High-temperature microstructural evolution and room-temperature mechanical properties of friction-stir-processed 5083 aluminum alloy

This work investigated the microstructural evolution occurring during high-temperature tensile tests (743 K, strain rate 1×10^-3 s^-1) of a friction stir processed polycrystalline solid solution 5083 aluminum alloy, along with the effect of the microstructure change on the room-temperature mechanical properties. Grain refinement was effectively achieved in the stir zone, with the mean observed grain size less than 10 μm. The nominal stress-nominal strain curve indicated that the flow stress drastically increased until a maximum stress value at which point fracture occurred. The value of elongation to failure exceeded 300%; this high ductility can be referred to as superplastic-like elongation. The area fraction of cavity increased with increasing strain. Room-temperature tensile tests at a strain rate of 1×10^-3 s^-1 revealed that the strength and ductility decreased with an increasing area fraction of cavity, and that the extent to which the strength and ductility are affected depends on the cavity.