Line tension of screw dislocations on cross-slip planes

Abstract

In this letter the line tension associated with screw dislocations is considered. First, it is shown that screw dislocations can be identified with negative line tensions on various cross-slip planes in cubic crystals; analytical or numerical conditions for negative line tension are given. Secondly, the relative magnitudes of the line tension on relevant cross-slip planes are calculated. The line tension on 〈100〉 and 〈111〉 screw dislocations is found to be fully independent of the cross-slip plane, whereas that of 〈110〉 screw dislocations depends sensitively on the cross-slip plane and is at a maximum on the cube cross-slip plane for most materials. The implications of a negative line tension are discussed and a locking mechanism of elastically unstable screw dislocation is proposed.