Changes in the microstructure of magnesium composites estimated by non-destructive methods

The microstructure of magnesium composites is influenced by thermomechanical treatments. The effect of thermal cycling on the damping behaviour, acoustic emission and thermal properties of composites with AZ91 magnesium alloy reinforced with Saffil short fibres was investigated. The values of the logarithmic decrement in the strain amplitude dependent region depend very sensitively on the upper temperature of cycles. Thermal cycling and/or changes in temperature may cause changes in the density of dislocations. The density of the newly created dislocation depends on the reinforcement volume fraction, the reinforcement shapes and the difference in the coefficients of thermal expansion of both of the composite components. The microstructure changes of magnesium composites due to thermal cycling are estimated using non-destructive methods such as internal friction measurement after thermal cycling, dilatometry and acoustic emission during thermal cycling and thermal properties.