The Microstructure and Deformation Behavior of Al-Fe-Mn Alloys with Different Fe Contents during Cold Rolling

The microstructure transformations and deformation behavior of Al-Fe-Mn alloys with different Fe contents during their cold rolling process were investigated by means of hardness testing, conductivity testing, and transmission electron microscopy. It was observed that the hardness of the two alloys increased initially along with the levels of cold rolling reduction, then reduced when levels of cold rolling reduction increased further. Two kinds of deformation behaviors, work hardening and work softening, were observed during cold rolling for both Al-Fe-Mn alloys with different Fe contents. The critical level of cold rolling reduction that led to the change from work hardening to work softening was different in both alloys and the critical level of cold rolling reduction of the alloy with high Fe content was significantly lower than that of the alloy with low Fe content. During the work hardening process, the number of dislocations in the alloys increased continuously as the level of cold rolling reduction increased and they were accompanied by the formation of substructures. After the occurrence of work softening, the dislocation density in the alloys was significantly reduced. The sub-grain structures polygonized and ultimately transformed into equiaxed sub-grains.