Nanopowder consolidation under high strain rate shock compression is a potential method for synthesizing and processing bulk nanomaterials,and a thorough investigation of the deformation and its underlying mechanisms ...Nanopowder consolidation under high strain rate shock compression is a potential method for synthesizing and processing bulk nanomaterials,and a thorough investigation of the deformation and its underlying mechanisms in consolidation is of great engineering significance.We conduct non-equilibrium molecular dynamics(NEMD)simulation and X-ray diffraction(XRD)simulation to systematically study shock-induced deformation and the corresponding mechanisms during the consolidation of nanopowdered Mg(NP-Mg).Two different deformation modes govern the shock consolidation in NP-Mg,i.e.,deformation twinning at up≤1.5 km s^(-1)and structural disordering,at up≥2.0 km s^(-1).They accelerate the collapse of nanopores and void compaction,giving rise to the final consolidation of NP-Mg.Three types of deformation twinning are emitted in NP-Mg,i.e.,the extension twinning for{1121}(1126),and{1102}〈1101>,and the compression{1122}(1123)twinning.They are prompted via coupling atomic shuffles and slips.Deformation twinning prefers to occur within the grains as shock along<1120>or its approaching direction(A-and B-type grains),originated from the high-angle grain boundaries(HAGB)at compression stage.They are inhibited within the ones as shocking along<0001>and the approaching ones(C-and D-type grains).The release and tension loading facilitates the reversible and irreversible detwinning,for the extension and compression twinning,respectively,within the A-and B-type grains.It also contributes to a compression-tension asymmetry for twinning,i.e.,release and tension induced extension twinning within the C-and D-type grains.The subsequent spallation is mediated by GB sliding and GB-induced stacking faults at up≤1.5 km s^(-1),and structural disordering at up≥2.0 km s^(-1).展开更多
The interaction between{112}<111>deformation twinning and grain boundary in coaxial polycrystalline tantalum under shock compression was studied with molecular dynamics simulation under different grain pair miso...The interaction between{112}<111>deformation twinning and grain boundary in coaxial polycrystalline tantalum under shock compression was studied with molecular dynamics simulation under different grain pair misorientation angles(MA)and geometric compatibility factor(m’).Generally,in the coaxial polycrystal,the value of MA determines the occurrence of twin transfer(TT)or twin blockage(TB),i.e.,twin transfer occurs at MA≤29°with twin blockage otherwise.Under TT,the value of m’affects the selection of twin variants.,i.e.,the twin system with a larger m’is easier to active.The morphology of twin pairs is ruler-shaped and lenticular under TT and TB,respectively,with different thickening mechanisms,including grain boundary dislocation emission.展开更多
基金financially supported by the Natural Science Foundation(NSF)of China(Nos.11802092 and U2230401)NSF of Hunan Province(Nos.2019JJ50221,2019JJ40127,2020JJ5260,and 2020JJ4375)+5 种基金the Funding of the Hunan Education Department Project(Nos.20A248 and 22B0225)the Double first-class construction project of Hunan Agricultural University(No.SYL2019063)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20230682)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20230682)the Postgraduate Scientific Research Innovation Project of Hunan Agricultural University(No.2023XC019)We also acknowledge the support of the computation platform of the National Super Computer Center in Changsha(NSCC).
文摘Nanopowder consolidation under high strain rate shock compression is a potential method for synthesizing and processing bulk nanomaterials,and a thorough investigation of the deformation and its underlying mechanisms in consolidation is of great engineering significance.We conduct non-equilibrium molecular dynamics(NEMD)simulation and X-ray diffraction(XRD)simulation to systematically study shock-induced deformation and the corresponding mechanisms during the consolidation of nanopowdered Mg(NP-Mg).Two different deformation modes govern the shock consolidation in NP-Mg,i.e.,deformation twinning at up≤1.5 km s^(-1)and structural disordering,at up≥2.0 km s^(-1).They accelerate the collapse of nanopores and void compaction,giving rise to the final consolidation of NP-Mg.Three types of deformation twinning are emitted in NP-Mg,i.e.,the extension twinning for{1121}(1126),and{1102}〈1101>,and the compression{1122}(1123)twinning.They are prompted via coupling atomic shuffles and slips.Deformation twinning prefers to occur within the grains as shock along<1120>or its approaching direction(A-and B-type grains),originated from the high-angle grain boundaries(HAGB)at compression stage.They are inhibited within the ones as shocking along<0001>and the approaching ones(C-and D-type grains).The release and tension loading facilitates the reversible and irreversible detwinning,for the extension and compression twinning,respectively,within the A-and B-type grains.It also contributes to a compression-tension asymmetry for twinning,i.e.,release and tension induced extension twinning within the C-and D-type grains.The subsequent spallation is mediated by GB sliding and GB-induced stacking faults at up≤1.5 km s^(-1),and structural disordering at up≥2.0 km s^(-1).
基金financially supported by the Key-Area Re-search and Development Program of GuangDong Province(No.2019B010941001)National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(No.6142902220301)+1 种基金Shanghai Engineering Research Center of High-Performance Medical Device Materials(No.20DZ2255500)the Major Science and Technology Infrastructure Project of Material Genome Bigscience Facilities Platform supported by Municipal Development and Reform Commission of Shenzhen.
文摘The interaction between{112}<111>deformation twinning and grain boundary in coaxial polycrystalline tantalum under shock compression was studied with molecular dynamics simulation under different grain pair misorientation angles(MA)and geometric compatibility factor(m’).Generally,in the coaxial polycrystal,the value of MA determines the occurrence of twin transfer(TT)or twin blockage(TB),i.e.,twin transfer occurs at MA≤29°with twin blockage otherwise.Under TT,the value of m’affects the selection of twin variants.,i.e.,the twin system with a larger m’is easier to active.The morphology of twin pairs is ruler-shaped and lenticular under TT and TB,respectively,with different thickening mechanisms,including grain boundary dislocation emission.
