ABSTRACT
M g - 1 1 . 5 mass % Y show the quite complicated nature of the hardening effect during solid
solution decomposition in M g alloys with rare earth metals and its dependence on the
ageing temperature.
It is natural to suppose that the regular acceleration of the hardening effect decrease
with rising ageing temperature in the order of the atomic number increase established for
G d , Tb, D y continues in the next rare earth metals of the lanthanum series. To a certain
extent, experiments with M g - Y confirm even this supposition. Nevertheless, there is not
enough assurance that it is so. Moreover, some experiments on the M g - E r and M g - L u
alloys show the existence of a significant hardening effect in them after ageing at 250 and
300°C [106, 273] contradicting the established tendency for G d , Tb, D y . It is possible that
at one of the elements of the yttrium subgroup after D y the established temperature depend-
ence of the hardening effect during ageing on the rare earth atomic number changes into an
opposite one. A number of additional experiments are required to answer this question.
