Mechanical metamaterials are architectured cellular materials with unusual properties.Herein we report another type of metal mechanical metamaterials-their elastic admissible strain(EAS)is on the order of 0.1,compared...Mechanical metamaterials are architectured cellular materials with unusual properties.Herein we report another type of metal mechanical metamaterials-their elastic admissible strain(EAS)is on the order of 0.1,compared to about 0.01 for common metallic materials.Four conditions are required for a metal mechanical metamaterial to achieve this super EAS:(i)bending-dominated deformation;(ii)low density;(iii)an appropriate lattice topology,and(iv)an intrinsically high EAS for the lattice strut constituent material.The findings of this work extend perspectives on metal mechanical metamaterials.展开更多
Alpha-beta(α-β)titanium alloys such as Ti-6Al-4V(wt.%,here-after the same)and Ti-6Al-2Sn-4Zr-2Mo fabricated by fusion-based additive manufacturing(AM)typically exhibit a strong columnar prior-βgrain structure.These...Alpha-beta(α-β)titanium alloys such as Ti-6Al-4V(wt.%,here-after the same)and Ti-6Al-2Sn-4Zr-2Mo fabricated by fusion-based additive manufacturing(AM)typically exhibit a strong columnar prior-βgrain structure.These columnar prior-βgrains with their001along the build direction not only lead to solidification tex-ture but also cause subsequentα-phase textures[1].The forma-tion of theseα-phase textures is a consequence of theβ→αtransformation obeying the Burgers orientation relationship(BOR)[1-5],which results in[0001]of theα-phase being orientated at about either 45°or 0°relative to the horizontal.They affect the deformation behaviour and mechanical properties[1,6].Defined by the BOR,a singleβ-phase grain can bring forth 12α-phase vari-ants[2,7],leading to significant microstructural intricacy.Theseα-phase variants do not form randomly in eachβ-phase grain.Rather,their formation displays specific crystallographic features,known asα-variant selection,which is common in Ti alloys.In an extreme case,α-variant selection can lead to the formation of a singleα-phase crystal through anα→β→αtransformation cy-cle[8,9].展开更多
基金the China Scholarship Council(CSC)for a CSC scholarship(No.201706230108)Funding from the National Natural Science Foundation of China(No.51971145)and the Australian Research Council(Nos.DP200102666 and No.DE230101344)is acknowledged.
文摘Mechanical metamaterials are architectured cellular materials with unusual properties.Herein we report another type of metal mechanical metamaterials-their elastic admissible strain(EAS)is on the order of 0.1,compared to about 0.01 for common metallic materials.Four conditions are required for a metal mechanical metamaterial to achieve this super EAS:(i)bending-dominated deformation;(ii)low density;(iii)an appropriate lattice topology,and(iv)an intrinsically high EAS for the lattice strut constituent material.The findings of this work extend perspectives on metal mechanical metamaterials.
基金supported by the Australian Research Council (ARC) through DP180103205
文摘Alpha-beta(α-β)titanium alloys such as Ti-6Al-4V(wt.%,here-after the same)and Ti-6Al-2Sn-4Zr-2Mo fabricated by fusion-based additive manufacturing(AM)typically exhibit a strong columnar prior-βgrain structure.These columnar prior-βgrains with their001along the build direction not only lead to solidification tex-ture but also cause subsequentα-phase textures[1].The forma-tion of theseα-phase textures is a consequence of theβ→αtransformation obeying the Burgers orientation relationship(BOR)[1-5],which results in[0001]of theα-phase being orientated at about either 45°or 0°relative to the horizontal.They affect the deformation behaviour and mechanical properties[1,6].Defined by the BOR,a singleβ-phase grain can bring forth 12α-phase vari-ants[2,7],leading to significant microstructural intricacy.Theseα-phase variants do not form randomly in eachβ-phase grain.Rather,their formation displays specific crystallographic features,known asα-variant selection,which is common in Ti alloys.In an extreme case,α-variant selection can lead to the formation of a singleα-phase crystal through anα→β→αtransformation cy-cle[8,9].
