Deformation Behaviour and Microstructure of a 20% Al2O3 Reinforced 6061 Al Composite

Deformation and microstructural behaviours of a 20% (volumepercent) particle reinforced 6061 Al matrix composite have been studied bytorsion from 25 to 540°C with strain rates of 0.1, 1 and5 s^-1. The logarithmic stress versus reciprocal temperaturerelationship exhibits two slopes indicating different deformationmechanisms. The 20% Al₂O₃/6061 Alcomposite shows a greater hardening behaviour than those of the 10% Al₂O₃/6061 Al composite and of the monolithic alloy. Above 250°C, TEM investigations reveal muchsmaller subgrain size and higher volume of non-cellular substructures, aswell as dynamic recrystallization nuclei in the 20% Al₂O₃/6061 Al composite in comparison to those of the10% Al₂O₃/6061 Al composite and matrixalloy the same test condition. The torsion fracture surface was studied andcompared to the three point bending failure specimens.