Deformation of a Burgers oriented bimetallic bicrystal of alpha-beta (Ti-13Mn)

Abstract

The deformation behavior of a Burgers oriented α-β-Ti-13Mn bimetallic bicrystal was studied at two plastic strains, 0.52 and 2.08 pct. Two single crystals, α and β, each corresponding to the orientation of its respective bicrystal component were also investigated. The stress axes were$[1\bar 7610]_\alpha$ and [1218]_β. The interface planes were$(\bar 1\bar 3580)_\alpha$ and$(\bar 334)_\beta$ and lay in the x’-z’ plane. The deformation behavior of the a component differed from that of the a single crystal because of plastically induced stresses,T _y’z’ ,T _x’z’ ,T _x’y’ , and σ _x’x’ . Prismatic slip and$\{ 11\bar 21\}$ twinning were found in the single crystal α whereas the bicrystal revealed additionally pyramidal andc + a slip, the latter at the interface. Slip on the front and back surfaces was different and both thec + a and twinning systems acted to maintain compatibility. Slip in the β single crystal and the β bicrystal component were quite similar. However, there were differences in the intensity and amount of primary slip, (231)$[\bar 11\bar 1{\text{]}}$, on the front and back surfaces. The diminished amount of (231)$[\bar 11\bar 1{\text{]}}$ slip on the back surface was due to plastically induced stresses, and on the front surface the primary slip cross slipped to$(1\bar 2\bar 3)[\bar 11\bar 1]$ slip which triggeredc + a slip in α. On the back surface the dominant slip system was$(21\bar 1){\text{ }}[\bar 11\bar 1{\text{]}}$ which acted in response to the plastically induced stresses. An approximate calculation revealed that the interface deformation zone had about twice the flow stress of the average bicrystal stress.