Investigation on melt concentration during thermal stabilization before directional growth in a Mg–Li eutectic alloy in presence of element volatilization

The initial melt concentration C for following directional solidification has been confirmed to be controlled by temperature gradient zone melting (TGZM) during thermal stabilization in previous studies. However, the accurate prediction of C has not been reported in the case of element volatilization before. In the present work, the hypoeutectic Mg-7.3Li alloy is selected to investigate the relationship between the melt concentration C and thermal stabilization process in presence of lithium volatilization. The increase of C has been shown to be interrupted when the thermal stabilization time is long, which is distinct from other alloys where no element volatilization exists. The theoretical analysis has been performed to predict C after thermal stabilization, and both the TGZM effect and Li loss caused by lithium volatilization during thermal stabilization are taken into account. The present prediction shows excellent agreement with the experimental result in Mg-7.3Li alloy, confirming the influence of lithium volatilization. Thus, this work can shed light on the prediction of C during directional solidification of alloys in presence of element volatilization.