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Thermal Fatigue of AX41 Magnesium Alloy Based Composite Studied Using Thermal Expansivity Measurements



Magnesium alloy AX41 (Mg-4Al-1Ca in wt. %) reinforced with 15 vol% of short Saffil fibres was used in this study. Thermal expansion was measured over a wide temperature range from 25 up to 400 °C in four runs. The thermal expansion coefficient was estimated during heating and cooling. The Young’s modulus of the composite was estimated by the measurements of the resonant frequency of the free vibrations of the sample. Samples for these measurements were thermally cycled between room temperature and an increasing upper temperature of the thermal cycle. The modulus defect estimated from the difference between the resonant frequency before the thermal cycling and after cycling was compared with the relative change of the thermal expansion coefficient. Similar course of the temperature dependence of both quantities indicates that the deviation from the linearity has the common reason: thermal stresses and increased dislocation density.

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