Microstructural Characterization and Mechanical Property of Al-Li Plate Produced by Centrifugal Casting Method

Using a centrifugal casting method, along with deformation and aging, we produced a high-strength, low-anisotropy Al-Li plate. The electron probe microanalysis, transmission electron microscope, differential scanning calorimetry, and X-ray diffraction were used to clarify the evolution of strengthening phases. Experimental results showed that centrifugal-cast Al-Li plate consisted of intragrain delta '-(Al,Cu)(3)Li precipitate and interdendritic theta '-Al2Cu particles. After cold-rolling to a reduction ratio of 60% and annealing at 800 K for 90 min, both primary theta ' and delta ' were dissolved in solid solution. Aging at 438 K for 60 h led to the formation of two kinds of precipitates (needle-like T-1-Al2CuLi and spherical delta ' in two sizes), which acted as the main strengthening phases. The average values of ultimate tensile strength and yield strength for the anneal-aged plate reached 496 MPa and 408 MPa, with a total elongation of 3.9%. The anneal-aged plate showed mechanical anisotropy of less than 5%. The tensile fracture morphology indicated a typical intergranular fracture mode.