Twinning and phase transformations in Zr crack tips

MARGARITA RUDA; DIANA FARKAS; GRACIELA BERTOLINO

COMPUTATIONAL MATERIALS SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2010 vol. 49 p. 743 - 750

0927-0256

We present atomistic studies of the deformation mechanisms occurring in the crack-tip region duringlow temperature fracture of hcp Zr. Static simulations of mode I fracture in Zr single crystals were per-formed using empiric embedded atom (EAM) potentials. Cracks were introduced in six different crystal-lographic orientations. For each crack orientation two different crack-propagation directions werechosen. Plasticity on the crack tip in single crystal hcp Zr depends strongly on the orientation of the crack.Several competing processes are involved, including the phase transformation to the bcc structure. Twin-ning and dislocation emission are the other major mechanisms responsible for ductility. For the caseswhere the transformation to bcc was observed, a significant improvement in ductility results from thetransformation.