Effects of microstructure on tensile properties of AA2050-T84 Al-Li alloy

Abstract

The effect of microstructure evolution on the tensile properties of 2050 Al−Li alloy thick plate aged at 150 °C with 80 mm in thickness (t) was studied from a microstructural perspective. Scanning electron microscope, optical microscope, transmission electron microscope and X-ray diffractometer were used to explore the surface (t/6), interlayer (t/3) and center (t/2) thickness layer of this alloy. Results show that the secondary phases on grain boundaries, precipitates and textures vary depending on the thickness location. The precipitation strengthening has a stronger influence on the alloy along the rolling direction than the transverse direction from the under-aged to the peak-aging condition; however, its effect on the anisotropy is insignificant. The higher Taylor factor (M) value caused by stronger β fiber rolling textures and the intergranular phases is the main reason that leads to the highest strength at the t/2 position along the rolling direction. The M-value has a limited change at different thickness layers along the transverse direction, which causes the same tensile strength.