Rapid Development of Radiation-Tolerant Advanced Alloys for Radio Frequency Actuators

New high-temperature, radiation-tolerant alloys show promise for improving performance of radio frequency (RF) actuators in future fusion reactors. These alloys must achieve multiple competing requirements: high strength at high temperature (~700 C), thermal & electricial conductivity on par with Cu, and low activation after neutron irradiation. Elemental composition limits for low-level waste disposal [S. Fetter, et al. Fus. Eng. and Des. 13.2 (1990): 239-246.] restrict the use of many element commonly used in high-performance Cu alloys to trace levels. For example the Nb concentration must be in the parts-per-million range, however GRCop high temperature Cu alloys have Nb concentrations in the range of several percent. This work presents a new development pathway to generate and characterize the performance of candidate alloys in a high throughput manner. First, physical vapor deposition (PVD) on a substrate wafer creates a sample with elemental composition gradients in two dimensions. Next, the sample is bombarded with high energy Cu ions to emulate neutron damage at greatly accelerated dose rates as compared with fission neutron irradiation. In-situ diagnostics allow real-time tracking of the change in thermo-elastic properties as a function of absorbed dose to identify the most radiation-tolerant compositions. Finally, larger samples of the most promising candidate alloys are evaluated with conventional mechanical and RF tests.