LIV. Density changes during the annealing of deformed nickel

A differential method has been used to measure the changes in density which accompany the annealing of plastically deformed nickel. The results of these measurements are correlated with earlier measurements of stored energy, electrical resistivity and hardness for the same material. There are two sudden increments in density; the first is attributed to the disappearance of vacancies and the second to recrystallization. These are superimposed on a gradual increase in density attributed to recovery. There is a considerable discrepancy between the densities of dislocations calculated from the stored energy measurements and from the density measurements.