Abstract: The low-temperature tensile and notched tensile properties of rapidly solidified Al-4.74Cu-1.30Li-0.38Mg-0.42Ag-0.21Zr alloy have been studied with tests camed out from room temperature down to 77K. The fractography is examined by means of scanning electron microscopy(SEM) while transmission electron microscopy is employed to study the microstructure and dislocation mopohologies.It is discovered that the allov shows a linear in-crease in strength and a gain in deformation hardening capability when temperature is lowered while the change ofelongation-to-fracture differs with different aging states. The alloy displays much better notch perfonnance than conventional aluminum alloys at 77K regardless of the de-crease in notch-strength with drop in temperature.The change of dislocation morphologies is found to play an important role in the improvement of strength and ductility at low temperatures.

Key words: aluminum-litbium alloys, lowtemperature tests, notch sensitivity