Microstructural characterization of Haynes® 242™ alloy

Thermodynamic Assessment of Hot Corrosion Mechanisms of Superalloys Hastelloy N and Haynes 242 in Eutectic Mixture of Molten Salts KF and ZrF4

“…A microstructural characterization of a Haynes 242 nickel-molybdenum-chromium superalloy was performed. 29 Molybdenum was found mostly in the Ni 2 (Mo,Cr) precipitates, whereas iron, aluminum, silicon, manganese, and nickel entered mostly the austenitic FCC-matrix. Chromium was not found to partition significantly between the phases.…”

“…29 Typically, quasi-binary diagrams (property diagrams) are constructed and used to help better understand a metal's phase composition as a function of temperature and pressure. 22,23 Today, such diagrams can be studied using well-regressed thermodynamic databases and fast, efficient algorithms of the global Gibbs energy minimization to establish equilibrium conditions.…”

“…In spite of the size of the precipitates being larger after a two-step heat treatment of 16 hours at 704°C + 16 hours at 650°C compared to a one-step heat treatment of 48 hours at 650°C, no significant differences were found in the mechanical properties or compositions of the phases. 29 The formation of the Ni 2 M intermetallic phase takes place at temperatures around 400°C as shown in Figure 5. However, overall, this is a reasonable set of phases to be expected for Haynes 242 at this temperature range because the alloy's ultimate microstructure and phase composition will be determined by the heat treatments used during thermomechanical processing.…”

Delineating the roles of Cr and Mo during ordering transformations in stoichiometric Ni2(Cr1− ,Mo ) alloys

“…In commercial Ni-based alloys, the evolution kinetics of the Ni 2 (Cr, Mo) phase varies from one alloy to another due to different concentrations of Cr and Mo solutes in them. For example, prolonged ageing is required for the formation of this phase in Alloy 625 (containing Cr = 21.73 and Mo = 8.82 (wt.%)) [11], while, it forms within a short time in Haynes 242 (containing Cr = 9.3 and Mo = 16.4 (wt.%)) [12]. Due to significant effect of the ordered Ni 2 (Cr, Mo) phase on mechanical properties, interest has now shifted towards understanding its thermal stability with different Cr and Mo solutes in these alloys.…”

Characterization of the Ni–Mo–Cr superalloy subjected to simulated heat-affected zone thermal cycle treatment

“…So, further study with regard to its constitution needs to be carried out. In addition, previous researches usually laid emphasis on the microstructure change while the Ni-Mo-Cr alloys underwent long-term exposure to elevated temperature (600-900°C) and tried to relate the microstructure with mechanical properties [23][24][25][26][27][28]. Sufficient facts [26][27][28] have clearly stated that Ni-MoCr belong to age-hardening alloys and the long range ordered (LRO) phases precipitating in the alloy, like Ni 2 (Cr, Mo), are responsible for its strengthening.…”