Effect of solution treatment temperature on the microstructure and properties of 2055 aluminium alloy

Abstract

The effect of solution temperature on the microstructure and properties of modern Al-Cu-Li alloy (AA2055) was investigated. The strength of the alloy decreased with increasing the solution temperature. According to the results of SEM-investigations, optical metallography, as well as an X-ray phase diffraction, this trend is associated with the dissolution of the Al2Cu and Al2CuLi phases, as well as the recrystallization. The optimal properties were achieved demonstrated alloy solutionized at temperature of 510 °C: the yield strength, ultimate tensile strength, elongation-to-failure and hardness were 138 MPa, 319 MPa, 28% and 82 HV, respectively. Increasing the solution temperature from 500 to 540 °C leads to a drop in electrical conductivity from 22.7% IACS to 21.5% IACS. A significant drop in strength and electrical conductivity was observed in the samples solution treated at a temperature of 540 °C. This is associated with intensive recrystallisation of the microstructure and formation of pores due to overburning.