In this study,an AlCu/AlMgSc bimetallic alloy is prepared using a dual-wire arc direct energy deposition method and a triple heterogeneous microstructure(fine/coarse equiaxed grains/columnar grains)is constructed.Addi...In this study,an AlCu/AlMgSc bimetallic alloy is prepared using a dual-wire arc direct energy deposition method and a triple heterogeneous microstructure(fine/coarse equiaxed grains/columnar grains)is constructed.Additionally,a quantitative comparative analysis of the deformation behavior of triple and dual heterogeneous microstructures during interrupted tensile testing is conducted,with emphasis on the effects of grain morphology and size on the tensile deformation mechanisms in the heterogeneous microstructure.Compared with the AlCu alloy with a double heterogeneous microstructure(equiaxed/columnar grain),the AlCu/AlMgSc bimetallic alloy exhibits a higher ultimate tensile strength of 301.4±7.9 MPa,a yield strength of 181.3±1.4 MPa,and an elongation of 9.7%±1.3%,which correspond to increases by 19.4%,21.2%,and 24.4%,respectively.Interrupted tensile testing is performed and a quasi-in-situ approach is employed to investigate the plastic deformation mechanisms of the triple heterogeneous microstructure during tensile deformation.The density of geometrically necessary dislocations(GNDs)in the fine equiaxed grains and the rate of GND accumulation during deformation,surpassed those observed in coarse equiaxed and columnar grains.Furthermore,in micrometer-sized equiaxed grains,the ability to accumulate GNDs decreases as the equiaxed grain size increases,and the equiaxed grains exhibit a higher capacity to accumulate GNDs compared with columnar grains.The triple heterogeneous microstructure provides a more favorable environment for trapping GNDs,thus resulting in enhanced strength and plastic deformation capabilities.This study offers guidance for the formulation and engineering application of heterogeneous microstructure alloys with diverse grain morphologies and multiple length scales.Additionally,novel approaches are introduced to enhance the strength and ductility of Al alloys.展开更多
A lMgSc是航空航天等尖端领域的一种新型轻合金结构材料。利用江苏大学强激光研究所的高功率钕玻璃激光器对A lMgSc合金板进行了激光冲击成形实验研究,用TaylorHobson三坐标表面轮廓测量机测量了冲击后板料的变形量以及表面的粗糙度。...A lMgSc是航空航天等尖端领域的一种新型轻合金结构材料。利用江苏大学强激光研究所的高功率钕玻璃激光器对A lMgSc合金板进行了激光冲击成形实验研究,用TaylorHobson三坐标表面轮廓测量机测量了冲击后板料的变形量以及表面的粗糙度。实验结果表明:约束层的刚度越大,激光诱导的冲击波力越大,板料的变形量越大;当只有激光能量大于某一临界值(该值与材料本身有关)时,板料的变形量才随着凹模孔径的增大而增大;板料的变形量随着半径方向的冲击波压力变化而不同。最后介绍了压力测量原理及其公式。展开更多
To improve the understanding of coupling effect between dynamic recrystallization(DRX)behaviors and flow behaviors of as-cast AlCu4 SiMg, a finite element(FE) simulation equipped with the models of DRX evolution was i...To improve the understanding of coupling effect between dynamic recrystallization(DRX)behaviors and flow behaviors of as-cast AlCu4 SiMg, a finite element(FE) simulation equipped with the models of DRX evolution was implemented. A series of isothermal compression tests were performed primarily on a Gleeble-3500 thermo-mechanical simulator in a temperature range of 648-748 K and a strain rate range of 0.01-10 s-1.According to the measured true stress-strain data,the strain hardening rate curves(dσ/dε versus σ) were plotted to identify the critical strains for DRX initiation(εc). By further derivation of the related material constants, the DRX volume fraction equation and the strain for 50% DRX(ε0.5) equation were solved. Accordingly, the aforementioned DRX equations were implanted into the FE model to conduct a series of simulations for the isothermal compression tests. The results show that during the evolution of DRX volume fraction at a fixed strain rate, the strain required for the same amount of DRX volume fraction increases with decreasing temperature. In contrast, at a fixed temperature, it increases with increasing strain rate. Ultimately, the DRX kinetics model of AlCu4 SiMg alloy and the consequence of the FE analysis were validated by microstructure observations.展开更多
Additive manufacturing of aluminum(Al)alloys has attracted significant attention in the aerospace industry.However,achieving ultrahigh-strength(>500 MPa)Al alloys remains challenging due to their intrinsic poor pri...Additive manufacturing of aluminum(Al)alloys has attracted significant attention in the aerospace industry.However,achieving ultrahigh-strength(>500 MPa)Al alloys remains challenging due to their intrinsic poor printability.Here,we report a novel hybrid additive manufacturing(HAM)approach to process ultrahigh-strength AlMgSc alloy,which combines laser powder bed fusion(LPBF)with interlayer ultrasonic shot peening(USP).The results show that the interlayer ultrasonic shot peening depth reached∼700μm,leading to almost full density and residual stress convection from tension to compression.The HAM method promotes equiaxed grain formation and refines grain due to grain recrystallizations.Interestingly,the HAM followed by aging treatment tailors the hierarchically multi-gradient structures,inhibits Mg element intragranular segregation,and promotes the multi-nanoprecipitates(e.g.Al_(3)(Sc,Zr)and Al_(6)Mn)precipitation.Remarkably,the HAM followed by aging treatment achieves yield strength of 609 MPa and breaks elongation of 7.5%,demonstrating ultrahigh strength and good ductility compared with other Al alloys manufactured by AM and forging as reported in the literature.The strength enhancement mechanisms in this AlMgSc alloy are discussed.The high-density Al_(3)(Sc,Zr)precipitates are the main strengthening contributor,and unique hetero-deformation induced(HDI)strengthening(originates from the heterogeneous microstructures)further enhances the strength of the material.This work highlights a novel approach for processing complex-structured ultrahigh strength Al alloy components by hybrid additive manufacturing.展开更多
基金supported by the National Natu-ral Science Foundation of China(No.52205414)the Young Elite Scientists Sponsorship Program by CAST(No.2021QNRC001)+3 种基金the Advance Research Projects in the Field of Manned Spaceflight,China Manned Space Agency,China(No.040302)the Shang-hai Aerospace Science and Technology Innovation Fund Project,the Shanghai Academy of Spaceflight Technology,China(No.SAST2018-066)the 73rd batch of China Postdoctoral Science Foun-dation General Financial Support(No.2023MD734199)the Shaanxi Provincial Natural Science Basic Research Program(No.2023-JC-QN-0551).
