Deformation and Fracture Behavior of Alumina Particle-Reinforced Al 6061-T6 Composite during Dynamic Mechanical Loading

Alumina particle-reinforced aluminum 6061-T6 composites are subjected to deformation at high strain rates in torsion and in compression using Hopkinson bars. The volume content of alumina particles in the aluminum alloy are 10 and 20 pct. While occurrence of adiabatic shear bands is evident under compression, the specimens fractured rapidly in torsion at high strain rates. Fracture occurs in both testing modes by ductile shear failure with elongated dimples originating mostly from the particle matrix interface. Most of the reinforcing particles along the crack propagation path fractured in torsion. However, excessive thermal softening inside the shear bands in the specimens under compression loading caused debonding rather than fragmentation of most particles as the crack propagates along the shear bands.