Investigation of the Elastic Behavior of Al-Li-X Alloys.

Abstract : Several A1 alloys were investigated. The Young's modulus, shear modulus and Poisson's ratio were determined using an ultrasonic pulse echo technique. The elastic properties were measured as a function of aging time, aging temperature, amount of stretching and testing direction. An increase in Young's modulus due to delta prime and T1 precipitation has been measured and treated quantitatively including precipitation kinetics. A significant decrease of about 5% in the modulus of elasticity can be found in peak age conditions. This decrease can be attributed to precipitation of the T2 phase. The shear modulus behaves similar to Young's modulus while the Poisson's ratio remains unchanged. There is no significant orientation dependence of the elastic properties on testing direction despite the fact that a typical rolling texture was present.