Wang, Jian. In-situ observation of microstructural stability under dual-beam irradiation in interface/microstructure-manipulated nickel alloys

Principal Investigator
First Name:
Last Name:
University of Nebraska-Lincoln
Team Members:
Name: Institution: Expertise: Status:
Qing Su University of Nebraska-Lincoln Electron Microscopy, ion beam interaction, characterize irradiation induced defects Faculty
Xiaoyuan Lou Auburn University Corrosion, stress corrosion cracking, sensors, Metallurgy, high temperature material, additive manufacturing, structural materials, Oxidation Faculty
Michael Nastasi University of Nebraska-Lincoln Ion solid interaction, irradiation induced defects in materials Faculty
Experiment Details:
Experiment Title:
In-situ observation of microstructural stability under dual-beam irradiation in interface/microstructure-manipulated nickel alloys
Describe the work that you are proposing in detail. Please include as many specifics as possible (e.g., dose, dose rate, ion energy, types of ions, beam line x-ray energy, irradiation temperature, analysis temperature, atmosphere, etc.):
Here we propose the Ni-W and Ni-Mo eutectic alloys can be tuned via composition and heat treatment to have nanoscale fibrous/laminated microstructures containing thermally stable metal-intermetallic interfaces. The main scientific question being addressed in this project is whether high temperature stable nanostructured Ni-W and Ni-Mo eutectic alloys has high radiation tolerance and what composition can achieve maximum radiation tolerance. The Ni-W and Ni-Mo eutectic alloys with different compositions will be prepared by powder-based laser direct energy deposition additive manufacturing (AM). This approach allows to build continuously graded specimens with compositional gradients, which offers the opportunity to microstructurally characterize a range of interested chemical compositions. Since this proposed work focuses on interface and microstructure development, continuous composition library will result in a rapid understanding of the potential effects of hypo-eutectic, eutectic and hyper-eutectic compositions on microstructure. These Ni-W and Ni-Mo eutectic alloys will be subjected to dual irradiation (1 MeV Kr irradiation plus simultaneous 12 keV He implantation). To better mimic the nuclear reactor environment, irradiation will be carried out at room and elevated temperatures up to 750 °C with different He/dpa levels.
Technical Abstract
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.