In order to clarify the deformation and fracture mechanisms of Al-Li alloy the tensile behaviours of binary Al-Li polycrystals and single crystals have been studied at different aged conditions and different experiment temperature in this paper. The fatigue behaviours also have been studied on Al-Li single crystals at ambient temperature. The slip mechanisms of dislocation, Fracture style and occurance of shear localization have been analyzed in the present study. The experiment data are shown that binary Al-Li polycrystals have not always good strnegth at lower temperature. The increment of elongation is followed by the raise of (σ_b-σ_s). In tensile process, P-L effection is always existed in every aged materials. The Fracture style changes from intergranular fracture to shear Fracture at 150K, when experiment temperature rise from 77K to 290K. In the experiment of fatigue in Al-Li single crystals, planar slip line has been found in peak-aged condition, but appears wave slip in over-aged condition. Saturation stress amplitude is very depondent on plastic strain amplitude at the range of 6.0 * 10~(-4) < δ_P < 4.0 * 10~(-3). It is shown that the interaction between dislocation and δ' precipitate phase particle, which has LI_2 style structure, is the major reason for different characters at different aged condition and temperature. The grain boundary has obvious influence on the strength and fracture style. The planar slip is not the directive reason for lower toughness on this mateiral. The strength of binary Al-Li alloy is dependent on boudnary, δ' particles and matrix.
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