Effect of compressed pre-deformation on precipitation behavior of 7050 aluminum alloy during non-isothermal aging

Abstract

TEM, DSC and other techniques were used to characterize the heating aging precipitation behavior of 7050 aluminum alloy under compression pre-deformation conditions, and the influence law and mechanism of pre-deformation on heating aging precipitation were investigated. The results show that 7050 aluminum alloy can obtain excellent strength and corrosion resistance after pre-deformation heating aging, which can significantly shorten time and reduce energy consumption compared with traditional aging process. The pre-deformation greatly promotes the aging precipitation of 7050 aluminum alloy. The precipitate size increases rapidly as the increase of deformation during the same heating aging process, and its size distribution range increases rapidly too. The pre-deformation during heating aging process not only reduces the phase transformation activation energy of η' and η phases of 7050 aluminum alloy, but also accelerates the diffusion of solute atoms, which intensifies the Ostwald ripening and promotes the growth of precipitates. The calculation results show that the phase transformation activation energy of 7050 aluminum alloy gradually decreases with the increase of deformation. When the deformation amount increases from 0% to 18%, the phase transition activ-ation energy of η' and η phases decreases from 116.0 kJ/mol to 101.7 kJ/mol and 120.8 kJ/mol to 107.5 kJ/mol, respectively.

Keywords

• 7050 aluminum alloy
• pre-deformation
• heating aging
• precipitate kinetics
• phase transfor-mation activation energy