I n t e r n a l f r i c t i o n and Young’s modulus changes over the range 10 t o
600i~n~ l a bor a tory c a s t samples of SONOSTON, a binary Mn-Cu a l l o y and
samples cut from a 200-kg propeller blade cast from SONOSTON are compared.
The high-damping s t a t e a t roan temperature i n SONOSTON is very amplitude
dependent, and the r e s u l t s a r e similar to those observed i n ferromagnetic
high-damping alloys. Besides the high-damping peak close to room temperat
u r e , there is a major relaxation peak i n SONOSTON and i n the binary fi/Cu
a l l o y a t * 400’~. The 400~pe~ak is probably a Zener-type r e l a x a t i o n
involving the stress-induced ordering of Mn atoms.