Dependence of Elastic Modulus on Microstructure in 2090-type Alloys

The Young's modulus, s h e a r modulus and P o i s s o n ' s r a t i o were d e t e r m i n e d u s i n g a n u l t r a s o n i c p u l s e e c h o t e c h n i q u e . T h r e e c o m m e r c i a l l y f a b r i c a t e d a l u m i n u m c o p p e r l i t h i u m a l l o y s and an aluminum-lithium binary a l l o y were examined. The e l a s t i c p rope r t i e s were measured a s a func t ion of aging time, aging temperature, amount of s t r e t c h i n g and t e s t i n g d i rec t ion . An inc rease i n Young's modulus due t o d e l t a prime and T1 p r e c i p i t a t i o n has been measured and t r e a t e d q u a n t i t a t i v e l y i n c l u d i n g p r e c i p i t a t i o n k i n e t i c s . A s i g n i f i c a n t d e c r e a s e of a b o u t 5% i n t h e modulus of e l a s t i c i t y was found i n t h e peak age condit ion. This decrease can be a t t r i b u t e d t o p r e c i p i t a t i o n of t h e T2 phase. The shear modulus behaves s i m i l a r t o Young's modulus whi le t h e Poisson's r a t i o remains unchanged. There is no s i g n i f i c a n t o r i e n t a t i o n dependence of t he e l a s t i c p r o p e r t i e s on t e s t i n g d i r e c t i o n d e s p i t e t he f a c t t h a t a typ ica l . r o l l i n g t e x t u r e was present.