Abstract
In the previous experiment on the isothermal aging of duralumin (17S), it was found out that there was an unstable stage particularly in its early stage, where the internal structure fluctuated much; the hardness the decrement of the Harbert pendulum, the specific volume, the lattice constant and the intensity of the Debye ring remarkably changed upto the saturated value and, especially, the damping capacity of the oscillation was very sensibly affected so that many peaks appeared, and that these fluctuations were most remarkable under the temperature of 150°C-180°C.
Under this experiment, 2S was tried to be used for finding out whether the appearance of many peaks are caused by 17S or by the error of measurement, and also for getting some aid for analysing the aging phenomena, particularly the internal change in the early stage of aging.
Although 2S has been seamed to be a non-aging metal at least from the viewpoint of hardness curve, the result of the decrement of oscillation, the specific volume analysis and X-ray analysis shows there are considerable changes by aging. Especially, in early stage of aging, th changes of the damping capacity of torsional oscillation are very unstable and several peaks appear. It is thus found out that the aspect of the changes is similar to that in 17S's case, though they are in less degree. It can be said, therefore, that the big fluctuation of damping capacity in early of the aging of 17S is not dependent upon the complexity of the composition but upon such internal defects in material as dislocation.
