Unusual ageing behaviour of friction-stir welded Al-Cu-Mg alloy

摘要

The conventional peak-ageing treatment of friction-stir welded AA2519 resulted in precipitation of a stable 9-phase instead of the expected strengthening dispersoids of 9" and & thus degrading material strength. This phenomenon was attributed to acceleration of the precipitation kinetics due to grain refinement and over-ageing effect associated with the weld thermal cycle.