Studying the behaviour of the dislocation density and the loop length with the compressional deformation at room temperature in high purity polycrystalline aluminium

Abstract

The pulse echo technique was used to measure the ultrasonic attenuation in polycrystalline aluminium crystal having 5N purity. From the measured ultrasonic attenuation and velocity of sound in the metal with the use of the Granato-Lücke model, we were able to numerically find the behaviour of the dislocation density Λ and the dislocation loop length L with the compressional deformation ε The value of L was found to decrease from 0.7 × 10 −8 cm to 0.4 × 10 −8 cm as the deformation was increased up to 17%. On the contrary the value of Λ increased from 10 12 up to 10 13 cm −3. The results support the model. This conclusion was made after eliminating the extra attenuation resulting from bonding, diffraction and the non-parallelism effect.