文摘In this study,an AlCu/AlMgSc bimetallic alloy is prepared using a dual-wire arc direct energy deposition method and a triple heterogeneous microstructure(fine/coarse equiaxed grains/columnar grains)is constructed.Additionally,a quantitative comparative analysis of the deformation behavior of triple and dual heterogeneous microstructures during interrupted tensile testing is conducted,with emphasis on the effects of grain morphology and size on the tensile deformation mechanisms in the heterogeneous microstructure.Compared with the AlCu alloy with a double heterogeneous microstructure(equiaxed/columnar grain),the AlCu/AlMgSc bimetallic alloy exhibits a higher ultimate tensile strength of 301.4±7.9 MPa,a yield strength of 181.3±1.4 MPa,and an elongation of 9.7%±1.3%,which correspond to increases by 19.4%,21.2%,and 24.4%,respectively.Interrupted tensile testing is performed and a quasi-in-situ approach is employed to investigate the plastic deformation mechanisms of the triple heterogeneous microstructure during tensile deformation.The density of geometrically necessary dislocations(GNDs)in the fine equiaxed grains and the rate of GND accumulation during deformation,surpassed those observed in coarse equiaxed and columnar grains.Furthermore,in micrometer-sized equiaxed grains,the ability to accumulate GNDs decreases as the equiaxed grain size increases,and the equiaxed grains exhibit a higher capacity to accumulate GNDs compared with columnar grains.The triple heterogeneous microstructure provides a more favorable environment for trapping GNDs,thus resulting in enhanced strength and plastic deformation capabilities.This study offers guidance for the formulation and engineering application of heterogeneous microstructure alloys with diverse grain morphologies and multiple length scales.Additionally,novel approaches are introduced to enhance the strength and ductility of Al alloys.
基金Project(cstc2016jcyjA0335)supported by Chongqing Foundation and Frontier Research,ChinaProject(P2017-020)supported by Open Fund Project of State Key Laboratory of Materials Processing and Die&Mould Technology,China
文摘To improve the understanding of coupling effect between dynamic recrystallization(DRX)behaviors and flow behaviors of as-cast AlCu4 SiMg, a finite element(FE) simulation equipped with the models of DRX evolution was implemented. A series of isothermal compression tests were performed primarily on a Gleeble-3500 thermo-mechanical simulator in a temperature range of 648-748 K and a strain rate range of 0.01-10 s-1.According to the measured true stress-strain data,the strain hardening rate curves(dσ/dε versus σ) were plotted to identify the critical strains for DRX initiation(εc). By further derivation of the related material constants, the DRX volume fraction equation and the strain for 50% DRX(ε0.5) equation were solved. Accordingly, the aforementioned DRX equations were implanted into the FE model to conduct a series of simulations for the isothermal compression tests. The results show that during the evolution of DRX volume fraction at a fixed strain rate, the strain required for the same amount of DRX volume fraction increases with decreasing temperature. In contrast, at a fixed temperature, it increases with increasing strain rate. Ultimately, the DRX kinetics model of AlCu4 SiMg alloy and the consequence of the FE analysis were validated by microstructure observations.
基金supported by the National Natural Science Foundation of China(Grant No:52475484)National Key R&D Program of China(Grant No:2022YFB4600800)the 2022 MTC Young Individual Research Grants(Grant No:M22K3c0097)under the Singapore RIE 2025 Plan.
文摘Additive manufacturing of aluminum(Al)alloys has attracted significant attention in the aerospace industry.However,achieving ultrahigh-strength(>500 MPa)Al alloys remains challenging due to their intrinsic poor printability.Here,we report a novel hybrid additive manufacturing(HAM)approach to process ultrahigh-strength AlMgSc alloy,which combines laser powder bed fusion(LPBF)with interlayer ultrasonic shot peening(USP).The results show that the interlayer ultrasonic shot peening depth reached∼700μm,leading to almost full density and residual stress convection from tension to compression.The HAM method promotes equiaxed grain formation and refines grain due to grain recrystallizations.Interestingly,the HAM followed by aging treatment tailors the hierarchically multi-gradient structures,inhibits Mg element intragranular segregation,and promotes the multi-nanoprecipitates(e.g.Al_(3)(Sc,Zr)and Al_(6)Mn)precipitation.Remarkably,the HAM followed by aging treatment achieves yield strength of 609 MPa and breaks elongation of 7.5%,demonstrating ultrahigh strength and good ductility compared with other Al alloys manufactured by AM and forging as reported in the literature.The strength enhancement mechanisms in this AlMgSc alloy are discussed.The high-density Al_(3)(Sc,Zr)precipitates are the main strengthening contributor,and unique hetero-deformation induced(HDI)strengthening(originates from the heterogeneous microstructures)further enhances the strength of the material.This work highlights a novel approach for processing complex-structured ultrahigh strength Al alloy components by hybrid additive manufacturing.
