Perfect and imperfect dislocations trailing phason faults in quasi-crystals were introduced using a simplified 2-dimensional aperiodic structure. Then, on the basis of observations of deformed specimens as well as in situ experiments in a transmission electron microscope, the motion of dislocations in icosahedral Al–Pd–Mn was shown to take place exclusively by climb. Under such conditions, the very high brittleness of Al–Pd–Mn at low and medium temperatures was proposed to be a consequence of the difficulty of glide, which itself appears to be an intrinsic property of the quasi-crystalline structure.

Transmission Electron Microscopy Study of Dislocation Motion in Icosahedral Al–Pd–Mn. F.Mompiou, D.Caillard: Materials Science and Engineering A, 2005, 400-401, 283-93