ACOUSTOPLASTIC EFFECT AND AMPLITUDE-DEPENDENT INTERNAL-FRICTION DURING DEFORMATION OF IMPURE ALUMINUM SINGLE-CRYSTALS

Time, temperature, plastic strain, strain rate and oscillatory stress amplitude dependences of the acoustoplastic effect and dislocation amp litude-dependent absorption of ultrasound causing this effect have bee n studied during three-point bending of aluminium single crystals. The acoustoplastic effect was observed not only during macroplastic defor mation, but during microplastic deformation on ''elastic'' loading and during strain recovery on unloading as well. The time dependence of t he acoustoplastic effect shows two components: ''fast'' (time-independ ent) and ''slow'' (time-dependent). Data obtained evidence for the dis tinction in defect structure levels responsible for the acoustoplastic effect and amplitude-dependent internal friction. Dislocation - dislo cation interaction is suggested as a basic source of the acoustoplasti c effect. Dislocation - point defect interaction plays a secondary par t in mechanism of the acoustoplastic effect, even in case of dynamic s train ageing.