Effect of Re Addition and Withdrawal Rate on the Solidification Behavior of Directionally Solidified Superalloy AM3

The influence of Re addition and withdrawal rate on the solidification behavior of the first generation single crystal superalloy AM3 was investigated by directional solidification and quenching experiments. The primary dendrite arm spacing and eutectic volume fraction were measured from directionally solidified superalloy AM3 with different Re contents. It is found that the primary dendrite arm spacing is determined by the withdrawal rate, and Re does not influence on the value. The eutectic fraction increases with increasing Re addition. Partition coefficients of alloying elements were investigated with energy-dispersive X-ray spectrometry (EDS) analysis. The data was submitted to a statistical treatment to establish the solidification path, and the partition coefficients were measured by fitting the curve with a modified Scheil formula. It is shown that the addition of Re results in bigger microsegregation of alloying elements in directionally solidified AM3 superalloy.