The features of the microstructure of quenched Al-Li alloys with lithium co
ncentration below the solubility limit (3.8 at. %) and above the solubility
limit (7.0 and 10.4 at. %) are studied by the x-ray diffractometry. In add
ition to the standard structural reflections, the diffraction patterns of a
ll the alloys show diffuse halos that fall off in intensity as the lithium
concentration is increased. As a result of an analysis of the intensity of
the diffuse scattering of x rays it is established that the observed halos
are due to short-range order of the layered type in regions with a characte
ristic radius of 1.5 nm. The decrease in the intensity of the diffuse halo
on the diffraction pattern of the alloy Al-10.4 at. %Li and the appearance
of new structural reflections are explained by the precipitation of dispers
e particles of the delta' phase. It is shown that these particles have a su
bstantial influence on the mechanism of plastic deformation in these alloys
in the temperature region 40-170 K. (C) 2000 American Institute of Physics
. [S1063-777X(00)01507-3].