High Temperature Internal Friction in NiAl Single Crystals

High Temperature Internal Friction in NiAl Single Crystals

The internal friction of high-purity NiAl single crystals was investigated utilizing a low-frequency subresonance torsion a p m . Above lOOOK the damping increases strongly up to Q-' =0.3 at 1400K. The activation enthalpy of this viscoelastic relaxation depends on the composition and shows the highest value (2.8eV) for stoichiometric NiAl. The results are discussed in terms of diffusionantrolle...

Internal Friction Associated with High-temperature Dislocation Mobility

I n t e r n a l f r i c t i o n associated w i t h d i s l o c a t i o n mobil i t y can be c las s i f i e d i n t o th ree catagor ies: (1) Those o r i g i n a t e d from t h e i n t r i n s i c p roper t ies o f s i n g l e d is loca t ions ; (2 ) those o r i g i n a t e d from the i n t e r a c t i o n between d is. l o c a t i o n s and p o i n t defects; (3 ) those o r i g i n a t e d fro...

STUDY OF DISLOCATION - POINT DEFECTS INTERACTION IN MgO SINGLE CRYSTALS BY INTERNAL FRICTION

Irradiated Single Crystals for High Temperature Measurements in Space Applications

While spacecrafts experience temperatures from -120 to 110°C on the orbit, their surface reaches extremely high temperatures, well above 1000 °C, during descent into the atmosphere due to aerodynamic heating. Sophisticated insulation systems are designed for thermal protection. One of the steps in designing a protection system is experimental temperature measurements. Neutron flux induces point...

Amplitude-dependent Internal Friction and Dislocation Mobility in Crystals

The amplitude-dependent internal friction due to dislocations oscillating in the lattice is described in terms of dislocation mobility. This kind of intemal friction is expressed in elementary forms in the two limiting cases, i.e. at hish and low frequencies, and with the results obtained, the behavior of relaxation peaks due to dislocations are discussed 1 INTRODUCTION The amplitude-dependent ...