Effect of Creep on the Microstructure of Aluminum Alloy AD1 in Recrystallized and Ultrafine-Grained States

The changes in the microstructure of industrial aluminum alloy AD1 in recrystallized and ultrafine-grained (UFG) states are studied before and after creep tensile tests at 0.3T_melt (100°C). It is established that, in the recrystallized structure, creep leads to the fragmentation of large elongated grains into smaller grains and subgrains, accompanied by an increase in the fraction of low-angle boundaries. In the UFG structure, grain growth (collecting recrystallization) is observed during the creep. A strong radial texture is identified, where the crystalline lattices of the alloy grains are predominantly oriented along the [001] crystallographic direction parallel to the axis of the original round rod (parallel to the rolling direction). This texture is typical of both recrystallized and ultrafine-grained samples. After creep tests, the UFG samples exhibit a shift in direction of the texture axis from [001] to [011]. This is accompanied by formation of particles of the secondary phase—aluminum carbide and silicon compounds—which is confirmed through CALPHAD phase diagram calculations. The dislocation structure of aluminum alloy AD1 is explored.