Phase precipitation and time-temperature-transformation diagram of Hastelloy X

Transmission electron microscopy (TEM) was employed to study the phase prec ipitation in Hastelloy X heat-treated at 750, 850, and 900 degrees C for 26 and 100 h. Phase identification was made by electron micro-diffraction and energy dispersion spectroscopy (EDS) X-ray micro-chemical analysis. In add ition to the fee matrix, four different precipitation phases were observed: M6C, M23C6, sigma, and mu. The current observations were combined with lit erature results to build a time-temperature-transformation (TTT) diagram fo r this alloy. This TTT diagram depicted time-temperature regimes where vari ous phases were formed; thus, it provided information about the general pre cipitation kinetics for the alloy. (C) 2000 Elsevier Science S.A. All right s reserved.