Abstract
It is shown that Paidar-Pope-Vitek (PPV) locks in superdislocations in L12ordered compounds have a higher energy than the glissile configuration. As a consequence, PPV locks can be formed only when the dissociation width d 0 of the superpartials is of atomic dimensions. When d 0 is of the order of a few b, locking by cross-slip on to a {010} plane, leading to a high-temperature flow stress peak, can still occur. The tension-compression asymmetry will, however, be different from that predicted by PPV.