation of the two alloys were studied by means of optical microscope, scanning electronic microscope and transmission electron microscope. The elongation to failure of Al-Mg-Mn-Sc-Zr alloy is larger than that of Al-Mg-Mn alloy at the same temperature and initial strain rate. The variation of strain rate sensitivity index is similar to that of elongation to failure. In addition, Al-Mg-Mn-Sc-Zr alloy exhibits higher strain rate superplastic property. The activation energies of the two alloys that are calculated by constitutive equation and linear regression method approach the energy of grain boundary diffusion. The addition of Sc and Zr decreases activation energy and improves the superplastic property of Al-Mg-Mn alloy. The addition of Sc and Zr refines the grain structure greatly. The main mechanism of superplastic deformation of the two alloys is grain boundary sliding accommodated by grain boundary diffusion. The fine grain structure and high density of grain boundary, benefit grain boundary sliding, and dynamic recrystallization brings new fine grain and high angle grain boundary which benefit grain boundary sliding too. Grain boundary diffusion, dislocation motion and dynamic recrystallization harmonize the grain boundary sliding during deformation.展开更多
基金Project (MKPT-2005-16ZD) supported by the National Key Scientific and Technological Project of ChinaProject supported by the Postdoctoral Science Foundation of Central South University,China
文摘In order to study the welding process,microstructure and properties of Al-Mg-Mn-Sc-Zr alloy,comparative methods of friction stir welding（FSW） and tungsten inert gas（TIG） were applied to the two conditions of this alloy,namely hot rolled plate and cold rolled-annealed plate.The relationships between microstructures and properties of the welded joints were investigated by means of optical microscopy and transmission electron microscopy.Compared with the base metal,the strength of FSW and TIG welded joints decreased,and the FSW welding coefficients were higher than the TIG welding coefficients.The loss of substructure strengthening and a very little loss of precipitation strengthening of Al3（Sc,Zr） cause the decreased strength of FSW welded joint.But for the TIG welded joint,the disappearance of both the strain hardening and most precipitation strengthening effect of Al3（Sc,Zr） particles contributed to its softening.At the same time,the grains in weld nugget zone of FSW welded joints were finer than those in the molten zone of TIG welded joints.
文摘In order to evaluate the degree and severity of Al-Mg-Mn-Sc-Zr alloy in exfoliation corrosion(EXCO) solution quickly and nondestructively, electrochemical impedance spectroscopy(EIS) technique was employed. The Al-Mg-Mn-Sc-Zr alloy suffers pitting corrosion in the EXCO solution. During pit incubation, the Nyquist diagram is composed of a depressed capacitive arc at high-mediate frequency and an inductive arc at low frequency. The inductive arc fades with immersion time, and the beginning of pitting corrosion and the appearance of two capacitive arcs have simultaneity. During pit propagation, the Nyquist diagram is composed of two overlapped capacitive arcs. As time goes on, two time constants are more clearly distinguished. The high frequency and low frequency capacitive arc are aroused by passive surface and new interface, respectively. An equivalent circuit is designed to fit EIS, and the experimental results and the fitted results have good correspondence. The degree and severity of pitting corrosion can be obtained by the features of EIS and comparing the fitted values of parameters at different times.
基金Project(2005CB623705-01) supported by the National Key Fundamental Research and Development Program of ChinaProject(MKPT-2004-16ZD) supported by the National 10th Five-Year Plan Program
文摘The effect of homogenization on the hardness,tensile properties,electrical conductivity and microstructure of as-cast Al-6Mg-0.4Mn-0.25Sc-0.12Zr alloy was studied.The results show that during homogenization as-cast studied alloy has obviously hardening effect that is similar to aging hardening behavior in traditional Al alloys.The precipitates are mainly Al3(Sc,Zr)and Al6Mn.When homogenization temperature increases the hardness peak value is declined and the time corresponding to hardness peak value is shortened.The electrical conductivity of the alloy monotonously increases with increasing homogenization temperature and time.The decomposition of the supersaturated solid solution containing Sc and Zr which is formed during direct chilling casting and the precipitation of Al3(Sc,Zr)cause hardness increasing.The depletion of the matrix solid solubility decreases the ability of electron scattering in the alloy,resulting in the electrical conductivity increased.Tensile property result at hot rolling state shows that the optimal homogenization treatment processing is holding at 300-350 ℃ for 6-8 h.
