Dislocation mechanisms in Al-rich Al-Li alloys

Thin foils of two binary δ′-strengthened Al-rich Al-Li alloys have been tensile tested inside a transmission electron microscope (TEM) at temperatures ranging from 293 to 373 K. The volume fraction of the δ′-precipitates was 0.047 and 0.099 and their average radius 6.7 and 9.6 nm, respectively. These experiments yield information concerning the following points: (i) activated glide planes; (ii) dislocation configurations (paired and unpaired dislocations); (iii) jerky motion; (iv) planar slip and cross-slip; and (v) bowing out of the leading dislocations in comparison to the trailing ones. These results are discussed with reference to those obtained for γ′-hardened Ni-base superalloys.