Dynamic mechanical properties and failure mechanism of 50vol%SiCp/2024Al composites

Abstract
SiCp/2024Al metal matrix composites with a 50% volume fraction of SiC particle were fabricated by squeeze casting. SiCp/Al composites are good armor material candidates due to its low density, high strength density ratio, mid-toughness, and the mechanical properties and the underlying failure mechanism under shock loading are very important for armor material. In this paper, the compressive strength and strain rate effect of the composite under shock loading were examined by Split Hopkinson Pressure Bar, and failure mechanism was investigated. The experimental results showed that the dynamic flow stresses of the 50vol%SiCp/2024Al metal matrix composites are higher than those under quasi-static loading condition. And the flow stresses of the composites decrease with strain rates increasing from 2100 to 6000/s. Combining the results of literature on MMCs with 50vol% particle content, the present results indicated that the critical strain rate, under which the dynamic behavior would change from strain rate strengthening to strain rate softening, is about 2100/s. Main failure modes under high strain rate are adiabatic shear failure; inside the shear bands the reinforcement particles are denser and finer. There are distinct adiabatic shear bands in loaded composites when the strain rate up to 6000/s.