W. Hermann et al., INTERNAL-FRICTION IN NICKEL-BASE SUPERALLOYS IN THE KHZ-RANGE AT TEMPERATURES BETWEEN 20-DEGREES-C AND 1250-DEGREES-C, Journal de physique. IV, 6(C8), 1996, pp. 223-226
Damping measurements were carried out on two-phase (gamma-matrix, gamm
a'-precipitates) nickel-base alloys containing different volume fracti
ons of gamma' in order to achieve a better understanding of the strong
elastic modus decrease between 1000 degrees C and 1100 degrees C. For
the investigation of the damping a free-fi ee beam flexural vibration
technique was applied. Nickel-base alloys with a high volume fraction
of gamma', like CMSX-4, and the intermetallic phase Ni3Al, the near g
amma'-phase, show two different damping peaks between 1000 degrees C a
nd 1200 degrees C. The measurements on alloys with a low volume fracti
on of the gamma'-phase and of a near-gamma matrix material lead to onl
y one damping maximum in this high-temperature range. A comparison of
the evaluated damping parameters leads to the assumption that the diff
usion of nickel and aluminium atoms in the gamma'-phase most probably
is responsible for the relaxation processes in nickel-base alloys such
as CMSX-4.