The evolution of hardness and microstructures of 1050 aluminum alloy prepared by hot rolling and subsequent equal- channel angular pressing at cryogenic temperature (cryoECAP) after annealing at 150?400 °C for 1 ...The evolution of hardness and microstructures of 1050 aluminum alloy prepared by hot rolling and subsequent equal- channel angular pressing at cryogenic temperature (cryoECAP) after annealing at 150?400 °C for 1 h without and with magnetic field of 12 T was investigated. The electron back scattering diffraction pattern (EBSD) and transmission electron microscopy (TEM) were utilized to characterize the grain microstructures and dislocations. It is demonstrated that the hot rolling before cryoECAP produces more equiaxed grains with a smaller average size and a higher fraction of high angle boundaries (HABs) in the subsequent cryoECAPed 1050 aluminum alloy, thus accelerating the recovery and recrystallization of cryoECAPed alloy and produces more homogeneous microstructure during annealing. The magnetic field promotes the recovery and recrystallization and leads to much lower hardness at 150?250 °C, while it can suppress the abnormal grain growth and form more homogeneous grain size distributions annealed at 300?400 °C.展开更多
The effect of rolling to a total effective strain of 2 at the liquid nitrogen temperature and subsequent natural and artificial aging on the structure and service properties of the pre-quenched hot-pressed 2024 alumin...The effect of rolling to a total effective strain of 2 at the liquid nitrogen temperature and subsequent natural and artificial aging on the structure and service properties of the pre-quenched hot-pressed 2024 aluminum alloy was investigated.Using optical and electron microscopy,and X-ray analysis,it was found that the cryorolling did not qualitatively change the type of the initial coarse-fibered microstructure,but produced a well-developed nanocell substructure inside fibers.Further aging led to decomposition of the preliminary supersaturated and work-hardened aluminum solid solution and precipitation of strengthening phases in the statically recovered and/or recrystallized matrix.As a result,the rolled and naturally aged alloy demonstrated the yield and ultimate tensile strengths(YS=590 MPa,UTS=640 MPа)much higher than those in the pressed andТ6-heat treated alloy at equal elongation to failure(El^6%).Artificial aging at a temperature less than conventional T6 route could provide the extra alloy strengthening and the unique balance of mechanical properties,involving enhanced strength(YS=610 MPa,UTS=665 MPа)and ductility(El^10%),and good static crack resistance(the specific works for crack formation and growth were 42 and 18 k J/m^2,respectively)and corrosion resistance(the intensity and depth of intercrystalline corrosion were 23%and 50μm,respectively).展开更多
The objective of the investigation is to evaluate the influence of the Zener-Hollomon parameter on substructure and texture evolution in iron-containing wrought aluminium alloys (type AA8011). Methods applied are X-ra...The objective of the investigation is to evaluate the influence of the Zener-Hollomon parameter on substructure and texture evolution in iron-containing wrought aluminium alloys (type AA8011). Methods applied are X-ray texture analysis, electron backscatter diffraction (EBSD) and optical microscopy. The results show a serious impact of the Zener-Hollomon parameter on cube texture evolution during the thermomechanical treatment in iron-containing aluminium alloys. An increase in the Zener-Hollomon parameter reduces the survivability of cube texture during hot deformation and reinforces particle-stimulated nucleation (PSN) during the annealing process. However, thermomechanical treatment at low temperatures leads to active precipitation and as a result fine-dispersed participles tend to block all nuclei except for those producing large cube-oriented grains. It is concluded that in iron-containing wrought aluminium alloys, the general correlation between the Zener-Hollomon parameter and subgrain size is similar to that observed in 3xxx series alloys and can be described by the specific set of equations derived.展开更多
Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in...Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in Al 1100 alloy has been studied in detail.Before subjecting to 50%cryorolling,samples were pre-annealed at 250℃ for 2 h and pre-solution treated at 540℃ for 1 h.X-ray diffraction and HRTEM techniques were used to understand the crystallite size,lattice strain and dislocation configuration in the processed alloy.The results indicate that the pre-annealed sample has the highest grain aspect ratio(4.43),the smallest crystallite size(37.53 nm),the highest lattice strain(9.12×10^(−3))and the highest dislocation density(45.16×10^(13) m^(−2))among the tested sample.The pre-annealed sample shows a significant improvement of 43.44%,24.64%and 20.33%in hardness,ultimate tensile strength and yield strength.Both pre-annealed and pre-solution treated samples show improved corrosion resistance when compared to cryorolled samples without any pre-treatment,with the pre-annealed sample showing the best corrosion resistance.展开更多
基金Project(2011CB606403)supported by the State Basic Research Development Program of ChinaProjects(51171044,51174058)supported by the National Natural Science Foundation of ChinaProject(2012CB723307)supported by the State Basic Research Development Program of China
文摘The evolution of hardness and microstructures of 1050 aluminum alloy prepared by hot rolling and subsequent equal- channel angular pressing at cryogenic temperature (cryoECAP) after annealing at 150?400 °C for 1 h without and with magnetic field of 12 T was investigated. The electron back scattering diffraction pattern (EBSD) and transmission electron microscopy (TEM) were utilized to characterize the grain microstructures and dislocations. It is demonstrated that the hot rolling before cryoECAP produces more equiaxed grains with a smaller average size and a higher fraction of high angle boundaries (HABs) in the subsequent cryoECAPed 1050 aluminum alloy, thus accelerating the recovery and recrystallization of cryoECAPed alloy and produces more homogeneous microstructure during annealing. The magnetic field promotes the recovery and recrystallization and leads to much lower hardness at 150?250 °C, while it can suppress the abnormal grain growth and form more homogeneous grain size distributions annealed at 300?400 °C.
