Acoustoplastic effect and amplitude-dependent internal friction during deformation of impure aluminium single crystals

Time, temperature, plastic strain, strain rate and oscillatory stress amplitude dependences of the acoustoplastic effect and dislocation amplitude-dependent absorption of ultrasound causing this effect have been studied during three-point bending of aluminium single crystals. The acoustoplastic effect was observed not only during macroplastic deformation, but during microplastic deformation on ''elastic'' loading and during strain recovery on unloading as well. The time dependence of the acoustoplastic effect shows two components: ''fast'' (time-independent) and ''slow'' (time-dependent). Data obtained evidence for the distinction in defect structure levels responsible for the acoustoplastic effect and amplitude-dependent internal friction. Dislocation - dislocation interaction is suggested as a basic source of the acoustoplastic effect. Dislocation - point defect interaction plays a secondary part in mechanism of the acoustoplastic effect, even in case of dynamic strain ageing.