Influence of Ni Content on Internal Friction and Acoustoplastic Effect in Cu-Ni Single Crystals

Abstract
Influence of Ni content in a range 1.3 - 7.6 at.% on amplitude-dependent internal friction and Young's modulus defect of Cu-Ni single crystals oriented for single slip has been studied by composite oscillator technique at frequencies of about 100 kHz in a wide strain amplitude range before, during, and after plastic deformation. The acoustoplastic effect was registered simultaneously with in situ internal friction measurements. Effects of the composition and temperature ranging from 6 to 255 K on damping and anelastic strain was studied and allowed to suggest multicomponent strain amplitude-temperature spectra of the amplitude dependent internal friction. A functional form of the amplitude dependence of the internal friction and Young's modulus defect is discussed. Data on in situ measurements allow to associate the amplitude-dependent internal friction and acoustoplastic effect with different mechanisms : dislocation - point obstacle and dislocation - dislocation interactions, respectively.