Magnesium alloys usually exhibit poor ductility attributed to their intrinsic hexagonal close-packed(hcp)structure,which fails to provide sufficient independent slip systems for homogeneous deformation.Here we demonst...Magnesium alloys usually exhibit poor ductility attributed to their intrinsic hexagonal close-packed(hcp)structure,which fails to provide sufficient independent slip systems for homogeneous deformation.Here we demonstrate that multiple deformation mechanisms can be activated with increasing tensile strain in a fine-grained Mg-3Gd with a weak basal texture.<c+a>slip,tension twinning and compression/double twinning exhibit a high orientation dependence at an early stage of deformation,whereas the orientation dependence becomes less obvious with further increasing strain.The high work hardening rate at the strain of 2%–5%is accompanied by the significant increase of<c+a>slip and tension twinning activities.The fine microstructure strongly restricts the activation and growth of twinning,resulting in a slow exhaust of tension twinning and thin compression twins.The restriction of twinning and the activation of profuse<c+a>slip near grain/twin boundaries,relaxing the stress concentration,sustain the homogeneous deformation to a high strain.展开更多
Duplex-structured Mg-7Li-2Al-1.5Sn alloys with high strength were fabricated and their strengthening mechanism was investigated.The Mg-7Li-2Al-1.5Sn alloys were prepared by casting and extruded at the temperature of 5...Duplex-structured Mg-7Li-2Al-1.5Sn alloys with high strength were fabricated and their strengthening mechanism was investigated.The Mg-7Li-2Al-1.5Sn alloys were prepared by casting and extruded at the temperature of 533 K with an extrusion ratio of 25:1.The microstructure and mechanical properties of Mg-7Li-2Al-1.5Sn alloys were systematically investigated by OM,XRD,SEM,TEM,and tensile tests.The results show that Mg-7Li-2Al-1.5Sn alloys are mainly composed ofα-Mg,β-Li,LiMgAl_(2),Mg_(2)Sn and Li_(2)MgSn phases.The yield strength(YS),ultimate tensile strength(UTS)and elongation(EL)of the extruded alloy at room temperature reach 250 MPa,324 MPa and 11.9%,respectively.A lot of Sn-rich precipitates(Mg_(2)Sn and Li_(2)MgSn)are precipitated during extrusion with an average size of∼14 nm,which is beneficial to the grain refinement.Dynamic recrystallization occurs during hot deformation and the nanoprecipitates effectively refine the dynamic recrystallized(DRXed)grains.Besides,the residual dislocations existed in DRXed and un-DRXed grains result in the dislocation strengthening in the extruded alloy.Mg7Li-2Al-1.5Sn alloys possess excellent high-temperature mechanical properties with the YS,UTS and EL of 200 MPa,237 MPa and 26.7%at 423 K,respectively.Sn-rich precipitates with good thermal stability can effectively prevent grain growth,which is good for the improvement of the high-temperature performance of Mg-Li-Al-Sn alloy.展开更多
基金This project has received funding from the National Key Research and Development Program(2021YFB3702100)TY was supported by a research grant(VIL50197)from VILLUM FONDEN。
文摘Magnesium alloys usually exhibit poor ductility attributed to their intrinsic hexagonal close-packed(hcp)structure,which fails to provide sufficient independent slip systems for homogeneous deformation.Here we demonstrate that multiple deformation mechanisms can be activated with increasing tensile strain in a fine-grained Mg-3Gd with a weak basal texture.<c+a>slip,tension twinning and compression/double twinning exhibit a high orientation dependence at an early stage of deformation,whereas the orientation dependence becomes less obvious with further increasing strain.The high work hardening rate at the strain of 2%–5%is accompanied by the significant increase of<c+a>slip and tension twinning activities.The fine microstructure strongly restricts the activation and growth of twinning,resulting in a slow exhaust of tension twinning and thin compression twins.The restriction of twinning and the activation of profuse<c+a>slip near grain/twin boundaries,relaxing the stress concentration,sustain the homogeneous deformation to a high strain.
基金the financial support from the Chongqing Research Program of Basic Research and Frontier Technology(Project No.cstc2019jcyj-msxm X0306)the National Key Research and Development Program of China(Project No.2016YFB0700403&Project No.2016YFB0301100)+1 种基金the fundamental Research funds for Central Universities(Project No.2021CDJJMRH001 and 2020CDJDPT001)the 111 Project(Project No.B16007)by the Ministry of Education and the State Administration of Foreign Experts Affairs of China。
文摘Duplex-structured Mg-7Li-2Al-1.5Sn alloys with high strength were fabricated and their strengthening mechanism was investigated.The Mg-7Li-2Al-1.5Sn alloys were prepared by casting and extruded at the temperature of 533 K with an extrusion ratio of 25:1.The microstructure and mechanical properties of Mg-7Li-2Al-1.5Sn alloys were systematically investigated by OM,XRD,SEM,TEM,and tensile tests.The results show that Mg-7Li-2Al-1.5Sn alloys are mainly composed ofα-Mg,β-Li,LiMgAl_(2),Mg_(2)Sn and Li_(2)MgSn phases.The yield strength(YS),ultimate tensile strength(UTS)and elongation(EL)of the extruded alloy at room temperature reach 250 MPa,324 MPa and 11.9%,respectively.A lot of Sn-rich precipitates(Mg_(2)Sn and Li_(2)MgSn)are precipitated during extrusion with an average size of∼14 nm,which is beneficial to the grain refinement.Dynamic recrystallization occurs during hot deformation and the nanoprecipitates effectively refine the dynamic recrystallized(DRXed)grains.Besides,the residual dislocations existed in DRXed and un-DRXed grains result in the dislocation strengthening in the extruded alloy.Mg7Li-2Al-1.5Sn alloys possess excellent high-temperature mechanical properties with the YS,UTS and EL of 200 MPa,237 MPa and 26.7%at 423 K,respectively.Sn-rich precipitates with good thermal stability can effectively prevent grain growth,which is good for the improvement of the high-temperature performance of Mg-Li-Al-Sn alloy.
