The deformability of wrought magnesium alloys at room temperature is limited and a way to overcome this limit is to carry out forming operations in warm or hot conditions. In the case of fine grained alloys, superplastic properties can be generally achieved but in this regime, the Mg alloys are sensitive to strain induced cavitation. However, large grained alloys can also exhibit quite large deformabilities when they are deformed at high temperature. It is due to the fact on the one hand, that Mg alloys can quite easily recrystallise dynamically and on the other hand that dislocation movements can be controlled by a solute drag effect leading to significant strain rate sensitivity parameters. These various mechanisms of deformation can be obtained depending mainly on the composition, the mean grain size and the conditions of deformation (i.e. temperature and strain rate). In this presentation, the high temperature deformation mechanisms as well as the associated damage mechanisms of various wrought magnesium alloys will be discussed.
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