Influence of Strain Rate and Temperature on the Compressive Deformation of a Eutectic Al-Si Alloy Based Composite Reinforced with -Si_3N_4 Whisker

摘要

The compressive properties characterized as a function of the true stress-strain response of a-Si_3N_4 whisker reinforced 4032 aluminum alloy composite were examined at strain rates ranging from 10~(-3) to 10~0 s~(-1) in the temperature interval 500 approx 620 deg C. The effect of compressive deformation parameters such as strain rate and temperature on the mechanical behavior was systematically investigated. The strain rate sensitivity exponent and activation energy were calculated. The activation energy is 126 KJmol~(-1) at 500 deg C to 540 deg C, close to that for lattice self-diffusion in aluminum (142KJmor'), and is 210 Klmol~(-1) at 540 deg C to 580 deg C (epsilon=0.37s~(-1)). The compressive deformation behavior of the composite can be described quantified by the Zener-Hollomon parameters (Z) for the solid state and the Non Newton-fluid for the semi-solid state of the composite. It is demonstrated that a linear equation of the logarithmic Z fits the flow stress of the composite at elevated temperatures. The compressive deformation mechanisms of the ct-Si3N4W/4032Al composite were discussed preliminarily.