How do dislocations allow metals to deform?

In materials science, dislocations are line defects within a crystal structure that serve as the fundamental mechanism for metal plasticity and deformation.12

Metals deform through a process known as slip, where layers of atoms slide over one another. Rather than requiring the simultaneous breaking of all atomic bonds across a plane—which would require immense force—dislocations allow this movement to occur incrementally. When a mechanical stress is applied, these defects move through the crystal lattice, effectively shifting the atomic planes one row at a time. This motion facilitates plastic flow at much lower shear stresses than would be theoretically required for a perfect crystal.3421

While dislocations enable deformation, they also play a critical role in strengthening metals. Through processes like cold-working (e.g., rolling or hammering), the generation and movement of dislocations cause them to intersect and form tangles. These tangles act as barriers that inhibit further slip, a phenomenon known as work hardening, which increases the metal's yield stress.34