Enhancing creep formability and mechanical properties of creep-aged AA2050 alloys via slow heating

In this work, a new creep aging route (pre-deformation+slow-heated creep aging, PSHCA) of AA2050 alloys was developed by the slow heating (20 degrees C/h) from 120 degrees C to 180 degrees C. The PSHCA alloy exhibits high creep strain with a simultaneous increase of strength and plasticity. The yield strength, ultimate tensile strength, and elongation reached 544 MPa, 581 MPa, and 11.1%, respectively. Both the rolling pre-deformation before aging and stress field during aging promoted the increased dislocation density and dense precipitation of T-1 phases in the aged alloys, hence, the strength was improved at the expense of plasticity. Meanwhile, the bimodal diameter distribution of T-1 phase of the PSHCA alloy and the enrichment of Ag atoms at T-1/matrix interface was promoted by slow heating, slowing down the thickening of T-1 phases. This further promoted the plasticity of PSHCA alloys while maintaining high strength. Additionally, the slow precipitation of T-1 phase at the early stage of aging promoted dislocation slip and thus improving the creep strain of PSHCA alloys. These findings pave a way in designing large-curved and high-performance Al-Li components by creep aging technology.