Phenomenon of reversion after ageing in magnesium alloys with gadolinium and samarium

The parameters of reversion after hardening ageing of magnesium alloys containing two rare-earth metals: gadolinium (yttrium group) and samarium (cerium group) were determined at various ratios of their contents. The reversion was observed at short annealing at 250 and 300 °С beginning with 5 minutes after preliminary ageing at 200 °С up to maximum hardening and consisted of significant softening of the alloys then. Measurements of the electrical resistance indicated, that during softening the reverse dissolution of the rare-earth metals in magnesium-base solid solution takes place with diminution of the hardening particles quantity, precipitated during ageing before The reverse dissolution of the rare-earth metals into solid magnesium increases with elevating annealing temperature after ageing from 250 to 300 °С and with increase of the gadolinium to samarium ratio in the alloys.