Study on cryorolled Al-Cu alloy using X-ray diffraction line profile analysis and evaluation of strengthening mechanisms

Al-Cu alloy sheets were rolled at room temperature and at liquid nitrogen temperature to true strain values of 0.69 and 1.38. The microstructural changes and variation in mechanical properties due to the effect of rolling temperature was evaluated. X-ray diffraction line profile analysis was performed to calculate crystallite size, microstrain and dislocation density. Irrespective of the amount of reduction, cryorolled samples exhibited reduced crystallite size along with enhanced lattice strain and dislocation density than room temperature rolled samples. At both the reductions, cryorolled samples exhibited better hardness and strength compared to the room temperature rolled samples and the enhanced properties are attributed to the higher dislocation density of the cryorolled samples. The electron backscatter diffraction results indicated that the grains are submicron in size in rolled conditions. It also revealed that majority of the fraction of special grain boundaries are Σ1 boundaries with decreasing tendency of Σ3 boundaries. Quantitative contributions of different strengthening mechanisms were performed on the rolled samples and it was observed that significant contribution comes from grain boundary strengthening.