slip activity The main methods to identify the active slip system involve either slip trace analysis of single crystals or polycrystals, using diffraction techniques such as neutron diffraction and high angular resolution electron backscatter diffraction elastic strain analysis, or Transmission electron microscopy diffraction imaging of dislocations. In slip trace analysis, only the slip plane is measured, and the slip direction is inferred. In zirconium, for example, this enables the identification of slip activity on a basal, prism, or 1st/2nd order pyramidal plane. In the case of a 1st-order pyramidal plane trace, the slip could be in either 〈𝑎〉 or 〈𝑐 + 𝑎〉 directions; slip trace analysis cannot discriminate between these. Diffraction-based studies measure the residual dislocation content instead of the slipped dislocations, which is only a good approximation for systems that accumulate networks of geometrically necessary dislocations, such as Face-centred cubic polycrystals. In low-symmetry crystals such as hexagonal zirconium, there could be regions of the predominantly single slip where geometrically necessary dislocations may not necessarily accumulate. Residual dislocation content does not distinguish between glissile and sessile dislocations. Glissile dislocations contribute to slip and hardening, but sessile dislocations contribute only to latent hardening. Diffraction methods cannot generally resolve the slip plane of a residual dislocation. For example, in Zr, the screw components of 〈𝑎〉 dislocations could slip on prismatic, basal, or 1st-order pyramidal planes. Similarly, 〈𝑐 + 𝑎〉 screw dislocations could slip on either 1st or 2nd order pyramidal planes. See also Miller indices Persistent slip bands References External links An online tutorial on slip, explained on DoITPoMS Materials science