The objective of this work is to develop nickel (Ni)-based alloys through engineered interfaces and microstructures that must be thermally stable at molten salt reactor operation temperatures above 750 oC. Nickel-Tungsten (Ni-W) and Nickel-Molybdenum(Ni-Mo) alloys will be tuned through heat treatments which develop thermally stable metal-intermetallic eutectic structures. The primary hypothesis is that these thermally stable nanoscale interfaces can trap and manipulate He and radiation-induced point defects, and provide significantly enhanced radiation tolerance, similar to or superior to those observed in other metallic nanolayered structures. The successful completion of this project will be the development of an innovative kind of Ni-based alloys that will provide revolutionary gains in materials properties resulting in significant enhanced reactor performance. The composite will possess good mechanical properties, be capable of operation at temperatures greater than 750 oC, and have extreme radiation tolerance. This will be accomplished by optimizing the Ni-based alloys composition and their microstructure for maximum performance in a reactor environment. In addition, we will deliver a new understanding of how thermally stable Ni/intermetallic interfaces in Ni-based alloys affect, influence, and enhance irradiation, mechanical, and Helium implantation performance. Through the in-situ dual-beam irradiation study of the Ni-based eutectic alloys, the research team will have understanding that can be directly used in the development of Ni-based alloys with direct application to structural components, and provide an important contribution to the state of knowledge in reactor materials science.