Effects of Solution Heat Treatment on Carbide of Ni-Cr-W Superalloy

The microstructure features of a kind of Ni-Cr-W superalloy after solution heat treatment at different temperatures (1230–1300 °C) for various time (10–120 min) were investigated by means of scanning electron microscope (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the precipitated phases of the alloy after solution heat treatment are identified as W-rich fcc M6C and Cr-rich fcc M23C6 carbides. The volume fraction of carbides decreases with increasing of the solution heat treatment temperature and time. At the temperature above 1270 °C for 120 min, most of carbides are dissolved into the Ni-matrix, and the carbides distributing at twin boundaries may be dissolved into the matrix first. M6C carbide has no any fixed orientation relationship with the Ni-matrix, but the angle of M23C6 (220) to the matrix (11) is 30°.