b'Electric current enhancedEnhanced diffusion welding Alloy 617 using electric field assisted sintering diffusion welding to fabricateenables manufacturing of high-temperature compact heat exchangers compact heat exchangerswith improved material properties and higher energy efficiency.for nuclear applications T he diffusion welding of Alloy 617 to manufacture compact heat exchangers is of strong interest for various applications, including advanced reactor design. Previous endeavors to diffusion weld Alloy 617 using hot pressing reported limited grain boundary migration across the interface due to extensive precipitation along mating surfaces. Bonds of this nature have been observed to reduce the elevated-temperature mechanical properties compared to the wrought materials. The goal of this research was to successfully diffusion weld Alloy 617 PROJECT NUMBER:using electric field assisted sintering (EFAS), achieving microstructural continuity 21A1050-120FP across the interface and enhanced mechanical properties. For this objective, diffusion welding using EFAS was conducted and the grain growth and material properties TOTAL APPROVED AMOUNT:were compared to their hot-pressed counterparts. The effects of EFAS processing $1,214,000 over 3 years parameters on microstructural features were revealed. It was observed that PRINCIPAL INVESTIGATOR:optimized EFAS temperatures produced superior interfacial grain growth across the Xinchang Zhang interface compared with hot-pressed samples. The down-selected parameters were used for process scaleup to fabricate Alloy 617 plates that meet the requirements CO-INVESTIGATORS: specified in the American Society of Mechanical Engineers Boiler and Pressure Vessel Jorgen Rufner, INL Code Section IX. Additionally, multiphysics modeling was performed to understand Michael McMurtrey, INL temperature distribution within the stack and to support tooling design for process Ryann Bass, INL scaleup. Alloy 617 plates that meet the size requirements were successfully Tate Patterson, INL fabricated using EFAS. Mechanical testing was performed on the welded plate to reveal the mechanical behavior. This research demonstrated a highly energy efficient approach that enables enhanced diffusion welding of Alloy 617 to make compact heat exchangers that benefit energy efficiency and performance of advanced systems. The novelty of this research resulted in multiple achievements, including intellectual property, peer reviewed publications, and presentations. In addition, collaborations with university and industry partners were established, and external funding was received to further investigate integrating advanced manufacturing techniques to manufacture compact heat exchangers.98'