Influence of pre-deformation on aging precipitation behavior of three Al-Cu-Li alloys

Abstract

The influence of pre-deformation on aging precipitates of three near peak-aged Al-Cu-Li alloys, 1460 alloy with a low Cu/Li ratio (1.46), 2050 alloy with a high Cu/Li ratio (4.51) and 2A96 alloy with a medium Cu/Li ratio (2.97), was investigated. The strength of the aged alloys is enhanced by the pre-deformation. The effectiveness of pre-deformation on precipitates is dependent on the alloy's composition. With increasing the pre-deformation, the population density of T1 (Al2CuLi) precipitates increases in all three Al-Cu-Li alloys and their diameter decreases in 2050 and 2A96 alloys, and the greatest effectiveness is observed in 2A96 alloy. The pre-deformation also increases the population density of θ′ (Al2Cu) precipitates and decreases their diameter in 2050 and 2A96 Al-Li alloys, but the effectiveness is smaller compared to that on T1 precipitates. In 1460 alloy subjected to two-step aging at 130°C for 20 h followed by 160°C for 12 h, the main precipitates are δ′ (Al3Li). At 2%-6% pre-deformation, GP-I zones form and pre-deformation displays little influence. Eight percentage pre-deformation promotes θ″/θ′ precipitation and increases their population density.