摘要
As multiple{11■2}twin variants are often formed during deformation in hexagonal close-packed (hcp)titanium, the twin-twin interaction structure has a profound influence on mechanical properties. In this paper, the twin-twin interaction structures of the{11■2}contraction twin in cold-rolled commercial purity titanium were studied by using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Formation of the{11■2}twin variants was found to deviate the rank of Schmid factor,and the non-Schmid behavior was explained by the high-angle grain boundary nucleation mechanism.All the observed twin-twin pairs manifested a quilted-looking structure, which consists of the incoming twins being arrested by the obstacle twins. Furthermore, the quilted-looking{11■2}twin-twin boundary was revealed by TEM and high resolution TEM observations. De-twinning, lattice rotation and curved twin boundary were observed in the obstacle twin due to the twin-twin reaction with the impinging twin. A twin-twin interaction mechanism for the{11■2}twin variants was proposed in terms of the dislocation dissociation, which will enrich the understanding for the propagation of twins and twinning-induced hardening in hcp metals and alloys.
As multiple {11■2} twin variants are often formed during deformation in hexagonal close-packed(hcp)titanium, the twin-twin interaction structure has a profound influence on mechanical properties. In this paper, the twin-twin interaction structures of the {11■2} contraction twin in cold-rolled commercial purity titanium were studied by using electron backscatter diffraction(EBSD) and transmission electron microscopy(TEM). Formation of the {11■2} twin variants was found to deviate the rank of Schmid factor,and the non-Schmid behavior was explained by the high-angle grain boundary nucleation mechanism.All the observed twin-twin pairs manifested a quilted-looking structure, which consists of the incoming twins being arrested by the obstacle twins. Furthermore, the quilted-looking {11■2} twin-twin boundary was revealed by TEM and high resolution TEM observations. De-twinning, lattice rotation and curved twin boundary were observed in the obstacle twin due to the twin-twin reaction with the impinging twin. A twin-twin interaction mechanism for the {11■2} twin variants was proposed in terms of the dislocation dissociation, which will enrich the understanding for the propagation of twins and twinning-induced hardening in hcp metals and alloys.
基金
financially supported by the National Natural Science Foundation of China (Grants Nos.11374028 and U1330112)
the Key Project of Beijing Natural Science Foundation (No.KZ201310005002)