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].
