A comparison between 2017A and 4047A aluminum alloys microstructure changes under thermal fatigue loading

This paper presents a study of 2017A and 4047A aluminum alloys microstructure changes under thermal fatigue loading. Specimens were subjected to a cyclic thermal load. The thermal fatigue loading is ensured by applying repetitive heating and cooling cycles; with a temperature variation between 80 and 280 degrees C using a lab made bench test. Only thermal loading was considered. No mechanical stress was applied during all tests. Change in mechanical properties of the tested materials was studied through hardness measurements, SEMmicrographic observations and XRD analysis for different cycle numbers. For the two alloys, the results showed that the hardness decreases when the cycle number increases. This observed phenomenon is more important in the case of 2017A alloy. Micrographic observation and XRD analysis led to conclude that this hardness decrease is due to the dispersion and morphology changes of the hardening precipitates, for the 2017A alloy, and silicon particles dissolution in case of the 4047A alloy.