The effects of Ce and Ti additions on the microstructures and mechanical properties of an Al-Cu-Mg-Ag alloy have been studied, It has been shown that either Ce or Ti can decrease the as-cast grain size of the Al-Cu-Mg...The effects of Ce and Ti additions on the microstructures and mechanical properties of an Al-Cu-Mg-Ag alloy have been studied, It has been shown that either Ce or Ti can decrease the as-cast grain size of the Al-Cu-Mg-Ag alloy, increase the nucleation ratio for Ω phase as heterogeneous nucleation centers, inhibit the growth of Ω phase during aging, and thus increase the volume fraction and decrease the spacing of Ω phase. These microstructures increase the yield strength and tensile strength. However, if both Ce and Ti are added to the alloy, they form （Ce,Ti）-contained compounds and increase the grain size during casting, but have no effects on the nucleation and the growth of Ω phase during aging. The alloy containing both Ce and Ti has a relatively lower Vicks hardness and strength compared to the alloy containing either Ce or Ti.展开更多
The effect of stress aging on the nucleation and growth of precipitates in Al-3 .88%Cu and Al-3.87%Cu-0.56%Mg-0.56%Ag alloys was investigated by electric res istivity measurement and transmission electron microscopy o...The effect of stress aging on the nucleation and growth of precipitates in Al-3 .88%Cu and Al-3.87%Cu-0.56%Mg-0.56%Ag alloys was investigated by electric res istivity measurement and transmission electron microscopy observation. The resul ts indicate that external stress promotes the formation of clusters of solute at oms or GP zones,but retards the growth of θ′ and Ω phases. A critica l phenomenon that the microstructural evolution will be modified at a certain ex ternal extress value is found in Al-Cu-Mg-Ag alloy. The applied external stre ss during aging induces preferentially oriented precipitations of θ′ and Ω in Al-Cu and Al-Cu-Mg-Ag alloys,respectively. The origin of stress- induced orientation effect is understood by analyzing interaction between extern al stress and misfit strain by Eshelby elastic inclusion theory.展开更多
The aging behavior of Al-Cu-Mg-Ag alloys with high Cu/Mg was studied by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) using synchrotron radiation. TEM study reveals that the major stre...The aging behavior of Al-Cu-Mg-Ag alloys with high Cu/Mg was studied by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) using synchrotron radiation. TEM study reveals that the major strengthening phases of the alloy after aging at 160?C for 10 h are Ω and less θ′. SAXS study shows that the scattering patterns are composed of several concentric circles at the beginning of aging process, which is replaced by the butterfly-wings scattering patterns with the increase of aging time. The butterfly-wings scattering patterns are composed of several branches. The angles between the branches are roughly equal to that between the habit planes of precipitates. The evolution of Guinier radius with aging time indicates the good coarsening resistance of the precipitates. The evolution of integrated intensity is consistent with the classical two-step precipitation process.展开更多
High cyclic fatigue(HCF)behavior of an AA2139alloy belonging to Al-Cu-Mg-Ag system in T6and T840conditionswas examined.The T840treatment involving cold rolling with a40%reduction prior to peak ageing provides an incre...High cyclic fatigue(HCF)behavior of an AA2139alloy belonging to Al-Cu-Mg-Ag system in T6and T840conditionswas examined.The T840treatment involving cold rolling with a40%reduction prior to peak ageing provides an increase in tensilestrength compared with the T6condition.However,fatigue lifetime for two material conditions was nearly the same since there isweak effect of thermomechanical processing on micro-mechanisms of crack initiation and growth.展开更多
The hot deformation behavior of Al-Cu-Mg-Ag was studied by isothermal hot compression tests in the temperature range of 573-773 K and strain rate range of 0.001-1 s^-1 on a Gleeble 1500 D thermal mechanical simulator....The hot deformation behavior of Al-Cu-Mg-Ag was studied by isothermal hot compression tests in the temperature range of 573-773 K and strain rate range of 0.001-1 s^-1 on a Gleeble 1500 D thermal mechanical simulator. The results show the flow stress of Al-Cu-Mg-Ag alloy increases with strain rate and decreases after a peak value, indicating dynamic recovery and recrystallization. A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate and temperature, the flow stress equation is estimated to illustrate the relation of strain rate and stress and temperature during high temperature deformation process. The processing maps exhibit two domains as optimum fields for hot deformation at different strains, including the high strain rate domain in 623-773 K and the low strain rate domain in 573-673 K.展开更多
基金This study was financially supported by the State Key Fundamental Research Project on Al, China (No. 2005CB623704).
