The crystallography of deformation kinking

Abstract

Kinking is a secondary deformation mode of crystalline materials being controlled by slip and often occurring as an accommodation mechanism for twins. However, it can also be considered to be a deformation mode in its own right. The composition plane and shear direction of a kink band can then be defined using the familiar K ₁, η₁ notation normally used to describe the crystallography of deformation twins. Equations for these elements, which for kinks are a function of the shear strain, are presented. Following the analogy with twinning, observed deformation kinking modes can be classified as type I, type II or compound. Results of detailed experimental studies of kinking in crystalline mercury and niobium have played an important role in developing this classification scheme which is based on the symmetry of the associated slip plane and direction. The need for further experimental studies on kinking is stressed and links with analyses of other intercrystalline boundaries discussed.