基金National Natural Science Foundation of China(Nos.52001140,52274363)Guangdong Basic Applied Basic Research Foundation,China(Nos.2022A1515010558,2022A1515011597,2022A1515240065)。
基金Project(2012CB619503)supported by the National Basic Research Program of China
文摘Al-5.8Mg-0.4Mn-0.25Sc-0.1Zr （mass fraction, %） alloys were prepared by water chilling copper mould ingot metallurgy processing which was protected by active flux. The recrystallization temperature and nucleation mechanism of the alloy were studied by means of hardness tests, observations of optical microscopy and transmission electron microscopy. The results show that the anti-crystallization ability can be significantly improved by adding minor Sc and Zr into Al-Mg-Mn alloy. This can be proved by a much higher recrystalliztion temperature （450 ~C） than Al-Mg-Mn alloy without Sc and Zr （150 ℃）. The main reason of the great increase of recrystallization temperature can be attributed to the strong pinning effect of highly disperseded Al3（Sc,Zr） particles on dislocations and sub-grain boundaries. The recrystallizing process reveals itself the nucleation mechanism of the alloy involving not only the sub-grain coalescence but also the sub-grain growth.
文摘To quest for the best combination of mechanical properties and exfoliation corrosion resisting property of Al-Mg-Mn base alloys, and to seek after the effect of Sc and Zr on mechanical and exfoliation corrosion properties of Al-Mg-Mn alloys, comparative research technique was used, the mechanical properties of Al-Mg-Mn alloys with and without minor Sc and Zr treated by different annealing were measured, the degrees of exfoliation corrosion for these alloys through accelerated exfoliation corrosion test were evaluated, and polarization curves of these alloys were measured, too. The micro-morphologies of corrosion specimens were observed by SEM and the corrosion product was analyzed using EDS. Optical microscope and TEM were used, the relationship between their microstruc-tures and mechanical properties, exfoliation corrosion resisting property was investigated, and the results show that the addition of minor Sc and Zr can enhance the strength greatly and also improve the combination of strength and plasticity. Moreover, the addition of minor Sc, Zr does not cause appreciable decrease of exfoliation corrosion resisting property, the Al-Mg-Mn-Sc-Zr alloy annealed at 350 ℃ for 1 h has excellent combination of mechanical properties and exfoliation corrosion resisting property, the satisfied combination of mechanical properties nad exfoliation corrosion resisting property can be obtained by means of adding minor Sc and Zr, decreasing the content of Mn, and adopting reasonable annealing practice.
基金Project(2005CB623705) supported by the National Basic Research Program of China
文摘The effect of Sc and Zr on the superplastic properties of Al-Mg-Mn alloy sheets was investigated by control experiment. The superplastic properties and the mechanism of superplastic deformation of the two alloys were studied by means of optical microscope, scanning electronic microscope and transmission electron microscope. The elongation to failure of Al-Mg-Mn-Sc-Zr alloy is larger than that of Al-Mg-Mn alloy at the same temperature and initial strain rate. The variation of strain rate sensitivity index is similar to that of elongation to failure. In addition, Al-Mg-Mn-Sc-Zr alloy exhibits higher strain rate superplastic property. The activation energies of the two alloys that are calculated by constitutive equation and linear regression method approach the energy of grain boundary diffusion. The addition of Sc and Zr decreases activation energy and improves the superplastic property of Al-Mg-Mn alloy. The addition of Sc and Zr refines the grain structure greatly. The main mechanism of superplastic deformation of the two alloys is grain boundary sliding accommodated by grain boundary diffusion. The fine grain structure and high density of grain boundary, benefit grain boundary sliding, and dynamic recrystallization brings new fine grain and high angle grain boundary which benefit grain boundary sliding too. Grain boundary diffusion, dislocation motion and dynamic recrystallization harmonize the grain boundary sliding during deformation.
基金Science and Technology Plan Project of Inner Mongolia(201802029)Major Science and Technology Projects of Inner Mongolia Autonomous Region(zdzx2018031)Graduate Research Innovation Project of Inner Mongolia Autonomous Region(S20210180Z)。
