| The thermal cycling and creep resistance of metal matrix composites (MMCs) was studied both experimentally and analytically. The thermal cycling creep test of SiC particulate/A359 Al composites was performed by a creep/thermal cycler with a constant stress cam, by which the specimen is always loaded under a constant stress condition. Two typical temperature profiles were used for the thermal cycling of the specimen, each with maximum temperatures of 300 and 350A new dislocation punching model for MMCs reinforced with prolate particulates was proposed by using simultaneous punching of dislocation loops in both longitudinal and transverse directions. The stress fields before and after relaxation and the punching distance were computed by the Eshelby theory coupled with the mean field approach, and their results were compared to other models and experimental results from the literature. This model results in a shorter punching distance than other models, giving good agreement with the experimental results. The strengthening of the metal matrix due to the dislocation punching was also computed and gave results which compared reasonably well with other models.An analytical model for thermal cycling and creep resistance for prolate particulate reinforced MMCs was developed by using the aforementioned dislocation punching model. This model simulates elastic fibers and an elastic-plastic-creeping matrix obeying the creep equation of power-law type. It predicts a dimensional change per thermal cycle by considering the combined effects of the thermal residual stress, applied stress and stresses due to bulk creep and diffusional strain at the particulate-matrix interface. The average internal stress in the matrix is calculated at each temperature of a temperature profile by using the temperature-dependent yield stress of the matrix and the dislocation punching model. The predicted results using the material properties of each constituent and temperature profile as input data were in good agreement with the experimental results. A parametric study was also conducted in terms of a fiber volume fraction, a fiber aspect ratio and temperature profiles. |
