Crystallographic orientation dependent fracture behavior in tantalum single crystals

Abstract

We report crystallographic orientation dependent fracture behavior in tantalum single crystals with the tensile axes oriented close to [100], [110] and [111] directions. Three tantalum single crystals were deformed in quasi-static, uniaxial tension and their fracture surfaces were characterized. To understand different deformation modes and failure mechanisms, crystal plasticity-finite element (CP-FE) simulations were performed. Both experiments and CP-FE simulations showed strong strain localization and shear banding in the ~[100] specimen, little rotation and profuse necking in the ~[110] specimen, and significant crystal rotations associated with shear-dominated behavior in the ~[111] single crystal. In addition, voids were observed in fracture surfaces of ~[100] and ~[111] single crystals while the ~[110] specimen was void-free. The failure processes of these single crystals showed that dislocation boundaries are necessary for void nucleation in pure tantalum. This work demonstrates strong effects of crystallographic orientations in failure behaviors.