Microstructural characterization of Haynes® 242™ alloy

A microstructural characterization has been performed on a HAYNES 242 nickel-molybdenum-chromium superalloy. Molybdenum was found to partition to the lenticular Ni-2(Mo,Cr) precipitates whereas iron, aluminum, silicon, manganese and nickel were found to partition to the gamma matrix. Chromium was not found to partition significantly between the phases. Atom probe tomography and energy-filtered transmission electron microscopy core-loss images revealed boron, molybdenum, chromium, phosphorus and carbon segregation to the grain boundaries. Despite the size of the precipitates being larger after a two-step heat treatment of 16 h at 704 degreesC + 16 h at 650 degreesC compared to a one-step heat treatment of 48 h at 650 degreesC, no significant differences were found in the mechanical properties or the compositions of the phases. Published by Elsevier Science B.V.