Work-Hardening and Recovery Rates in Pure Aluminum Single Crystals during High-Temperature Deformation

In order to clarify the contribution of grain boundary effect on the work-hardening rate without recovery effect, h, and the recovery rate without work-hardening effect, r, these two parameters in pure aluminum single crystals have been measured and compared with those in aluminum polycrystals reported so far. The measurement has been carried out by applying the strain-rate change technique to the steady-state tensile deformation at temperatures from 523 K to 673 K and at shear strain rates from 1.2×10−5 s−1 to 4.6×10−4 s−1.It is found that h is approximately proportional to the inverse of stress and depends strongly on temperature. The stress exponent of r is about 3. The activation energy of r is about 2/3 of the activation energy of lattice self-diffusion in Al. These stress and temperature dependences of h and r are almost the same as those of the polycrystals.Therefore, it is concluded that the contribution of grain boundary effect to h and r is not large.