High Temperature Flow Behavior and Microstructure of Al-Cu/Mg2Si Metal Matrix Composite

The present work deals with the high temperature flow behavior and the microstructure of the Al-Cu/Mg2Si metal matrix composite. Toward this end, a set of hot compression tests was performed in a wide range of temperature (573-773 K) and strain rate (0.001-0.1 s(-1)). The results indicated that the temperature and strain rate have a significant effect on the flow softening and hardening behavior of the material. The work hardening rate may be offset due to the occurrence of the restoration processes, the dynamic coarsening, and spheroidization of the second phase particles. In this regard, two phenomenological constitutive models, Johnson-Cook (JC) and Arrhenius-type equations, were employed to describe the high temperature deformation behavior of the composite. The JC equation diverged from experimental curves mainly in conditions which are far from its reference temperature and reference strain rate. This was justified considering the fact that JC model considers thermal softening, strain rate hardening, and strain hardening as three independent phenomena. In contrast, the Arrhenius-type model was more accurate in modeling of the flow behavior in wide range of temperature and strain rate. The minor deviation at some specified conditions was attributed to the negative strain rate sensitivity of the alloys at low temperature deformation regime.