文摘The effects of Ce and Ti additions on the microstructures and mechanical properties of an Al-Cu-Mg-Ag alloy have been studied, It has been shown that either Ce or Ti can decrease the as-cast grain size of the Al-Cu-Mg-Ag alloy, increase the nucleation ratio for Ω phase as heterogeneous nucleation centers, inhibit the growth of Ω phase during aging, and thus increase the volume fraction and decrease the spacing of Ω phase. These microstructures increase the yield strength and tensile strength. However, if both Ce and Ti are added to the alloy, they form （Ce,Ti）-contained compounds and increase the grain size during casting, but have no effects on the nucleation and the growth of Ω phase during aging. The alloy containing both Ce and Ti has a relatively lower Vicks hardness and strength compared to the alloy containing either Ce or Ti.
文摘The effect of stress aging on the nucleation and growth of precipitates in Al-3 .88%Cu and Al-3.87%Cu-0.56%Mg-0.56%Ag alloys was investigated by electric res istivity measurement and transmission electron microscopy observation. The resul ts indicate that external stress promotes the formation of clusters of solute at oms or GP zones,but retards the growth of θ′ and Ω phases. A critica l phenomenon that the microstructural evolution will be modified at a certain ex ternal extress value is found in Al-Cu-Mg-Ag alloy. The applied external stre ss during aging induces preferentially oriented precipitations of θ′ and Ω in Al-Cu and Al-Cu-Mg-Ag alloys,respectively. The origin of stress- induced orientation effect is understood by analyzing interaction between extern al stress and misfit strain by Eshelby elastic inclusion theory.
基金financially supported by the National Natural Science Foundation of China(No.51004018)
文摘The aging behavior of Al-Cu-Mg-Ag alloys with high Cu/Mg was studied by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) using synchrotron radiation. TEM study reveals that the major strengthening phases of the alloy after aging at 160?C for 10 h are Ω and less θ′. SAXS study shows that the scattering patterns are composed of several concentric circles at the beginning of aging process, which is replaced by the butterfly-wings scattering patterns with the increase of aging time. The butterfly-wings scattering patterns are composed of several branches. The angles between the branches are roughly equal to that between the habit planes of precipitates. The evolution of Guinier radius with aging time indicates the good coarsening resistance of the precipitates. The evolution of integrated intensity is consistent with the classical two-step precipitation process.
基金a joint project between USATU (Ufa State Aviation Technical University) and UMPO (Ufa Engine Industrial Association), which is entitled “Elaboration and industrial development of high-precision shaping coordinated technologies and superficial hardening of responsible details from Al-alloys with heightened constructional energy efficiency”. This project was implemented under contract No. 40/10-30976/NCh-NCh01-13-KhGthe Ministry of Education and Science of the Russian Federation (contract No.02.G25.31.0010 between UMPO and the Ministry of Education and Science of the Russian Federation) via the Resolution of the Russian Federation Government No.218 from April 9,2010
文摘High cyclic fatigue(HCF)behavior of an AA2139alloy belonging to Al-Cu-Mg-Ag system in T6and T840conditionswas examined.The T840treatment involving cold rolling with a40%reduction prior to peak ageing provides an increase in tensilestrength compared with the T6condition.However,fatigue lifetime for two material conditions was nearly the same since there isweak effect of thermomechanical processing on micro-mechanisms of crack initiation and growth.
基金the National Basic Research Program of China(No.2005CB623705)
文摘The hot deformation behavior of Al-Cu-Mg-Ag was studied by isothermal hot compression tests in the temperature range of 573-773 K and strain rate range of 0.001-1 s^-1 on a Gleeble 1500 D thermal mechanical simulator. The results show the flow stress of Al-Cu-Mg-Ag alloy increases with strain rate and decreases after a peak value, indicating dynamic recovery and recrystallization. A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate and temperature, the flow stress equation is estimated to illustrate the relation of strain rate and stress and temperature during high temperature deformation process. The processing maps exhibit two domains as optimum fields for hot deformation at different strains, including the high strain rate domain in 623-773 K and the low strain rate domain in 573-673 K.
