The present study is focused on the influence of a routine step, washing, following the preparation of calcined rare earth exchanged Y zeolite, on its hydrothermal stability. The hydrothermal stability of REY products...The present study is focused on the influence of a routine step, washing, following the preparation of calcined rare earth exchanged Y zeolite, on its hydrothermal stability. The hydrothermal stability of REY products, which were washed by different reagents, was observed and characterized by XRD, ICP, NMR, etc. The results reveal that the amount and the chemical type of the acidic media used for washing can significantly influence the content of remaining non-framework aluminum (NFA) and consequently further affect the hydrothermal stability of the washed REY products. The content of remaining non-framework aluminum can be well correlated with the crystallinity of REY products.展开更多
A new method was proposed for preparing AZ31/1060 composite plates with a corrugated interface,which involved cold-pressing a corrugated surface on the Al plate and then hot-pressing the assembled Mg/Al plate.The resu...A new method was proposed for preparing AZ31/1060 composite plates with a corrugated interface,which involved cold-pressing a corrugated surface on the Al plate and then hot-pressing the assembled Mg/Al plate.The results show that cold-pressing produces intense plastic deformation near the corrugated surface of the Al plate,which promotes dynamic recrystallization of the Al substrate near the interface during the subsequent hot-pressing.In addition,the initial corrugation on the surface of the Al plate also changes the local stress state near the interface during hot pressing,which has a large effect on the texture components of the substrates near the corrugated interface.The construction of the corrugated interface can greatly enhance the shear strength by 2−4 times due to the increased contact area and the strong“mechanical gearing”effect.Moreover,the mechanical properties are largely depended on the orientation relationship between corrugated direction and loading direction.展开更多
The effects of artificial aging(T6)on the creep resistance with tensile stresses in the range of 50−80 MPa at 175℃were investigated for an extruded Mg−1.22Al−0.31Ca−0.44Mn(wt.%)alloy.The Guinier-Preston(G.P.)zones pr...The effects of artificial aging(T6)on the creep resistance with tensile stresses in the range of 50−80 MPa at 175℃were investigated for an extruded Mg−1.22Al−0.31Ca−0.44Mn(wt.%)alloy.The Guinier-Preston(G.P.)zones primarily precipitate in the sample aged at 200℃for 1 h(T6-200℃/1h),while the Al_(2)Ca phases mainly precipitate in the sample aged at 275℃for 8 h(T6-275℃/8h).The T6-200℃/1h sample exhibits excellent creep resistance,with a steady-state creep rate one order of magnitude lower than that of the T6-275℃/8h sample.The abnormally high stress exponent(~8.2)observed in the T6-200℃/1h sample is associated with the power-law breakdown mechanism.TEM analysis illuminates that the creep mechanism for the T6-200℃/1h sample is cross-slip between basal and prismatic dislocations,while the T6-275℃/8h sample exhibits a mixed mechanism of dislocation cross-slip and climb.Compared with the Al_(2)Ca phase,the dense G.P.zones effectively impede dislocation climb and glide during the creep process,demonstrating superior creep resistance of the T6-200℃/1h sample.展开更多
The evolution of the S'precipitate in Al−Cu−Mg alloy was investigated using transmission electron microscopy(TEM),high-angle annular dark-field scanning transmission electron microscopy(HAADF−STEM),molecular dynam...The evolution of the S'precipitate in Al−Cu−Mg alloy was investigated using transmission electron microscopy(TEM),high-angle annular dark-field scanning transmission electron microscopy(HAADF−STEM),molecular dynamics(MD)simulations,and other analytical techniques.The precipitation behavior during different aging stages of the supersaturated solid solution formed after rapid cold punching was focused,which induces rapid dissolution of precipitates.The findings reveal that the precipitation sequence is significantly influenced by aging temperature.At higher aging temperatures,which mitigate lattice distortion in the matrix,the precipitation sequence follows the conventional path.Conversely,at lower aging temperatures,where lattice distortion persists,the sequence deviates,suppressing the formation of Guinier−Preston−Bagaryatsky(GPB)zones.MD simulations confirm that the variations in solute atom diffusion rates at different aging temperatures lead to the differences in the S'phase precipitation sequence.展开更多
