Heat Treatment of a Ni3Al-based Single Crystal Alloy IC32

IC32 is a new type of Ni3Al-based single crystal alloy, which has been designed to serve at 1200 degrees C. The effect of heat treatment on the microstructure of single crystal superalloy IC32 was investigated. The microstructure after heat treatment under different solution and aging temperature was examined by using optical microscope (OM), scanning electron microscopy(SEM) and electron probe microscopic analyzer (EPMA). The as-cast microstructure of IC32 consisted of a two-phase gamma/gamma' microstructure, and primary bulky gamma' phase which priciptated in the interdendritic region. The incipient melting temperature of IC32 is 1360 degrees C, and the heat treatment window is about 40 degrees C. Considering high contents of refractory elements Re and Ta, a complicate 18 hours solution heat treatment at different temperatures was conducted to elimate the segregation and dissolove the primary bulky gamma' phase. The optimum heat treatment of IC32 alloy is 1325 degrees C/4h+1335 degrees C/4h+1345 degrees C/10h, ac + 1165 degrees C/2h, ac + 870 degrees C/32h, ac.