Strain-rate sensitivity of aluminum 2024-T6/TiB₂ composites and aluminum 2024-T6

Abstract

Strain-rate sensitivities of 55vol%–65vol% aluminum 2024-T6/TiB₂ composites and the corresponding aluminum 2024-T6 matrix were investigated using split Hopkinson pressure bar method. The experimental results showed that 55vol%–65vol% aluminum 2024-T6/TiB₂ composites exhibited significant strain-rate sensitivities, which were three times higher than the strain-rate sensitivity of the aluminum 2024-T6 matrix. The strain-rate sensitivity of the aluminum 2024-T6 matrix composites rose obviously with increasing reinforcement content (up to 60%), which agreed with that from the previous researches. But it decreased as the ceramic reinforcement content reached 65%. After high strain rates compression, a large number of dislocations and micro-cracks were found inside the matrix and the TiB₂ particles, respectively. These micro-cracks can accelerate the brittle fracture of the composites. The aluminum 2024-T6/TiB₂ composites showed various fracture characteristics and shear instability was the predominant failure mechanism under dynamic loading.

Keywords

composite materials / mechanical properties / dynamic compression / strain-rate sensitivity

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