Characterization and modeling of concurrent precipitation in Mg-Al-Sn alloys using an improved Kampmann-Wagner numerical (KWN) model

Abstract

The concurrent precipitation microstructure of Mg17Al12 and Mg2Sn phases in AT72 (Mg-7Al-2Sn) magnesium alloy was quantitatively characterized using Scanning Transmission Electron Microscopy (STEM) based techniques. An improved Kampmann-Wagner numerical (KWN) model taking into account of the effects of non-spherical precipitates on growth kinetics and coupled with multicomponent thermodynamic and kinetic databases of magnesium alloys was used to simulate the evolution of the concurrent precipitation microstructure. Furthermore, the age hardening behavior of AT72 alloy was predicted by coupling the improved KWN model with a classical precipitation strengthening model. Simulation results show that a lower aging temperature will lead to finer and higher number density of both types of precipitates, providing improved aging hardening response. The addition of Al to Mg-Sn alloys can increase the driving force and precipitation kinetics of Mg2Sn phase. High-throughput KWN simulation was performed on the Mg-Al-Sn alloy system to demonstrate the application of the improved KWN model in optimizing the composition and heat treatment procedure in precipitation strengthened alloys.