An embedded-atom potential was used to study the lattice resistance to dislocation motion in pure Al under pressure. The sign and magnitude of the pressure effect upon the Peierls stress were obtained by means of direct atomistic calculation (molecular statics), and were in agreement with experimental data. A significant transient dilatancy was observed to be associated with the activated state of dislocation motion. This supported the previous suggestion that pressure-dependent slip in metals was due to the interaction, of a transient activation dilatancy of moving dislocations, with the external pressure. In the case of pure Al, the tension-compression yield-strength differential was equal to only 0.3%, but the effect was significant for the quantitative modelling of the behaviour of high-strength Al alloys in tension and compression.

An Atomistic Dislocation Mechanism of Pressure-Dependent Plastic Flow in Aluminium. V.V.Bulatov, O.Richmond, M.V.Glazov: Acta Materialia, 1999, 47[12], 3507-14