Thermal stresses in Mg–Ag–Nd alloy reinforced by short Saffil fibers studied by internal friction

Mechanical spectroscopy has been used in order to investigate thermal stresses relaxation in the QE22 magnesium alloy (Mg–2Ag–2Nd) reinforced with 20 vol.% of δ-alumina short fibers (Saffil® fibers). Composite has been processed by a squeeze cast technique. Specimens have undergone thermal cycling between 20 and 450 °C with different temperature rate T ˙ and excitation frequency ω. The relaxation of thermal stresses gives rise to additional internal friction. The mechanical loss versus temperature spectrum showed a transient maximum while heating and two maxima while cooling. A model where thermal stresses are relaxed by dislocation motion controlled by a solid friction mechanism has been used to interpret the experimental results.