Structural State Stability of Superlightweight MA21 Magnesium-lithium Alloy.

The instability of the structural state and mechanical properties of MA21 alloy occurring after prolonged storage or at high temperatures is caused mainly by a transition of the metastable theta phase to the equilibrium AlLi phase, and also by the dissolution and coagulation of dispersed hardening phases (MgLi//2Al and AlLi). To obtain an optimal combination of properties, heating of MA21 alloy prior to quenching and deformation should be carried out at temperatures no lower than 350 degree C, while the maximum temperature of subsequent agings or process heatings should not exceed 100 degree C with the minimum possible holding (1 to 3 hours).