LOW CYCLE FATIGUE OF BINARY Al-Li ALLOYS. II-MICROSTRUCTURAL CHARACTERIZATION AND IN SITU FATIGUE EXPERIMENTS

摘要

The fatigue behaviour of AlLi binary alloys is investigated at the microscopic scale using T.E.M., STEM, and in situ fatigue in T.E.M. on specimens previously fatigued in torsion. In the Al0.7%Li solid solution, a cell structure is observed. The Al2.5%Li alloy with small precipitates exhibit precipitate free bands which reflect a strong localization. The Al2,5%Li alloys with large precipitates show Orowan by passing but also shearing by the Orowan Loops. The three types of mechanisms were observed also by in situ straining experiments in the T.E.M.