The Sn−2Al filler metal was utilized to bond W90 tungsten heavy alloys by the ultrasonic-assisted coating technology in atmospheric environment at 250℃.The effects of ultrasonic power and ultrasonic time on microstru...The Sn−2Al filler metal was utilized to bond W90 tungsten heavy alloys by the ultrasonic-assisted coating technology in atmospheric environment at 250℃.The effects of ultrasonic power and ultrasonic time on microstructure and interfacial strength of Sn−2Al/W90 interface were investigated.The ultrasound improved the wettability of Sn−2Al filler metal on W90 surface.As the ultrasonic power increased and ultrasonic time increased,the size of Al phase in seam decreased.The maximum value of Sn−2Al/W90 interfacial strength reached 30.1 MPa.Based on the acoustic pressure simulation and bubble dynamics,the intensity of cavitation effect was proportional to ultrasonic power.The generated high temperature and high pressure by cavitation effect reached 83799.6 K and 1.26×10^(14) Pa,respectively.展开更多
The dependence of shrinkage porosities on microstructure characteristics of Mg−12Al alloy was investigated.The distribution,morphology,size,and number density of shrinkage porosities were analyzed under different cool...The dependence of shrinkage porosities on microstructure characteristics of Mg−12Al alloy was investigated.The distribution,morphology,size,and number density of shrinkage porosities were analyzed under different cooling rates.The relationship between shrinkage porosities and microstructure characteristics was discussed in terms of temperature conditions,feeding channel characteristics,and feeding capacity.Further,the feeding behavior of the residual liquid phase in the solid skeleton was quantified by introducing permeability.Results show a strong correlation between the solid microstructure skeleton and shrinkage porosity characteristics.An increase in permeability corresponds to a declining number density of shrinkage porosities.This study aims to provide a more complete understanding how to reduce shrinkage porosities by controlling microstructure characteristics.展开更多
文摘The present study is focused on the influence of a routine step, washing, following the preparation of calcined rare earth exchanged Y zeolite, on its hydrothermal stability. The hydrothermal stability of REY products, which were washed by different reagents, was observed and characterized by XRD, ICP, NMR, etc. The results reveal that the amount and the chemical type of the acidic media used for washing can significantly influence the content of remaining non-framework aluminum (NFA) and consequently further affect the hydrothermal stability of the washed REY products. The content of remaining non-framework aluminum can be well correlated with the crystallinity of REY products.
基金supported by Guangdong Major Project of Basic and Applied Basic Research, China (No. 2020B0301030006)Fundamental Research Funds for the Central Universities, China (No. SWU-XDJH202313)+1 种基金Chongqing Postdoctoral Science Foundation Funded Project, China (No. 2112012728014435)the Chongqing Postgraduate Research and Innovation Project, China (No. CYS23197)。
文摘A new method was proposed for preparing AZ31/1060 composite plates with a corrugated interface,which involved cold-pressing a corrugated surface on the Al plate and then hot-pressing the assembled Mg/Al plate.The results show that cold-pressing produces intense plastic deformation near the corrugated surface of the Al plate,which promotes dynamic recrystallization of the Al substrate near the interface during the subsequent hot-pressing.In addition,the initial corrugation on the surface of the Al plate also changes the local stress state near the interface during hot pressing,which has a large effect on the texture components of the substrates near the corrugated interface.The construction of the corrugated interface can greatly enhance the shear strength by 2−4 times due to the increased contact area and the strong“mechanical gearing”effect.Moreover,the mechanical properties are largely depended on the orientation relationship between corrugated direction and loading direction.
