Väärähiladislokaatiot

Väärähiladislokaatiot, also known as anti-phase boundaries or APBs, are planar defects that can occur in ordered alloys and crystals. They form when a crystal or alloy that has a specific atomic arrangement, such as a superlattice, is created or processed in a way that disrupts this precise ordering. This disruption leads to regions within the crystal where the atoms are shifted relative to their ideal positions, creating an "out-of-phase" boundary.

These boundaries are not dislocations in the traditional sense of crystal lattice defects, as they do not involve the shear of atomic planes. Instead, they represent a change in the crystallographic phase or ordering. For example, in an ordered alloy A-B, a väärähiladislokaatio might separate a region where the A atoms are on one set of lattice sites from a region where the B atoms occupy those same sites, with the other atom type occupying the alternative sites.

The formation of väärähiladislokaatiot can occur during various processes, including rapid cooling or annealing of ordered alloys, or even during the initial growth of certain crystals. They can significantly influence the mechanical and physical properties of materials. For instance, they can act as barriers to dislocation motion, thereby increasing hardness and strength. However, they can also be sites for crack initiation or propagation, potentially reducing ductility and toughness. The presence and characteristics of väärähiladislokaatiot are often studied using techniques such as transmission electron microscopy.