To get a full understanding of hot extrusion,solid solution treatment and aging process on the Al−0.56Mg−0.63Si alloy,the microstructure and mechanical properties of a U-shaped profile were studied through optical mic...To get a full understanding of hot extrusion,solid solution treatment and aging process on the Al−0.56Mg−0.63Si alloy,the microstructure and mechanical properties of a U-shaped profile were studied through optical microscopy,scanning electrical microscopy,transmission electrical microscopy,hardness,and tensile tests.The coarse equiaxed grains existed near the profile edge as a result of the dynamic recrystallization nucleation and exceeding growth during hot extrusion.The fibrous deformed and sub-structured grains located between the two coarse grain layers,due to the occurrence of work-hardening and dynamic recovery.Perpendicular needle β′′precipitates were distributed inside the grain,and obvious precipitates-free zone appeared after aging treatment.The tensile strength,yield strength and elongation of the aged Al−Mg−Si alloy U-shaped profile were no less than 279.4 MPa,258.6 MPa,and 21.6%,respectively.The fracture morphology showed dimple rupture characteristics.The precipitates and grain boundaries played key role in the strengthening contribution.展开更多
This paper reports that the transmission of O6＋ ions with energy of 150keV through capillaries in an uncoated Al2O3 membrane was measured, and agreements with previously reported results in general angular distributi...This paper reports that the transmission of O6＋ ions with energy of 150keV through capillaries in an uncoated Al2O3 membrane was measured, and agreements with previously reported results in general angular distribution of the transmitted ions and the transmission fractions as a function of the tilt angle well fitted to Gaussian-like functions were observed. Due tousing an uncoated capillary membrane, our φc is larger than that using a gold-coated one with a smaller value of Ep/q, which suggests a larger equilibrium charge Q∞ in our experiment. The observed special width variation with time and a larger width than that using a smaller Ep/q were qualitatively explained by using mean-field classical transport theory based on a classical-trajectory Monte Carlo simulation.展开更多
The dendrite growth process during the solidification of the Al-4.5%Cu binary alloy was simulated using the phase-field model, proposed by Kim et al. Solute diffusion equation and heat transfer equation were solved si...The dendrite growth process during the solidification of the Al-4.5%Cu binary alloy was simulated using the phase-field model, proposed by Kim et al. Solute diffusion equation and heat transfer equation were solved simultaneously. The effects of the noise on the dendrite growth, solute and temperature profile in the undercooled alloy melt were investigated. The results indicate that the noise can trigger the growth of the secondary arms, and increase the highest temperature and solute concentration, but not influence the tip operating state. The solute and temperature gradients in the tip are the highest.展开更多
The latest applications of laser shock processing were summarized in this paper,and laser peening with water confined layer has been applied to Ti6Al4V titanium alloy using Nd:glass pulse laser.The profile of plastic ...The latest applications of laser shock processing were summarized in this paper,and laser peening with water confined layer has been applied to Ti6Al4V titanium alloy using Nd:glass pulse laser.The profile of plastic deformation and residual stresses on metal surface were studied with different laser power density.The investigation results show that peak depth of plastic deformation is in linear proportion to laser power density (5.75GW/cm2 to 9.5 GW/cm2),and maximal surface compressive residual stress is up to 375MPa at 8.25GW/cm2.It was ensured that the compressive residual stress field related to laser power density and shocked times.As spot overlapping ratio of 33%,the circle spot can get a relative smooth surface.Almen strip with thickness 2.5mm was shocked as the preliminary verification test of residual stresses,and it is shown that excessive peening times is unavailable to thin-wall parts just as edge of fan blades.展开更多
基金financial support of project on reliability and life research of typical components in rail trains (K10TZ20P0500) of CRRC Zhuzhou Electric Locomotive Research Institute.
文摘To get a full understanding of hot extrusion,solid solution treatment and aging process on the Al−0.56Mg−0.63Si alloy,the microstructure and mechanical properties of a U-shaped profile were studied through optical microscopy,scanning electrical microscopy,transmission electrical microscopy,hardness,and tensile tests.The coarse equiaxed grains existed near the profile edge as a result of the dynamic recrystallization nucleation and exceeding growth during hot extrusion.The fibrous deformed and sub-structured grains located between the two coarse grain layers,due to the occurrence of work-hardening and dynamic recovery.Perpendicular needle β′′precipitates were distributed inside the grain,and obvious precipitates-free zone appeared after aging treatment.The tensile strength,yield strength and elongation of the aged Al−Mg−Si alloy U-shaped profile were no less than 279.4 MPa,258.6 MPa,and 21.6%,respectively.The fracture morphology showed dimple rupture characteristics.The precipitates and grain boundaries played key role in the strengthening contribution.
基金supported by the National Natural Science Foundation of China(Grant No 10775063)
文摘This paper reports that the transmission of O6＋ ions with energy of 150keV through capillaries in an uncoated Al2O3 membrane was measured, and agreements with previously reported results in general angular distribution of the transmitted ions and the transmission fractions as a function of the tilt angle well fitted to Gaussian-like functions were observed. Due tousing an uncoated capillary membrane, our φc is larger than that using a gold-coated one with a smaller value of Ep/q, which suggests a larger equilibrium charge Q∞ in our experiment. The observed special width variation with time and a larger width than that using a smaller Ep/q were qualitatively explained by using mean-field classical transport theory based on a classical-trajectory Monte Carlo simulation.
文摘The dendrite growth process during the solidification of the Al-4.5%Cu binary alloy was simulated using the phase-field model, proposed by Kim et al. Solute diffusion equation and heat transfer equation were solved simultaneously. The effects of the noise on the dendrite growth, solute and temperature profile in the undercooled alloy melt were investigated. The results indicate that the noise can trigger the growth of the secondary arms, and increase the highest temperature and solute concentration, but not influence the tip operating state. The solute and temperature gradients in the tip are the highest.
文摘The latest applications of laser shock processing were summarized in this paper,and laser peening with water confined layer has been applied to Ti6Al4V titanium alloy using Nd:glass pulse laser.The profile of plastic deformation and residual stresses on metal surface were studied with different laser power density.The investigation results show that peak depth of plastic deformation is in linear proportion to laser power density (5.75GW/cm2 to 9.5 GW/cm2),and maximal surface compressive residual stress is up to 375MPa at 8.25GW/cm2.It was ensured that the compressive residual stress field related to laser power density and shocked times.As spot overlapping ratio of 33%,the circle spot can get a relative smooth surface.Almen strip with thickness 2.5mm was shocked as the preliminary verification test of residual stresses,and it is shown that excessive peening times is unavailable to thin-wall parts just as edge of fan blades.
