Microstructure Refinement of As-Cast Single Crystal Superalloys by Re-Solidification

Recently identified re-solidification behaviour of heavily alloyed single crystal super¬alloys has been incorporated into the Bridgman method. The process variables of resolidifcation temperature and mould withdrawal rate have been optimized. The microstructure, microporosity and eutectic phase fraction of re-solidified specimens were analyzed and compared with conventionally cast single crystal specimens. The potential advantage of this modified method has been illustrated by performing solution heat treatments on both re-solidified and normally cast specimens followed by eutectic phase fraction analysis.