Comparative analysis of processing technology on the deformation behavior of Al alloys studied by synchrotron X-ray diffraction and tomography

Recycled Al-Cu alloys deteriorated mechanical properties due to stress concentration caused by coarse Fe-rich intermetallic (Fe-rich phases). This study aims to comparative analysis of processing technology of ultrasonic melt processing (USMP) or/and Al-Ti-B on microstructure and deformation behavior of Al-Cu alloys. They were investigated using various microscopy technique, such as, scanning/transmission electron microscopy, electron backscattered diffraction, and synchrotron X-ray diffraction and tomography. Heat-treated Al-Cu alloys contained primary Al phase, Al₇Cu₂Fe, and Al₁₅(FeMn)₃(SiCu)₂ phases. The grain sizes of the 0.7FeU (0.7 wt% Fe + USMP) and 0.7FeUB (0.7 wt% Fe + USMP + Al-Ti-B) alloys decreased by 25.7% and 42.2%, respectively, compared to the 0.7FeB (0.7 wt% Fe + Al-Ti-B) alloy. This refinement led to significant improvements in mechanical properties: yield strength, tensile strength, and elongation increased by 18.7%, 53.7%, and 216.7% for 0.7FeUB. USMP resulted in a refined and compact morphology of the Fe-rich phases, reducing stress concentration. Under tensile testing, the fine grains in the 0.7FeUB alloy rotated in multiple directions, promoting uniform plastic deformation and stress distribution. The maximum lattice strain before fracture increased by 100% and 142% for the 0.7FeU and 0.7FeUB alloys, respectively, compared to the 0.7FeB alloy. USMP also enhanced Cu and Mg solubility, resulting in fine precipitates and increased dislocation density, strengthened alloys through solid solution, precipitation, and dislocation strengthening.