Experimental and modeling investigations of the non-isothermal and isothermal precipitations in an Al-Cu-Mg-Zr alloy with various pre-precipitation microstructures

The complex precipitation evolutions of Al-Cu-Mg alloys during both non-isothermal and isothermal thermal processes have been found to work on their mechanical properties and electrical resistivity. Modeling of the precipitation kinetics, electrical resistivity and strength evolution is therefore essential for optimizing heat treatment and processing of these alloys. In this work, in situ electrical resistivity monitoring during both non-isothermal and isothermal thermal processes and microstructural characterizations were conducted on an Al-Cu-Mg-Zr alloy with different pre-precipitation microstructures to provide fundamental insights of precipitation behaviors. The results showed that precipitation behaviors of Al-Cu-Mg-Zr alloy, such as the dominant strengthening phase, were highly dependent on preprecipitation microstructures and thermal history. A time-temperature-microstructure-properties map was established to unravel precipitation characteristics and their strengthening functions. The maximum hardness was indicated to be attributed to the combined presence of Guinier-Preston-Bagaryatsky (GPB) zones and fine S (Al2CuMg) phase. Further, in situ electrical resistivity was used as the main input data todevelop an improved model based on the classical Kampmann and Wagner type numerical model (KWN model). This integrated model could not only reveal precipitation kinetics but also well predict hardness evolutions of the studied alloy during non-isothermal and isothermal processes. (c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

Automated summary

The complex precipitation behaviors of Al-Cu-Mg-Zr alloy were investigated, and it was found that the pre-precipitation microstructures and thermal history significantly influenced the precipitation behaviors and strengthening functions. A time-temperature-microstructure-properties map was established to reveal the precipitation characteristics. Additionally, an improved model based on in situ electrical resistivity monitoring and the classical Kampmann and Wagner type numerical model was developed, which successfully predicted the hardness evolution of the alloy during both non-isothermal and isothermal processes.