2, University of Michigan–Ann Arbor, Ann Arbor, Michigan, United States
3, University of Manchester, Manchester, , United Kingdom
Alloys based on the Ni-Cr binary system, such as alloys 625 and 690, are susceptible to mechanical property changes with thermal aging. A disorder-order phase transformation, which is the primary source of embrittlement, has been studied extensively in Ni-Cr model alloys to predict the transformation rate as a function of time, temperature and stoichiometry. Model and commercial alloys have been isothermally aged up to 10,000 hours and characterized via nanoindentation, atom probe tomography, and transmission electron microscopy. Additionally, these alloys have been ion beam irradiated to investigate the role of irradiation in accelerating the ordering kinetics. Preliminary results indicate change in stoichiometry do not change the ordering rate only the amount of ordered phase formed. Also, proton irradiation tends to accelerate the ordering process while Ni+ ion irradiation do not lead to ordering at the dose rates explored.