Connection between shear instability and amorphisation

Amorphous structures are formed whenever atomic species are not able to arrange according to a crystalline, long-range order. This can be obtained with various non-equilibrium techniques involving, for example, the rapid cooling of a melt as well as the accumulation of chemical and structural disorder in a solid. Irrespective of the microscopic mechanisms responsible for the amorphisation, it seems that the phenomenon is basically related to a fundamental topological instability. In this work, evidences are given supporting the hypothesis that amorphisation is essentially due to the occurrence of a mechanical shear instability.