Abstract
The dynamic deformation behaviour of aluminium single crystals (99.99% purity) was investigated by compression tests at room temperature using a bar-bar type impulsive loading apparatus. The dynamic stress-strain relation at strain rates of the order of 102 sec−1 shows a similar orientation dependence to the static one. Crystals properly oriented for single slip under dynamic deformation show higher critical resolved shear stresses and more extensive easy glide regions than those under static deformation. The values of the critical resolved shear stresses for dynamic deformation range from 250 g/mm2 to 500 g/mm2. The rate of work hardening of stage II is shown to be higher for the dynamic deformation than for the static one. Microscopic observations on slip markings reveal that the dynamically deformed specimens have slip bands which are higher in density and weaker in contrast than the statically deformed ones.
On the basis of the above results, it is pointed out that for the easy glide region of deformation at high strain rates the frictional stress acting on moving dislocations becomes too large to be negligible and contributes greatly to the critical resolved shear stress and the flow stress.
