Analysis of the solidified structure of rheocast and VADER processed nickel-base superalloy

Conventional ingot processing of highly alloyed compositions results in a cast product which suffers from extensive macrosegregation, hot tears, and heterogeneities. By controlling the solidification journey, one can produce a fine grained cast product. This is achieved by manipulating the melt in the mushy zone. Rheocasting and vacuum arc double electrode remelting (VADER) are two such technologies where the melt is processed in the mushy zone. IN-100, a nickel based superalloy, was rheocast as well as VADER processed. The resultant cast structures are analysed, compared and discussed both on micro- and macrostructural levels. The effect of the rheocast processing variables (stirring speed, time and temperature) on the cast microstructure are also discussed