Abstract
Internal friction of Mg-Sc alloys has been studied after sequential thermal treating. The obtained strain amplitude dependences of the logarithmic decrement can be divided into two regions. In the region of small strain amplitudes the decrement is dependent on the amplitude only slightly while at higher amplitudes the decrement depends strongly on the amplitude. Both regions are separated by a critical strain amplitude. The thermal treatment of alloys changes the sample microstructure. These changes are reflected in the dependence of the critical amplitude on the thermal treatment temperature. An increase of the critical amplitude with temperature up to 160 °C is interpreted on the base of the theory of vibration of short and long dislocation segments caused by a sonic wave. Solving of Sc clusters (up to ~160 °C) is very probably followed at higher temperatures by a precipitation process.

Key words
Mg-Sc alloys, internal friction, precipitation, homogenisation, dislocations

Full text not available