Fig. 1. Microstructure of Ti-Al layered metal. The normal direction, transverse direction and rolling direction are hereafter denoted as ND, TD and RD, respectively.

Fig. 2. In-situ EBSD mappings of Ti-Al layered metal. The IPF mappings of Ti layer upon plastic strain of (a) 0%, (b) 1%, (c) 3%, (d) 10%. De-twinning was prevalent in Ti-Al layered metal during the uniaxial tension, as indicated by white arrows. The grain boundary misorientation mappings of Ti-Al layered metal upon plastic strain of (e) 0%, (f) 1%, (g) 3%, (h) 10%. De-twining corresponds to grain boundary misorientation of 84.7° ($\left\{ 10\bar{1}2 \right\}\langle 10\bar{1}\bar{1}\rangle $ extension twinning) as indicated by white arrows.

Fig. 3. In-situ microstructure evolution of Ti-Al layered metal upon plastic strain of (a) 0%, (b) 1%, (c) 3%, (d) 10%. The left column shows (0001) pole figures of Ti in Ti-Al layered metal at various strains. The right column showed the statistical distributions of misorientation angle for Ti in Ti-Al layered metal at various strains. The misorientation angles corresponding to $\left\{ 10\bar{1}2 \right\}\langle 10\bar{1}\bar{1}\rangle $ extension twinning, $\left\{ 11\bar{2}2 \right\}\langle 11\bar{2}\bar{3}\rangle $ contraction twinning, and $\left\{ 10\bar{1}1 \right\}\langle 10\bar{1}2\rangle $ contraction twinning were marked by pentagrams, squares, and circles, respectively.

Fig. 4. Twinning boundary length connected with $\left\{ 10\bar{1}2 \right\}\langle 10\bar{1}\bar{1}\rangle $ extension twinning and $\left\{ 11\bar{2}2 \right\}\langle 11\bar{2}\bar{3}\rangle $ contraction twinning of Ti in Ti-Al layered metal as a function of strain. The $\left\{ 10\bar{1}2 \right\}\langle 10\bar{1}\bar{1}\rangle $ extension twinning continued to de-twinning, and the de-twinning rate decreased with the increase of strain, while $\left\{ 11\bar{2}2 \right\}\langle 11\bar{2}\bar{3}\rangle $ contraction twinning only activated on the initial deformation stage.

Fig. 5. Inverse pole figures of Ti in Ti-Al layered metal along (a) RD, (b) ND, (c) TD. All Ti grains are indicated by small celadon circles, while the de-twinning twins and de-twinning parents were marked by red and navy circles, respectively. (d) Misorientation angle between the c-axes of de-twinned twins/parents and the ND. Misorientation angles exceeding 50° were prevalent for de-twinned twins, while the c-axes of de-twinned parents had a small angle with respect to the ND.

Fig. 6. In-situ de-twinning analysis via local Schmid factor. EBSD mappings at plastic strains of (a, d) 0%, (b, e) 10%. (c, f) Local Schmid factor for de-twinning of Twin 1–5 in (a) and (d) that takes ${{\sigma }_{\text{ND}}}$ into account.

Fig. 7. Effects of ${{\sigma }_{\text{TD}}}$ on local Schmid factor for de-twinning of (a) Twin 1, (b) Twin 2 and Twin 3, and (c) Twin 4 and Twin 5.