Quantitative study of dimensional stability mechanism and microstructure evolution during precipitation process of 2024Al alloy

摘要

In this paper,we were devoted to quantitatively analyzing the dimensional change of 2024 Al alloy during the aging process.Types of precipitates have been defined and the corresponding volume fraction has been measured with Transmission Electron Microscopy(TEM)and Three-Dimensional Atom Probe Tomography(3 D-APT).Guinier-Preston-Bagaryatsky(GPB)zone(0.86 vol.%)was found after aging for 8 h.GPB zone(0.17 vol.%)and S'phase(1.02 vol.%)was found after aging for 24 h.The reduced dimensional change was attributed to the reduction of matrix lattice parameter.Relative to the initial supersaturated solid solution state,the lattice strain of-2.79×10^(-5)and-5.16×10^(-5)was produced after 8 h and 24 h aging respectively.The difference of the lattice parameters between the precipitates and matrix was also considered.A model was established to quantitatively describe the relationship between the precipitation process and dimensional change of 2024 Al alloy.