Effect of Temperature Change on Behaviour of Lattice Defects During Low-Cycle Fatigue

Torsional fatigue tests were carried out on commerical Al wires by changing the temperature from 77K to room temperature (R T) or vice versa , and resistivity was measured as a function of the number of cycles at 77K. After the temperature change from RT to 77K, the resistivity increased with the number of cycles, and saturated at an advanced stage of fatigue. This phenomenon was explained from the change in lattice defect density in terms of the dislocation density prior to the temperature change, the concentration of point defects, and the cumalative strain after the temperature change. The decrease in resistivity induced during fatigue after the temperature change from 77K to RT was thought to occur mainly due to dynamic annealing of point defects. 14 ref.--AA