Aging-Induced Recovery of Magnesium Alloys with Various Rare-Earth Metals

Abstract

The aging-induced recovery of binary magnesium alloys with various rare-earth metals (Y, Nd, Sm, Gd, Tb, Dy, Ho), in which the decomposition of the supersaturated magnesium solid solution is accompanied by substantial hardening, is studied. It is found that annealing of the alloys at 250°C, which were preliminary aged at 200°C to a peak hardness, leads to their softening; in this case, the hardness continues to decrease as the annealing time increases. Electrical resistivity measurements show that, as a result of annealing at 250°C, recovery takes place and is accompanied by partial dissolution of the decomposition products in the magnesium solid solution; after that, its decomposition continues. The degree of recovery in the alloys with yttrium-group rare-earth metals (Y, Gd, Tb, and Ho) is found to be higher than that for the alloys with cerium-group rare-earth metals (Nd and Sm); within the lanthanide series, the degree of recovery increases with the atomic number of a rare-earth metal.