Specific features of microstructure and low-temperature yield strength of quenched Al-Li alloys

The specific features of quenched Al-Li alloys microstructure with a Li content below the solubility point (3.8 at.%O) and above (7.0 and 10.4 at.%) are studied by the structure x-radiography technique. The diffraction patterns for all the alloys display the diffuse halos alongside the structure reflexes. The intensity of the halos decreases with increasing lithium concentration. The analysis of the x-ray diffuse scattering shows that the halos observed are due to the short-range order of the stratification type in the areas with a typical radius od 1.5 nm. The reduction diffuse halo intensity at the diffraction pattern from the Al-10.4 at. % Li alloy and the existence of new structure reflexes are associated with the release of δ-phase disperse particles. It is shown that it is just these particles effect essentially the mechanism of plastic flow of the alloys in the 40-170 K temperature range