Effect of Ca on hot tearing susceptibility of WE43 alloy

The effect of Ca on the hot tearing susceptibility (HTS) of WE43 alloy was systematically investigated in this study. The results revealed a significant reduction in HTS with the addition of Ca. The tear volume in WE43-xCa alloys (x = 0, 0.5, 1.0, and 2.0 wt%) was accurately quantified using a Micro-CT system, serving as an indicator for HTS. The lowest HTS was observed in the WE43–2.0Ca alloy, associated with the precipitation of a substantial amount of the Mg2Ca phase. The addition of 2.0 wt% Ca significantly promotes the enrichment of rare-earth eutectic and increases the residual liquid eutectic, resulting in complete healing of the hot tear. The highest HTS was observed in the WE43 alloy due to its low residual liquid eutectic fraction and the inevitable presence of Y2O3 inclusion. Additionally, Ca alloying refined grain size and reduced the susceptible freezing range of the alloys, which can reduce the shrinkage strain acting on the grain boundary per unit at the hot spot. Furthermore, the study investigated the unique morphology of the second phase flat interfaces in the healing region of WE43–2.0Ca alloy. Two possibilities for forming the flattened interface and its effect on HTS are inferred.