Investigation on laser beam remelted Al–Cu–Li alloy part I: Segregation and aging behavior at grain and dendrite boundaries

The segregation feature and its influence on the aging behavior of laser beam remelted 2A97 Al–Cu–Li alloy were investigated. Scanning electron microscopy, transmission electron microscopy, and energy dispersive spectrum methods were employed to analyze the microstructures, segregations, and structures of precipitates. It is revealed that segregations of Cu, Mn, and Zn occurred at the grain and dendrite boundaries of the as remelted and aged alloy, and co-segregation of Mg and Zn took place after aging. The dominant intermetallic phases at the segregation bands varied from TB (equiaxed zone) + θ (columnar dendrite zone) for the as remelted specimen to TB for the 155 °C-aged to T1 for the 175 °C-aged. Our results can provide an in-depth insight into the mechanism of the segregation effect on aging precipitation in laser beam welded Al–Cu–Li alloys.