Strain-rate Sensitivity of Aluminum 2024-T6/TiB2 Composites and Aluminum 2024-T6

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 Ti B2 particles, respectively. These micro-cracks can accelerate the brittle fracture of the composites. The aluminum 2024-T6/Ti B2 composites showed various fracture characteristics and shear instability was the predominant failure mechanism under dynamic loading.