Abstract
Dependence of internal friction on temperature was measured by means of low frequency damped vibration for Al-0.8wt% Mg2Si, Al-0.62wt% Mg2Si-0.18wt% Si, and Al-0.54 wt% Mg2Si-0.26wt% Mg alloys aged at 150, 200, and 230°C.
The principal results obtained by experiments were as follows:
(1) The specimens aged had a peak of internal friction at a temperature of 90140°C. The peak would be due to the inner part of the precipitate body.
(2) The activation energy of the peak for a specimen aged at 150°C was 27, 00037, 000 cal/mol, which was nearly idential with that due to diffusion of Mg and Si in Al. When a specimen had been aged at higher temperature, its activation energy of the peak was increased with the rise of ageing temperature. The value of the energy of a specimen aged at 230°C was 42, 00058, 000 cal/mol, which was nearly identical with the atomic bond energy.
