DISLOCATION MECHANISMS IN AL-RICH AL-LI ALLOYS

Thin foils of two binary delta'-strengthened Al-rich Al-Li alloys have been tensile tested inside a transmission electron microscope (TEM) a t temperatures ranging from 293 to 373 K. The volume fraction of the d elta'-precipitates was 0.047 and 0.099 and their average radius 6.7 an d 9.6 nm, respectively. These experiments yield information concerning the following points: (i) activated glide planes; (ii) dislocation co nfigurations (paired and unpaired dislocations); (iii) jerky motion; ( iv) planar slip and cross-slip; and (v) bowing out of the leading disl ocations in comparison to the trailing ones. These results are discuss ed with reference to those obtained for gamma'-hardened Ni-base supera lloys. (C) 1997 Elsevier Science S.A.