Ductility of cold-rolled and recrystallized Ni_3Al foils

摘要

The room-temperature ductility of 95 percent cold-rolled and recrystallized Ni_3Al (Ni-24.0 at.percent Al) foils was examined as a function of heat-treatment conditions. The cold-rolled, diffused Goss texture changed to a complicated, transitional texture in the early stage of grain growth and then returned to a similar diffused Goss texture in the late stage. With the texture evolution, the total area fraction of the tough grain boundaries (GBs) such as SIGMA 1, SIGMA 3, and SIGMA 9 increased from 0.23-0.38 in the early stage to 0.56-0.73 in the late stage. Tensile and bending tests revealed that the ductility was drastically improved with the grain growth. The foils in the early stage fractured without showing yielding. In contrast, the foils in the late stage were very ductile, and the tensile elongation increased to 10 percent with the grain growth. It was confirmed that there was no in-plane anisotropy in ductility. The ductility improvement with the grain growth was ascribed to the increase in the area fraction of the tough GBs.