Thermodynamic Modeling and Experimental Measurement of Precipitation Formation during Dynamic Recrystallization for Magnesium Alloys

摘要

Magnesium alloys have low formability at room temperature associated with its hexagonal closed pack structure. Formation of precipitates during deformation may pin the grain boundary and reduce the final grain size, which literally means the improvement of formability. The aim of this study is to design magnesium alloys that are capable of forming precipitate during hot deformation. Thermodynamic modeling software, FactSage, has been used to design Mg-Al-Sn alloys based on forming target Mg_2Sn precipitate at hot deformation temperatures between 250 and 350°C. Uniaxial compression at elevated temperatures has been performed to simulate the hot deformation behaviour as well as to enhance the formation of precipitates. Strain rates used in this study were in the range of 1.0 to 0.001s~(-1) for a constant deformation degree of 90%. It was found that the formation of precipitate depends on deformation temperature and strain rate. Measured amounts of precipitate were compared with the calculated equilibrium results from FactSage.