Sub-solidus melting of directionally solidified Rene 80 superalloy during solution heat treatment

The microstructure of directionally solidified Rene 80 (DS Rene 80) superalloy in the standard solution heat treated condition was examined. Sub-solidus incipient melting was observed, which was found to be caused by the liquation of terminal solidification reaction products present in front of the c–c0 eutectic in the as-cast alloy. Based on the differential scanning calorimetry (DSC) measurements, and microstructural examination of heat-treated and water-quenched specimens, sub-solidus incipient melting in the alloy is likely to occur below 1,160 C, and this is a key factor to be considered in the development of a suitable solution heat treatment scheme for DS Rene 80.