In composite solid propellants with high aluminum(Al)content and low burning rate,incomplete combustion of the Al powder may occur.In this study,varying lithium(Li)content in Al-Li alloy powder was utilized instead of...In composite solid propellants with high aluminum(Al)content and low burning rate,incomplete combustion of the Al powder may occur.In this study,varying lithium(Li)content in Al-Li alloy powder was utilized instead of pure aluminum particles to mitigate agglomeration and enhance the combustion efficiency of solid propellants(Combustion efficiency herein refers to the completeness of metallic fuel oxidation,quantified as the ratio of actual-to-theoretical energy released during combustion)with high Al content and low burning rates.The impact of Al-Li alloy with different Li contents on combustion and agglomeration of solid propellant was investigated using explosion heat,combustion heat,differential thermal analysis(DTA),thermos-gravimetric analysis(TG),dynamic high-pressure combustion test,ignition experiment of small solid rocket motor(SRM)tests,condensation combustion product collection,and X-ray diffraction techniques(XRD).Compared with pure Al,Al-Li alloys exhibit higher combustion heat,which contributes to improved combustion efficiency in Al-Li alloy-containing propellants.DTA and TG analyses demonstrated higher reactivity and lower ignition temperatures for Al-Li alloys.High-pressure combustion experiments at 5 MPa showed that Al-Li alloy fuel significantly decreases combustion agglomeration.The results from theφ75 mm andφ165 mm SRM and XRD tests further support this finding.This study provides novel insights into the combustion and agglomeration behaviors of high-Al,low-burning-rate composite solid propellants and supports the potential application of Al-Li alloys in advanced propellant formulations.展开更多
Friction stir lap welding of AA2195 Al-Li alloy and Ti alloy was conducted to investigate the formation,microstructure,and mechanical properties of the joints.Results show that under different welding parameters,with ...Friction stir lap welding of AA2195 Al-Li alloy and Ti alloy was conducted to investigate the formation,microstructure,and mechanical properties of the joints.Results show that under different welding parameters,with the decrease in welding heat input,the weld surface is smoother.The Ti/Al joint interface is flat without obvious Ti and Al mixed structure,and the hook structure is not formed under optimal parameters.Due to the enhanced breaking effect of the stirring head,the hook structural defects and intermetallic compounds are more likely to form at the Ti/Al interface at high rotational speed of 1000 r/min,thereby deteriorating the mechanical properties of joints.Decreasing the heat input is beneficial to hardness enhancement of the aluminum alloy in the weld nugget zone.Under the optimal parameters of rotation speed of 800 r/min and welding speed of 120 mm/min,the maximum tensile shear strength of joint is 289 N/mm.展开更多
The intergranular corrosion behavior of 2050 Al-Li alloy subjected to non-isothermal aging(NIA)treatment with varying pre-deformation amounts was investigated.Results indicate that the resistance to intergranular corr...The intergranular corrosion behavior of 2050 Al-Li alloy subjected to non-isothermal aging(NIA)treatment with varying pre-deformation amounts was investigated.Results indicate that the resistance to intergranular corrosion improves with increasing pre-deformation amouts.However,when the pre-deformation amount reaches 20%,the corrosion resistance deteriorates.Microstructural analyses via transmission electron microscopy(TEM)and electron backscatter diffraction(EBSD)reveal that as pre-deformation amount increases,the fraction of high-angle grain boundaries(HAGBs)decreases,while the proportion of low-angle grain boundaries(LAGBs)increases.This change provides additional nucleation sites for precipitates,leading to a reduction in T1 phase size and an increase in T1 phase density.The finer T1 phases contribute to a lower localized potential difference within the grains,slowering corrosion propagation.Furthermore,during corrosion,preferential dissolution of Li results in Cu enrichment along grain boundaries,which further reduces the intergranular corrosion resistance.展开更多
