Elasticity, anelasticity, and microplasticity of directionally crystallized aluminum–germanium alloys

The structure, Young's modulus defect, and internal friction in aluminum-germanium alloys have been studied under conditions of longitudinal elastic vibrations with a strain amplitude in the range of 10$^{-6}$ – 3 $\times$ 10$^{-4}$ at frequencies about 100 kHz. The ribbon-shaped samples of the alloys with the germanium content from 35 to 64 wt% have been produced by drawing from the melt by the Stepanov method at a rate of 0.1 mm/s. It has been shown that the dependences of the Young’s modulus defect, logarithmic decrement, and vibration stress amplitude on the germanium content in the alloy at a constant strain amplitude have an extremum at 53 wt% Ge. This composition corresponds to the eutectic composition. The dependences of the Young’s modulus defect, the decrement, and vibration stress amplitude at a constant microstrain amplitude have been explained by the vibrational displacements of dislocations, which depend on the alloy structure.