ANISOTROPY OF ELASTIC PROPERTIES IN VARIOUS ALUMINUM-LITHIUM SHEET ALLOYS

Anisotropic elastic properties of recrystallized and unrecystallized A l-Li sheets have been experimentally studied and compared with theoret ically predicted results. A conventional AA2024 alloy in the annealed condition as a reference material has also been investigated. A concep t of lithium equivalent has been proposed in order to calculate single crystal elastic constants C-11, C-12 and C-44 for commercial Al sheet alloys. Subsequently, these calculated single crystal elastic constan ts were applied to predict the Young's modulus, using Bunge's method w ith quantitative texture data which were determined by X-ray and neutr on diffraction techniques. To calculate the shear modulus the Bunge's method was extended. It is shown that elastic properties of the alloys can be essentially predicted on the basis of Bunge's method with calc ulated single crystals C-ij. The measurement results of the Young's mo dulus and shear modulus of polycrystalline Al-Li alloys were carried o ut using a dynamic resonance method. They were found to be in fair agr eement with calculated curves using the neutron texture data with the calculated single crystal elastic constants C-ij. The results showed t hat elastic properties depend strongly on testing direction due to the crystallographic texture and grain shape. The texture gradients also strongly affected the elastic properties of Al-Li alloys, but only sli ghtly affected those of the conventional 2024 Al alloy. A slight stret ch reduces the modulus of Al-Li by a small amount.