Production of lattice vacancies in metals by deformation twinning

Abstract

Deformation twinning of fcc and bcc metals may lead to void formation. In a first step, hollow channels are formed at the intersection of twin lamellae. Such channels, known as “Rose channels”, were extensively studied in calcite by Gustav Rose and others in the 19th Century. In a second step, the sectioning of the Rose channels by slip results in voids and vacancy clusters. This two-step mechanism is thought to account for the recent electron-microscopy observations of Kiritani et al . on the formation of vacancy clusters by “plastic deformation without dislocations”. The so-far enigmatic abundance of vacancy clusters and the absence of self-interstitial clusters in the Kiritani experiments turn out to be natural consequences of the inherent asymmetry of twinning. †Dedicated to Professor Dr. Eckard Macherauch in honour of his 80th birthday on 30 September 2006