Materials Systems for the Future of Fusion Energy: Radiation Effects in High Heat Flux Materials II
Sponsored by: TMS Structural Materials Division, TMS: Nuclear Materials Committee, TMS: Additive Manufacturing Committee, TMS: Computational Materials Science and Engineering Committee, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Jason Trelewicz, Stony Brook University; Kevin Field, University of Michigan; Takaaki Koyanagi, Oak Ridge National Laboratory; Yuanyuan Zhu, University Of Connecticut; Dalong Zhang, Pacific Northwest National Laboratory

Wednesday 8:30 AM
March 2, 2022
Room: 203A
Location: Anaheim Convention Center

Session Chair: William Cunningham, University of California Santa Barbara


8:30 AM  
Deuterium Trapping and Release from Irradiation-induced Voids in Tungsten: Theory and Experimental Validation: Mikhail Zibrov1; Klaus Schmid1; 1Max Planck Institute for Plasma Physics
    Since tungsten (W) plasma-facing components in fusion reactors will operate at elevated temperatures, formation of irradiation-induced voids in them is expected. Based on the diffusion theory and the kinetic theory of the interaction of D2 gas with metal surfaces, we develop a self-consistent formalism for describing deuterium trapping and release from voids in metals. This formalism has been implemented into the diffusion-trapping code TESSIM. First, we performed 3D simulations of deuterium interaction with a single void in W to elucidate the main features of trapping and release. Significant differences compared with point defects are demonstrated. We also show that the commonly used equilibrium approximations often lead to erroneous results. Then we performed simulations for a system of voids in a 1D continuum approximation and compare them with 3D simulations. Finally, we applied our model for describing experimental deuterium thermal desorption spectra from voids in self-ion irradiated W.

8:50 AM  
Strain and Thermal Gradient Effects on the Transport Properties of Intrinsic Defects and Impurities in Tungsten: Enrique Martinez Saez1; Bochuan Sun1; Dimitrios Maroudas2; Nithin Mathew3; Danny Perez3; Sophie Blondel4; Dwaipayan Dasgupta4; Brian Wirth4; 1Clemson University; 2University of Massachusetts; 3Los Alamos National Laboratory; 4University of Tennessee, Knoxville
    Plasma-facing materials (PFMs) in a fusion reactor are expected to withstand stringent conditions, with high heat and particle fluxes that create strong gradients of temperature and concentration of diverse species. These species will then migrate in the presence of the afore-mentioned gradients and large strain fields. In this work, we use nonequilibrium molecular dynamics (NEMD) simulations to study the transport properties of H, He, and SIAs in the presence of a thermal gradient and different strain fields in tungsten. The NEMD simulations reveal that defects and impurity atoms tend to migrate toward the hot regions of the material (negative heat of transport). The resulting concentration profiles are in agreement with the predictions of irreversible thermodynamics. Furthermore, strain seems to play a critical role in the transport of these species significantly changing the concentration profiles. We demonstrate that the resulting steady-state profiles significantly depend on these fields.

9:10 AM  
Reduced Interstitial Mobility in W Based Transition Metal Ternary Systems: Younggak Shin1; Byeongchan Lee1; Keonwook Kang2; 1Kyung Hee University; 2Yonsei University
     Under neutron irradiation, at the presence of collision cascades, the mobility of point defects is a key property that governs the formation of volumetric defects such as interstitial clusters and voids. The mobility can be reduced by alloying due to the interaction between solutes and point defects.This study presents defect energetics and dynamics in W-Ta-Re systems, especially focused on the mobility of interstitial in such systems. The result shows that a Ta, a Re, and a W self-interstitial atom prefer to form a stable triple complex with strong attractive interaction. The interaction energy of the triple complex, which is higher than the corresponding one in W-Re binary systems, works as a primary dissociation barrier that reduces the interstitial mobility. Ta also restricts well-known 3D non-dissociative migration of W-Re mixed dumbbell and slows the migration further. Therefore, the multicomponent alloying may change the irradiated-damage mechanism in fusion environment.