Abstract
The pressure dependence of the yield stress in solute strengthened aluminium alloys is investigated by first
principle calculations. The solute elements studied are magnesium, silicon and copper. A fixed boundary cluster
model is employed to calculate the interaction energies between the edge dislocation and the solutes, while
simultaneously controlling the hydrostatic pressure in the system. The results show a systematic increase in yield
stress with increasing hydrostatic pressure for all solute elements. The calculated pressure dependence is in
qualitative agreement with experiments, but underestimated quantitatively. It is suggested that the experimentally observed pressure dependence is caused by both the static and the transient dilatancy of dislocations. In
contrast to magnesium and copper atoms, silicon atoms are found to interact non-elastically with dislocations
within the core field, indicating that the favourable position for the silicon atoms is in the distorted sites in the
matrix.
principle calculations. The solute elements studied are magnesium, silicon and copper. A fixed boundary cluster
model is employed to calculate the interaction energies between the edge dislocation and the solutes, while
simultaneously controlling the hydrostatic pressure in the system. The results show a systematic increase in yield
stress with increasing hydrostatic pressure for all solute elements. The calculated pressure dependence is in
qualitative agreement with experiments, but underestimated quantitatively. It is suggested that the experimentally observed pressure dependence is caused by both the static and the transient dilatancy of dislocations. In
contrast to magnesium and copper atoms, silicon atoms are found to interact non-elastically with dislocations
within the core field, indicating that the favourable position for the silicon atoms is in the distorted sites in the
matrix.