Nearly undamaged joints of electron beam welded(EBW)dual-phase Mg-8Li-3Al-2Zn-0.5Y alloy were achieved with joint coefficients exceeding 95%.All specimens were fractured at the base metal(BM),implying a significant de...Nearly undamaged joints of electron beam welded(EBW)dual-phase Mg-8Li-3Al-2Zn-0.5Y alloy were achieved with joint coefficients exceeding 95%.All specimens were fractured at the base metal(BM),implying a significant departure from conventional fracture modes of welded joints.The fusion zone(FZ)consists of ultrafine acicular α-Mg and equiaxed β-Li,with grain sizes reduced by approximately 90% and 80%,respectively,compared to the base metal.This results in a significant increase in microhardness of about 40%.A unique multiphase mixture was observed in the heat-affected zone(HAZ),which mainly consists of lamellar eutectoid structures,fine precipitates zone,and numerous fine Mg_(3)(Al,Zn)particles.This mixture was transformed from typical Li(Al,Zn)(a common softening phase)undergoing atomic diffusion and solid-state phase transformation during welding.It introduces a synergistic strengthening effect,making the heat-affected zone no longer the weakest part of the joint.This study provides valuable insights into the electron beam welding technology for Mg-Li alloys and offers theoretical support for manufacturing high-quality joints.展开更多
The ultra-light Mg–8Li–3Al–2Zn–0.5Y(LAZ832–0.5Y)thin wall parts with excellent performances were successfully fabricated by Gas Tungsten Arc Welding(GTAW)in this study.The microstructure of the top,middle and bot...The ultra-light Mg–8Li–3Al–2Zn–0.5Y(LAZ832–0.5Y)thin wall parts with excellent performances were successfully fabricated by Gas Tungsten Arc Welding(GTAW)in this study.The microstructure of the top,middle and bottom regions of the thin wall fabricated under various conditions was examined and the mechanical properties of these thin walls were tested.The results showed that much finer microstructure was obtained by GTAW than that made by conventional casting method.In the as-deposited samples,the needle-like shapedα-Mg phase emerged at the top of the thin wall whereas the bar-shapedα-Mg phase showed up in the middle and bottom regions of the thin wall due to the complex thermal history.The Al2Y phase was dispersed throughout bothα-Mg andβ-Li while the AlLi phase was mainly located in theβ-Li.The best combination of ultimate tensile strength(UTS),yield strength(YS)and elongation to fracture of the as-deposited thin wall were 218.9 MPa,171.4 MPa and 20.9%,respectively,which was manufactured under the optimal condition of 120 A 1800 mm/min 220 mm/min.After solid solution treatment at 350℃for 4 h,the UTS increased slightly by 13%but the YS increased significantly by 65%compared with the samples before solid solution.The solution of the AlLi phase was believed to be the main strengthening mechanism.It is interesting to note that the UTS and YS of the as-deposited sample was better than those of the as-cast sample while the opposite situation took place after solid solution treatment.展开更多
This study was conducted to discuss the effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5 Y（wt%） alloy, which was prepared by casting, and then homogenized and rolled...This study was conducted to discuss the effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5 Y（wt%） alloy, which was prepared by casting, and then homogenized and rolled at 200℃. The rolling process was conducted with 10% reduction per pass and five different accumulated strains, varying from 10% to 70%. The results indicate that the as-cast and as-rolled Mg-8Li-3Al-2Zn-0.5Y alloys are composed of α-Mg, β-Li, AlLi and Al;Y phases. After rolling process,anisotropic microstructure was observed. a-Mg phase got elongated in both rolling direction and transverse direction with the addition of rolling strain. Consequently, the strength of the alloy in both directions was notably improved whereas the elongation declined, mainly caused by strain hardening and dispersion strengthening. The tensile properties of the as-rolled alloys in the RD, no matter the YS, UTS or the elongation, are higher than those of the TD due to their larger deformation strain and significant anisotropy in the hcp α-Mg phase. In addition, the fracture and strengthening mechanism of the tested alloys were also investigated systematically.展开更多
