Effects of deformation temperature on second-phase particles and mechanical properties of 2219 Al-Cu alloy

Abstract

In this study, an age-hardenable 2219 Al–Cu alloy was severely deformed by multidirectional forging (MDF) at 360–510°C, followed by solution treatment and T8 aging treatment. The evolution of the second-phase Al2Cu particles and the mechanical properties of the T8-aged samples were examined. The results indicated that a higher volume fraction and a more disperse distribution of the fragmented coarse particles were obtained for the sample deformed at low temperatures. The fragmented coarse particles were still difficult to sufficiently dissolve in the Al matrix in the subsequent solution treatment and could act as crack initiation sites, thereby reducing the mechanical properties of the alloy. With increasing the temperature of MDF, the number of coarse particles was gradually decreased, and the particles exhibited a more spheroidized shape after MDF. Correspondingly, more Cu atoms were dissolved in the Al matrix in the subsequent solution treatment, and the uniformity and density of the precipitates after T8 aging were improved. Thus, the mechanical properties of the T8-aged forgings were improved with increasing the temperature of MDF. The optimal mechanical properties were obtained when the deformation temperature was 510°C, with ultimate tensile strength of 431.2MPa, yield strength of 341.3MPa, and elongation of 6.5% at room temperature.