Creep deformation behavior and dislocation substructures of Mg–Y binary alloys

Compressive creep behavior and deformation substructures of binary Mg–Y alloys containing 0.2–2.4 mol% Y were investigated at 550–650 K under 4–200 MPa. The addition of yttrium improves creep strength of magnesium more efficiently than aluminum and manganese. This efficiency decreases with increasing temperature. The apparent activation energy for creep is substantially greater than that for self-diffusion in magnesium. Transmission electron microscopy revealed that the non-basal slip systems are activated at 650 K although the basal slip systems mainly operate at 550 K. Both the high activation energy and the cross-slip of dislocations from the basal to the non-basal planes can be explained consistently by the cross-slip mechanism.