Aging behavior of an Al-Cu-Mg alloy

Effect of aging temperature on precipitation behavior and mechanical properties of an AA2519 alloy was examined. Long-term natural aging provides the best combination of strength and ductility by the precipitation of dense Guinier-Preston and Guinier-Preston-Bagaryatsky zones. This phenomenon, called delayed hardening, has the same origin as the rapid hardening in AA2X24 alloys subjected to artificial aging. At 190 degrees C, high density of theta ''-phase provides high strength. Peak aging is characterized by insignificant increase in strength associated with additional precipitation of theta'-phase. The overaging leads to the formation of precipitate structure dominated by theta'-phase. The formation of theta ''- and theta'-phases can consume similar to 0.7 and similar to 3.3%Cu, respectively. Despite this, the number density of theta ''-phase precipitates is higher than that of theta'-phase ones by a factor of similar to 40. The theta ''-phase is effective strengthening agent in the AA2519 alloy. The Omega-phase plates with a very high aspect ratio (AR) > 100 precipitate during artificial aging. (C) 2018 Elsevier B.V. All rights reserved.