Dynamic recrystallization behavior of Mg–Li–Al–Nd duplex alloy during hot compression

Abstract

In order to evaluate the dynamic recrystallization (DRX) behavior of as-cast Mg–9.15Li–3.23Al–1.18Nd duplex magnesium alloy, a series of compression test with a strain of 0.7 were performed in temperature range of 473–673K and strain rate range of 0.001–1s−1 on a Gleeble3500 thermo-mechanical simulator. The apparent characteristics of flow stress curves obtained in dual phase α+β were analyzed in term of different dependence of flow stress to temperature and strain rate and different microstructural evolutions. Results showed that the DRX process could easily occur in β-Li phase, whereas in the α-Mg phase was retarded. Meanwhile, the globularised morphology of the α-Mg in a matrix was the characteristic feature of the micrographs in the track microstructural evolutions of the α-Mg phase. Based on the regression analysis for the Arrhenius type equation of flow behavior, the apparent average activation energy of deformation was determined as Q=126.9285kJ/mol. The activation energy of Mg–Li alloys could be obviously reduced by adding Li. The kinetics of DRX evolution was calculated as XDRX=1−exp[−0.01689((ε−εc)/ε∗)1.8599]. The DRX kinetic model was validated by means of microstructure observation. As the evolution of DRX was sensitive to temperature and strain rate, DRX grains easily occurred at higher temperatures and lower strain rates.