文摘The effect of rolling to a total effective strain of 2 at the liquid nitrogen temperature and subsequent natural and artificial aging on the structure and service properties of the pre-quenched hot-pressed 2024 aluminum alloy was investigated.Using optical and electron microscopy,and X-ray analysis,it was found that the cryorolling did not qualitatively change the type of the initial coarse-fibered microstructure,but produced a well-developed nanocell substructure inside fibers.Further aging led to decomposition of the preliminary supersaturated and work-hardened aluminum solid solution and precipitation of strengthening phases in the statically recovered and/or recrystallized matrix.As a result,the rolled and naturally aged alloy demonstrated the yield and ultimate tensile strengths(YS=590 MPa,UTS=640 MPа)much higher than those in the pressed andТ6-heat treated alloy at equal elongation to failure(El^6%).Artificial aging at a temperature less than conventional T6 route could provide the extra alloy strengthening and the unique balance of mechanical properties,involving enhanced strength(YS=610 MPa,UTS=665 MPа)and ductility(El^10%),and good static crack resistance(the specific works for crack formation and growth were 42 and 18 k J/m^2,respectively)and corrosion resistance(the intensity and depth of intercrystalline corrosion were 23%and 50μm,respectively).
基金funded by a grant of the Russian Science Foundation (Project 18-79-10099)
文摘The objective of the investigation is to evaluate the influence of the Zener-Hollomon parameter on substructure and texture evolution in iron-containing wrought aluminium alloys (type AA8011). Methods applied are X-ray texture analysis, electron backscatter diffraction (EBSD) and optical microscopy. The results show a serious impact of the Zener-Hollomon parameter on cube texture evolution during the thermomechanical treatment in iron-containing aluminium alloys. An increase in the Zener-Hollomon parameter reduces the survivability of cube texture during hot deformation and reinforces particle-stimulated nucleation (PSN) during the annealing process. However, thermomechanical treatment at low temperatures leads to active precipitation and as a result fine-dispersed participles tend to block all nuclei except for those producing large cube-oriented grains. It is concluded that in iron-containing wrought aluminium alloys, the general correlation between the Zener-Hollomon parameter and subgrain size is similar to that observed in 3xxx series alloys and can be described by the specific set of equations derived.
基金Universiti Sains Malaysia for providing the fund for this study under RU grant No.1001/PBahan/8014105.
文摘Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in Al 1100 alloy has been studied in detail.Before subjecting to 50%cryorolling,samples were pre-annealed at 250℃ for 2 h and pre-solution treated at 540℃ for 1 h.X-ray diffraction and HRTEM techniques were used to understand the crystallite size,lattice strain and dislocation configuration in the processed alloy.The results indicate that the pre-annealed sample has the highest grain aspect ratio(4.43),the smallest crystallite size(37.53 nm),the highest lattice strain(9.12×10^(−3))and the highest dislocation density(45.16×10^(13) m^(−2))among the tested sample.The pre-annealed sample shows a significant improvement of 43.44%,24.64%and 20.33%in hardness,ultimate tensile strength and yield strength.Both pre-annealed and pre-solution treated samples show improved corrosion resistance when compared to cryorolled samples without any pre-treatment,with the pre-annealed sample showing the best corrosion resistance.
