EXPERIMENTAL STUDY ON DYNAMIC COMPRESSION PROPERTIES OF SiCp/2024Al PARTICLES-REINFOCED METAL MATRIX COMPOSITES

The dynamic compression tests of SiCp/2024Al metal matrix composites with the 50% fraction of particles were performed by Split Hopkinson Pressure Bar(SHPB. Dynamic stress-strain curves at the strain rates ranging from 1250/s to 2500/s were obtained, compared to the quasi-static results. Based on the SHPB hypothesis, pulse shaping technique was employed to maintain the specimen in the equilibrium and uniform deformation state over the testing course. The results showed that the flow stress and plastic strain of the composite considerably increased at high strain rates compared with the quasi-static results. The composites showed obvious strain-rate sensitivity. And the failure modes were brittle fracture. The fracturing surfaces were characterized by a scanning electron microscopy. It was obvious that the matrix was softened/melted by heat generated during adiabatic compression. The effects of strain rates and particle fraction on the failure mode and deformation mechanism were also discussed.