On July 7, Prof. W. J. Clegg from the University of Cambridge held a workshop on "Plastic flow and fracture in non-metallic crystals" at the Chair of Materials Chemistry of the RWTH Aachen University. The workshop took place from 9 to 12 o' clock and aimed at the description of the nature of plastic flow in non-metallic crystals. In hard coatings, the stress required to move a dislocation is determined by the increases in the misfit energy of the dislocation as it moves through the crystal lattice, known as the lattice resistance. Clegg also explained why the dislocations came to exist and how they can move below the Peierls stress.