Abstract
The thermal expansion characteristics of magnesium alloy AS21 reinforced with 25 vol.% of Saffil^® short fibres were measured in the temperature range from room temperature to 380°C. The same measurements were also performed for samples pre-strained in tension as well as in compression. Permanent sample length changes (elongation as well as contraction) were found after the first thermal cycle. The microstructure of samples was examined by transmission electron microscopy (TEM). Stress relaxation tests were used to estimate the internal stress in the alloy as well as in the composite. Residual thermal stresses and different plastic deformation mechanisms in tension as well as in compression are responsible for the thermal expansion behaviour.

Key words
magnesium alloy based composite, thermal stresses, plastic deformation, dislocations, twinning

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