The orientation effect of θʹ precipitates in stress-aged Al-Cu alloys has ambiguous interpretations. One view is that θʹ precipitates prefer to grow on the habit planes perpendicular to the applied compressive stres...The orientation effect of θʹ precipitates in stress-aged Al-Cu alloys has ambiguous interpretations. One view is that θʹ precipitates prefer to grow on the habit planes perpendicular to the applied compressive stress, while the other view suggests growth on habit planes parallel to the applied stress. In this study, stress-aged Al-4 wt.%Cu single crystal was sampled from three different <100>Al zone axes to observe the distribution of θʹ precipitates. A hybrid Monte-Carlo/ molecular dynamics simulations were used to investigate the orientation effect of θʹ precipitates. The simulation results are consistent with experimental observations and indicate that θʹ precipitates prefer to grow on the habit planes that are parallel to the direction of the applied compressive stress, not along the planes perpendicular to it. It is also found that 1/2<110> perfect dislocations are generated as θʹ precipitates plates grow thicker, and the reaction of 1/2<110> perfect dislocations decomposing into 1/6<112> Shockley dislocations lead to an increase in the length of θʹ precipitates. The former does not enhance the orientation effect, whereas the latter leads to a more significant orientation effect. Additionally, the degree of the orientation effect of θʹ precipitates is determined by the reduction of 1/2<110> dislocations with a positive correlation between them.展开更多
The constitutive relationships of Al-Mg-Si alloy deformed at various strain rates,temperatures and strains were studied.The microstructure evolution was quantitatively characterized and analyzed,including recrystalliz...The constitutive relationships of Al-Mg-Si alloy deformed at various strain rates,temperatures and strains were studied.The microstructure evolution was quantitatively characterized and analyzed,including recrystallization fraction,grain sizes,local misorientation,geometrically necessary dislocation and stored strain energy during hot deformation and subsequent heat treatment.The results show that the dislocation density and energy storage are linear with ln Z during hot deformation and subsequent heat treatment,indicating continuous recrystallization occurring in both processes.With higher ln Z,the dislocation density declines more sharply during subsequent heat treatment.When ln Z is less than 28,dislocation density becomes more stable with less reduction during subsequent heat treatment after hot deformation.As these dislocations distribute along low angle grain boundaries,the subgrain has good stability during subsequent heat treatment.The main recrystallization mechanism during hot deformation is continuous dynamic recrystallization,accompanied by geometric dynamic recrystallization at higher ln Z.展开更多
基金Project(2023YFB3710503) supported by the National Key R&D Program of ChinaProject(52305439) supported by the National Natural Science Foundation of China。
文摘The orientation effect of θʹ precipitates in stress-aged Al-Cu alloys has ambiguous interpretations. One view is that θʹ precipitates prefer to grow on the habit planes perpendicular to the applied compressive stress, while the other view suggests growth on habit planes parallel to the applied stress. In this study, stress-aged Al-4 wt.%Cu single crystal was sampled from three different <100>Al zone axes to observe the distribution of θʹ precipitates. A hybrid Monte-Carlo/ molecular dynamics simulations were used to investigate the orientation effect of θʹ precipitates. The simulation results are consistent with experimental observations and indicate that θʹ precipitates prefer to grow on the habit planes that are parallel to the direction of the applied compressive stress, not along the planes perpendicular to it. It is also found that 1/2<110> perfect dislocations are generated as θʹ precipitates plates grow thicker, and the reaction of 1/2<110> perfect dislocations decomposing into 1/6<112> Shockley dislocations lead to an increase in the length of θʹ precipitates. The former does not enhance the orientation effect, whereas the latter leads to a more significant orientation effect. Additionally, the degree of the orientation effect of θʹ precipitates is determined by the reduction of 1/2<110> dislocations with a positive correlation between them.
基金Project(2016YFB0300901)supported by the National Key R&D Program of ChinaProject(TC190H3ZV/2)supported by the National Building Project of Application Demonstration Platform on New Materials Products,ChinaProject(15308469779)supported by Key Laboratory of National Science and Technology for Equipment Pre-research,China。
文摘The constitutive relationships of Al-Mg-Si alloy deformed at various strain rates,temperatures and strains were studied.The microstructure evolution was quantitatively characterized and analyzed,including recrystallization fraction,grain sizes,local misorientation,geometrically necessary dislocation and stored strain energy during hot deformation and subsequent heat treatment.The results show that the dislocation density and energy storage are linear with ln Z during hot deformation and subsequent heat treatment,indicating continuous recrystallization occurring in both processes.With higher ln Z,the dislocation density declines more sharply during subsequent heat treatment.When ln Z is less than 28,dislocation density becomes more stable with less reduction during subsequent heat treatment after hot deformation.As these dislocations distribute along low angle grain boundaries,the subgrain has good stability during subsequent heat treatment.The main recrystallization mechanism during hot deformation is continuous dynamic recrystallization,accompanied by geometric dynamic recrystallization at higher ln Z.
