"Radiation-Induced Defect Evolution in Tungsten and Tungsten Alloys Under Heavy Ion Irradiation" 

Chang Xia, MSE PhD Candidate 

Advisor: Professor Haiyan Wang

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ABSTRACT

In recent energy research, fusion reactions have attracted substantial attention, particularly following the milestone achievement of net energy gain at the National Ignition Facility. This success has further intensified interest in plasma-facing and fusion wall materials, which are indispensable for maintaining stable reactor operation. Research on fusion wall materials has therefore focused on identifying candidates capable of withstanding extreme temperatures and irradiation conditions while ensuring long-term structural stability. Tungsten, as a leading candidate material, requires detailed investigation of its microstructural evolution and changes in mechanical properties under prolonged exposure. A key approach for accelerated testing is the use of heavy-ion irradiation to rapidly accumulate damage doses. This method allows researchers to simulate, within laboratory timescales, the levels of irradiation damage that would otherwise take years to develop inside a fusion reactor. Different heavy-ion species and their effects on tungsten and tungsten alloys are thus reviewed in detail. To evaluate irradiation effects, transmission electron microscopy (TEM), in-situ TEM, and hardness measurements are commonly employed. This review first discusses the defect types introduced by heavy-ion irradiation, followed by the influences of dose, irradiation temperature, and related parameters. To clarify the roles of microstructure and composition in irradiation response, both coarse-grained and nanocrystalline tungsten are examined. In addition, the effects of alloying are analyzed to better understand how transmutation and solute elements contribute to microstructural evolution and mechanical property changes.