Friction stir additive manufacturing(FSAM)is an innovative additive manufacturing(AM)method.The various heat treatment conditions of aluminum-lithium alloys using this method have not been widely discussed.In this stu...Friction stir additive manufacturing(FSAM)is an innovative additive manufacturing(AM)method.The various heat treatment conditions of aluminum-lithium alloys using this method have not been widely discussed.In this study,the microstructure evolution and mechanical properties of FSAM 2195 aluminum-lithium alloy in different heat treatment conditions(T3 and T8)were investigated.The results demonstrated that the heat treatment state of 2195 Al-Li alloys was minimally influenced by FSAM as the FSAM temperature exceeded the solid solution temperature.After conducting a single-pass FSAM experiment,a notable grain refinement was observed in the nugget zone(NZ)region compared to the base material(BM).The average grain size of the 2195-T3 alloy decreased from 6.1 to 2.9µm,while the proportion of high-angle grain boundaries increased from 16.5%to 43.9%.Similarly,the average grain size of the 2195-T8 alloy decreased from 8.9 to 2.8µm,with an increase in high-angle grain boundary from 37.6%to 59.2%.The tensile strength of the 2195-T3 Al-Li alloy reached 466 and 478 MPa in the NZ of single-pass and lap experiments,respectively.In comparison,the tensile strength of the 2195-T8 Al-Li alloy in the NZ could reach 452 and 481 MPa in single-pass and lap experiments,respectively.These results demonstrate the significant improvements in microstructure and mechanical properties were achieved through the FSAM process.展开更多
The microstructural evolution of banded 5A90 A1-Li alloy during superplastic deformation at 475℃ with an initial strain rate of 8× 10^-4 S^-1 was studied using EBSD technique. The results showed that, before def...The microstructural evolution of banded 5A90 A1-Li alloy during superplastic deformation at 475℃ with an initial strain rate of 8× 10^-4 S^-1 was studied using EBSD technique. The results showed that, before deformation, the grain shape appeared to be banded, the most grain boundaries belonged to low-angle boundaries, and the initial sheet had a dominate of { 110}（112） brass texture. During deformation, there were grain growth, grain shape change, misorientation increasing and textural weakening. The fraction of high-angle boundaries increased rapidly once the flow stress reached the peak value. Corresponding deformation mechanism for various stages of deformation was suggested. Dislocation activity was the dominant mechanism in the first stage, then dynamic recrystallization occurred, and grain rotation was expected as an accommodation for grain boundary sliding （GBS）. At large strains, GBS was the main mechanism.展开更多
基金the National Natural Science Foundation of China(Grant No.U2441263)for financial support of this work。
文摘In composite solid propellants with high aluminum(Al)content and low burning rate,incomplete combustion of the Al powder may occur.In this study,varying lithium(Li)content in Al-Li alloy powder was utilized instead of pure aluminum particles to mitigate agglomeration and enhance the combustion efficiency of solid propellants(Combustion efficiency herein refers to the completeness of metallic fuel oxidation,quantified as the ratio of actual-to-theoretical energy released during combustion)with high Al content and low burning rates.The impact of Al-Li alloy with different Li contents on combustion and agglomeration of solid propellant was investigated using explosion heat,combustion heat,differential thermal analysis(DTA),thermos-gravimetric analysis(TG),dynamic high-pressure combustion test,ignition experiment of small solid rocket motor(SRM)tests,condensation combustion product collection,and X-ray diffraction techniques(XRD).Compared with pure Al,Al-Li alloys exhibit higher combustion heat,which contributes to improved combustion efficiency in Al-Li alloy-containing propellants.DTA and TG analyses demonstrated higher reactivity and lower ignition temperatures for Al-Li alloys.High-pressure combustion experiments at 5 MPa showed that Al-Li alloy fuel significantly decreases combustion agglomeration.The results from theφ75 mm andφ165 mm SRM and XRD tests further support this finding.This study provides novel insights into the combustion and agglomeration behaviors of high-Al,low-burning-rate composite solid propellants and supports the potential application of Al-Li alloys in advanced propellant formulations.
