Observation and interpretation of grain boundary compatibility effects in Fe-3.3wt%Si bicrystals

Abstract

Plastic deformation in compression was studied on Fe-3.3wt%Si bicrystals containing a non-symmetrical grain boundary with the 〈100〉 rotation axis and the misorientation angle of 37° (reciprocal density of coincidence sites Σ5). Traces of operating slip systems were observed on specimen surfaces as well as inside the specimens on the {100} cuts after dislocation etching. The experimental results were interpreted on the basis of a model where the elastic anisotropy of the component crystals is fully taken into account. The observations are in agreement with the prediction that the additional compatibility stresses increase with the angle between the 〈100〉 rotation axis and the loading axis lying in the grain boundary plane. The activation of slip systems with lower Schmid factor referred to the applied stress agrees with the results of the theoretical model. Geometrical criteria for the slip transfer from a plastically deformed grain to the adjacent grain are discussed. It is shown that the slip transfer can occur only when the angle between the intersection lines of the slip planes with the grain boundary plane is small.