Y_2(p-CH_3C_6H_4COO)_6(C_(12)H_8N_2)_2, Mr=1349.08, triclinic, space group P, a=13.00(3), b=19.743(2), c=12.754(3)A, α=97.94(1), β=106.24(2), γ=91.66(1)°, V=3177(1)~3, Z=2, Dc=1.41gcm^(-3), λ(MoKα)=0.71069, ...Y_2(p-CH_3C_6H_4COO)_6(C_(12)H_8N_2)_2, Mr=1349.08, triclinic, space group P, a=13.00(3), b=19.743(2), c=12.754(3)A, α=97.94(1), β=106.24(2), γ=91.66(1)°, V=3177(1)~3, Z=2, Dc=1.41gcm^(-3), λ(MoKα)=0.71069, μ=18.92 cm^(-1), F(ooo)=1384, T=295K, final R=0.073 for 6504 observed reflections with Ⅰ>36(Ⅰ). There are two nonidentical binuclear molecules with different bridging connection patterns in a cell. One has four bridging carboxyl groups bound two Y(Ⅲ) ions and another only has two. The Y-Y distance is 4.196 for the former and 5.302 for the latter respectively.展开更多
A new kind of aluminium-based alloy part amorphous/part crystalline, can be produced directlyby rapid quenching of the liquid. These materials have a novel structure of nanometer-sizedcrystals in an amorphous matrix a...A new kind of aluminium-based alloy part amorphous/part crystalline, can be produced directlyby rapid quenching of the liquid. These materials have a novel structure of nanometer-sizedcrystals in an amorphous matrix and quite remarkable mechanical properties. The materialscan be considered to be nanophase composites. In this work Al88Ni10Y2 and Al88Ni8Y4 (atpct) nanophase composites consisting of a nanoscale dispersion of fcc-Al crystallites uniformlydispersed in an amorphous matrix, have been produced by melt-spinning. They have much highermicrohardness HV than fully amorphous alloys with the same composition. while retaining goodbending ductility The volume fraction, crystallite size and distribution of the fcc-Al phase havebeen estimated by DSC. X-ray diffraction and TEM. lt is found that the microstructure andproperties of the nanophase composites are very sensitive to the composition and the quenchingconditions. lncreasing the Y contedt and decreasing the Ni content at a given Al content givesmuch smaller dispersed nanophase aluminium crystallites. The volume fraction and crystallitesize of the fcc-Al phase increase with a decrease of wheel speed (quenching rate). The effectsof Y and Ni contents on the ease of formaticn of the nanophase composites are discussed. Theorigins of the novel mechanical properties are also considered.展开更多
基金financially supported by the National Defense Basic Research Program(No.JCKY2023204A005)Project of High Modulus Magnesium Alloy Forgings(JXXT-2023-014hbza)+1 种基金Research Program of Joint Research Center of Advanced Spaceflight Technologies(No.USCAST2023-3)Major Scientific and Technological Innovation Project of Luoyang(No.2201029A).
文摘Nearly undamaged joints of electron beam welded(EBW)dual-phase Mg-8Li-3Al-2Zn-0.5Y alloy were achieved with joint coefficients exceeding 95%.All specimens were fractured at the base metal(BM),implying a significant departure from conventional fracture modes of welded joints.The fusion zone(FZ)consists of ultrafine acicular α-Mg and equiaxed β-Li,with grain sizes reduced by approximately 90% and 80%,respectively,compared to the base metal.This results in a significant increase in microhardness of about 40%.A unique multiphase mixture was observed in the heat-affected zone(HAZ),which mainly consists of lamellar eutectoid structures,fine precipitates zone,and numerous fine Mg_(3)(Al,Zn)particles.This mixture was transformed from typical Li(Al,Zn)(a common softening phase)undergoing atomic diffusion and solid-state phase transformation during welding.It introduces a synergistic strengthening effect,making the heat-affected zone no longer the weakest part of the joint.This study provides valuable insights into the electron beam welding technology for Mg-Li alloys and offers theoretical support for manufacturing high-quality joints.
基金supported by the National Key Research and Development Program of China(No.2021YFB3701303)Foundation Strengthening Plan Technical Field Fund(No.2021-JJ-0112)+1 种基金Major Scientific and Technological Innovation Project of Luoyang(No.2201029A)National Natural Science Foundation of China(No.U2037601).
