Elasticity, Anelasticity and Yield Strength of Al-Si Alloys Obtained by Directional Crystallization

摘要

Acoustic measurements of Young's modulus and internal friction at frequencies of longitudinal vibrations of about 100 kHz were made in the (5×10~(-7) to 2×10~(-4)) vibration strain amplitude range for Al-Si alloys. Quasi-static bending stress-strain diagrams were studied as well. The samples of the alloy were prepared using a directional crystallization by Stepanov's method. The compositions varied from 8 to 25 wt.%Si. The micro-plastic deformation of the materials (acoustic experiments) is explained by dislocation motion in grains of α solid solution. The microplastic yield stress has a minimum near the eutectic composition; the flow stress of plastic bending increases smoothly when the Si content increases.