Localized dissolution of grain boundary T1 precipitates in Al-3Cu-2Li

Abstract

AbstractTransmission electron microscopy (TEM) was employed to investigate the dissolution behavior of nanocrystalline grain boundary T1 precipitates in Al-3Cu-2Li. These grain boundary T1 plates exhibit an orientation relation with matrix, with the (1-11)α-Al parallel to (0001)T1 and [022]α-Al parallel to [10-10]T1, which is similar to the orientation relationship of T1 plates formed within grains. TEM studies showed that these grain boundary T1 plates react readily in moist air. As a result of the localized dissolution, the Cu-rich clusters form onto T1, which is consistent with the localized dissolution behavior observed in nanocrystalline S phase in Al-Cu-Mg.