Internal Stress Superplasticity in 2024 Al-SiC Whisker Reinforced Composites

Abstract
The isothermal and thermal cycling creep behavior of SiC whisker reinforced aluminum composites was investigated. Compression creep tests were performed for two volume fraction composites (10% SiC and 20% SiC), in both the longitudinal and transverse direc tions. The creep rates under thermal cycling conditions are much higher than under isothermal conditions due to the contribution of internal stresses. The aluminum matrix exhibits Newtonian flow behavior under thermal cycling conditions which results in rapid reorientation of the SiC whiskers. A creep relation is developed based on an internal- stress-plasticity model, which fits well with the thermal cycling creep data.