基金National Natural Science Foundation of China(52275349)Key Research and Development Program of Shandong Province(2021ZLGX01)。
文摘Friction stir lap welding of AA2195 Al-Li alloy and Ti alloy was conducted to investigate the formation,microstructure,and mechanical properties of the joints.Results show that under different welding parameters,with the decrease in welding heat input,the weld surface is smoother.The Ti/Al joint interface is flat without obvious Ti and Al mixed structure,and the hook structure is not formed under optimal parameters.Due to the enhanced breaking effect of the stirring head,the hook structural defects and intermetallic compounds are more likely to form at the Ti/Al interface at high rotational speed of 1000 r/min,thereby deteriorating the mechanical properties of joints.Decreasing the heat input is beneficial to hardness enhancement of the aluminum alloy in the weld nugget zone.Under the optimal parameters of rotation speed of 800 r/min and welding speed of 120 mm/min,the maximum tensile shear strength of joint is 289 N/mm.
基金supported by the Postdoctoral Fellowship Program of CPSF,China(No.GZC20242033)the National Science and Technology Research Program of China(No.JPPT2023PXY01).
文摘The intergranular corrosion behavior of 2050 Al-Li alloy subjected to non-isothermal aging(NIA)treatment with varying pre-deformation amounts was investigated.Results indicate that the resistance to intergranular corrosion improves with increasing pre-deformation amouts.However,when the pre-deformation amount reaches 20%,the corrosion resistance deteriorates.Microstructural analyses via transmission electron microscopy(TEM)and electron backscatter diffraction(EBSD)reveal that as pre-deformation amount increases,the fraction of high-angle grain boundaries(HAGBs)decreases,while the proportion of low-angle grain boundaries(LAGBs)increases.This change provides additional nucleation sites for precipitates,leading to a reduction in T1 phase size and an increase in T1 phase density.The finer T1 phases contribute to a lower localized potential difference within the grains,slowering corrosion propagation.Furthermore,during corrosion,preferential dissolution of Li results in Cu enrichment along grain boundaries,which further reduces the intergranular corrosion resistance.
基金Project(U22A20190)supported by International Science and Technology Cooperation under the National Natural Science Foundation of ChinaProjects(U2241248,52205379)supported by the National Natural Science Foundation of ChinaProject(BE2023026)supported by Jiangsu Provincial Key Research and Development Program and Nanjing Science and Technology Innovation Project for Overseas Scholars,China。
文摘Friction stir additive manufacturing(FSAM)is an innovative additive manufacturing(AM)method.The various heat treatment conditions of aluminum-lithium alloys using this method have not been widely discussed.In this study,the microstructure evolution and mechanical properties of FSAM 2195 aluminum-lithium alloy in different heat treatment conditions(T3 and T8)were investigated.The results demonstrated that the heat treatment state of 2195 Al-Li alloys was minimally influenced by FSAM as the FSAM temperature exceeded the solid solution temperature.After conducting a single-pass FSAM experiment,a notable grain refinement was observed in the nugget zone(NZ)region compared to the base material(BM).The average grain size of the 2195-T3 alloy decreased from 6.1 to 2.9µm,while the proportion of high-angle grain boundaries increased from 16.5%to 43.9%.Similarly,the average grain size of the 2195-T8 alloy decreased from 8.9 to 2.8µm,with an increase in high-angle grain boundary from 37.6%to 59.2%.The tensile strength of the 2195-T3 Al-Li alloy reached 466 and 478 MPa in the NZ of single-pass and lap experiments,respectively.In comparison,the tensile strength of the 2195-T8 Al-Li alloy in the NZ could reach 452 and 481 MPa in single-pass and lap experiments,respectively.These results demonstrate the significant improvements in microstructure and mechanical properties were achieved through the FSAM process.
基金Project(51205419)supported by the National Natural Science Foundation of China
文摘The microstructural evolution of banded 5A90 A1-Li alloy during superplastic deformation at 475℃ with an initial strain rate of 8× 10^-4 S^-1 was studied using EBSD technique. The results showed that, before deformation, the grain shape appeared to be banded, the most grain boundaries belonged to low-angle boundaries, and the initial sheet had a dominate of { 110}（112） brass texture. During deformation, there were grain growth, grain shape change, misorientation increasing and textural weakening. The fraction of high-angle boundaries increased rapidly once the flow stress reached the peak value. Corresponding deformation mechanism for various stages of deformation was suggested. Dislocation activity was the dominant mechanism in the first stage, then dynamic recrystallization occurred, and grain rotation was expected as an accommodation for grain boundary sliding （GBS）. At large strains, GBS was the main mechanism.