文摘The ultra-light Mg–8Li–3Al–2Zn–0.5Y(LAZ832–0.5Y)thin wall parts with excellent performances were successfully fabricated by Gas Tungsten Arc Welding(GTAW)in this study.The microstructure of the top,middle and bottom regions of the thin wall fabricated under various conditions was examined and the mechanical properties of these thin walls were tested.The results showed that much finer microstructure was obtained by GTAW than that made by conventional casting method.In the as-deposited samples,the needle-like shapedα-Mg phase emerged at the top of the thin wall whereas the bar-shapedα-Mg phase showed up in the middle and bottom regions of the thin wall due to the complex thermal history.The Al2Y phase was dispersed throughout bothα-Mg andβ-Li while the AlLi phase was mainly located in theβ-Li.The best combination of ultimate tensile strength(UTS),yield strength(YS)and elongation to fracture of the as-deposited thin wall were 218.9 MPa,171.4 MPa and 20.9%,respectively,which was manufactured under the optimal condition of 120 A 1800 mm/min 220 mm/min.After solid solution treatment at 350℃for 4 h,the UTS increased slightly by 13%but the YS increased significantly by 65%compared with the samples before solid solution.The solution of the AlLi phase was believed to be the main strengthening mechanism.It is interesting to note that the UTS and YS of the as-deposited sample was better than those of the as-cast sample while the opposite situation took place after solid solution treatment.
基金supported by the National Key Research and Development Program of China(No.2016YFB0301004)the National Natural Science Foundation of China(No.51771115)+1 种基金the Science and Technology Innovation Project(No.009-031-001)Research Program of Joint Research Center of Advanced Spaceflight Technologies(Nos.USCAST2015-25 and USCAST2016-18)
文摘This study was conducted to discuss the effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5 Y（wt%） alloy, which was prepared by casting, and then homogenized and rolled at 200℃. The rolling process was conducted with 10% reduction per pass and five different accumulated strains, varying from 10% to 70%. The results indicate that the as-cast and as-rolled Mg-8Li-3Al-2Zn-0.5Y alloys are composed of α-Mg, β-Li, AlLi and Al;Y phases. After rolling process,anisotropic microstructure was observed. a-Mg phase got elongated in both rolling direction and transverse direction with the addition of rolling strain. Consequently, the strength of the alloy in both directions was notably improved whereas the elongation declined, mainly caused by strain hardening and dispersion strengthening. The tensile properties of the as-rolled alloys in the RD, no matter the YS, UTS or the elongation, are higher than those of the TD due to their larger deformation strain and significant anisotropy in the hcp α-Mg phase. In addition, the fracture and strengthening mechanism of the tested alloys were also investigated systematically.
文摘Y_2(p-CH_3C_6H_4COO)_6(C_(12)H_8N_2)_2, Mr=1349.08, triclinic, space group P, a=13.00(3), b=19.743(2), c=12.754(3)A, α=97.94(1), β=106.24(2), γ=91.66(1)°, V=3177(1)~3, Z=2, Dc=1.41gcm^(-3), λ(MoKα)=0.71069, μ=18.92 cm^(-1), F(ooo)=1384, T=295K, final R=0.073 for 6504 observed reflections with Ⅰ>36(Ⅰ). There are two nonidentical binuclear molecules with different bridging connection patterns in a cell. One has four bridging carboxyl groups bound two Y(Ⅲ) ions and another only has two. The Y-Y distance is 4.196 for the former and 5.302 for the latter respectively.
文摘A new kind of aluminium-based alloy part amorphous/part crystalline, can be produced directlyby rapid quenching of the liquid. These materials have a novel structure of nanometer-sizedcrystals in an amorphous matrix and quite remarkable mechanical properties. The materialscan be considered to be nanophase composites. In this work Al88Ni10Y2 and Al88Ni8Y4 (atpct) nanophase composites consisting of a nanoscale dispersion of fcc-Al crystallites uniformlydispersed in an amorphous matrix, have been produced by melt-spinning. They have much highermicrohardness HV than fully amorphous alloys with the same composition. while retaining goodbending ductility The volume fraction, crystallite size and distribution of the fcc-Al phase havebeen estimated by DSC. X-ray diffraction and TEM. lt is found that the microstructure andproperties of the nanophase composites are very sensitive to the composition and the quenchingconditions. lncreasing the Y contedt and decreasing the Ni content at a given Al content givesmuch smaller dispersed nanophase aluminium crystallites. The volume fraction and crystallitesize of the fcc-Al phase increase with a decrease of wheel speed (quenching rate). The effectsof Y and Ni contents on the ease of formaticn of the nanophase composites are discussed. Theorigins of the novel mechanical properties are also considered.
