Internal Friction in Aluminum at Low Temperatures

Preliminary measurements at 40 kc of the internal friction of 99.992% aluminum as a function of temperature yield a number of attenuation maxima at temperatures between 90°K and 300°K. These maxima are unlike the cold-worked induced peaks, first reported by Bordoni. They appear to be of two types, a broad maximum at about 225°K and a series of very sharp peaks at lower temperatures. The latter are tentatively associated with the break away of dislocations from minor pinning points.