基金supported by the National Natural Science Foundation of China (Nos. 52175322, 52271031)the Natural Science Foundation of Jilin Province, China (No. SKL202302015)。
文摘The effects of artificial aging(T6)on the creep resistance with tensile stresses in the range of 50−80 MPa at 175℃were investigated for an extruded Mg−1.22Al−0.31Ca−0.44Mn(wt.%)alloy.The Guinier-Preston(G.P.)zones primarily precipitate in the sample aged at 200℃for 1 h(T6-200℃/1h),while the Al_(2)Ca phases mainly precipitate in the sample aged at 275℃for 8 h(T6-275℃/8h).The T6-200℃/1h sample exhibits excellent creep resistance,with a steady-state creep rate one order of magnitude lower than that of the T6-275℃/8h sample.The abnormally high stress exponent(~8.2)observed in the T6-200℃/1h sample is associated with the power-law breakdown mechanism.TEM analysis illuminates that the creep mechanism for the T6-200℃/1h sample is cross-slip between basal and prismatic dislocations,while the T6-275℃/8h sample exhibits a mixed mechanism of dislocation cross-slip and climb.Compared with the Al_(2)Ca phase,the dense G.P.zones effectively impede dislocation climb and glide during the creep process,demonstrating superior creep resistance of the T6-200℃/1h sample.
基金supported by the China Scholarship Council (CSC) Local Cooperation Program (No. 202308430176)the National Natural Science Foundation of China (No. 52271177)the Hunan Provincial Natural Science Foundation Regional Joint Fund, China (No. 2023JJ50173)。
文摘The evolution of the S'precipitate in Al−Cu−Mg alloy was investigated using transmission electron microscopy(TEM),high-angle annular dark-field scanning transmission electron microscopy(HAADF−STEM),molecular dynamics(MD)simulations,and other analytical techniques.The precipitation behavior during different aging stages of the supersaturated solid solution formed after rapid cold punching was focused,which induces rapid dissolution of precipitates.The findings reveal that the precipitation sequence is significantly influenced by aging temperature.At higher aging temperatures,which mitigate lattice distortion in the matrix,the precipitation sequence follows the conventional path.Conversely,at lower aging temperatures,where lattice distortion persists,the sequence deviates,suppressing the formation of Guinier−Preston−Bagaryatsky(GPB)zones.MD simulations confirm that the variations in solute atom diffusion rates at different aging temperatures lead to the differences in the S'phase precipitation sequence.
基金supported by the National Natural Science Foundation of China(Nos.52105330,52175307)the Natural Science Foundation of Shandong Province,China(No.ZR2023JQ021)。
文摘The Sn−2Al filler metal was utilized to bond W90 tungsten heavy alloys by the ultrasonic-assisted coating technology in atmospheric environment at 250℃.The effects of ultrasonic power and ultrasonic time on microstructure and interfacial strength of Sn−2Al/W90 interface were investigated.The ultrasound improved the wettability of Sn−2Al filler metal on W90 surface.As the ultrasonic power increased and ultrasonic time increased,the size of Al phase in seam decreased.The maximum value of Sn−2Al/W90 interfacial strength reached 30.1 MPa.Based on the acoustic pressure simulation and bubble dynamics,the intensity of cavitation effect was proportional to ultrasonic power.The generated high temperature and high pressure by cavitation effect reached 83799.6 K and 1.26×10^(14) Pa,respectively.
基金financially supported by the National Key Research and Development Program of China(No.2021YFB3701000)the National Natural Science Foundation of China(Nos.52471118,52101125,U2037601,and U21A2048)Young Elite Scientists Sponsorship Program by CAST,China(No.2022QNRC001)。
文摘The dependence of shrinkage porosities on microstructure characteristics of Mg−12Al alloy was investigated.The distribution,morphology,size,and number density of shrinkage porosities were analyzed under different cooling rates.The relationship between shrinkage porosities and microstructure characteristics was discussed in terms of temperature conditions,feeding channel characteristics,and feeding capacity.Further,the feeding behavior of the residual liquid phase in the solid skeleton was quantified by introducing permeability.Results show a strong correlation between the solid microstructure skeleton and shrinkage porosity characteristics.An increase in permeability corresponds to a declining number density of shrinkage porosities.This study aims to provide a more complete understanding how to reduce shrinkage porosities by controlling microstructure characteristics.
