| Advanced nuclear energy systems(Generation IV reactors)are the key to solving mankind’s energy problems,and materials are a major constraint to the development of nuclear energy.High entropy alloys have excellent mechanical and irradiation resistance properties such as high hardness and corrosion resistance,making them one of the most promising candidates for advanced nuclear energy systems.The structural components of advanced nuclear energy systems,such as fuel cladding and the first wall,are subjected to extreme conditions of high temperature,high irradiation,and high corrosion for long periods of time,resulting in degradation of material properties and seriously harming the safety of reactor operation.Irradiation damage and the resulting hydrogen and helium can change the microstructure of the material,causing swelling,embrittlement,and hardening,which is one of the main causes of material degradation.In addition,the simultaneous presence of hydrogen and helium further enhances the irradiation damage,resulting in complex synergistic effects.Therefore,the study of the synergistic effects of hydrogen/helium in high-entropy alloys and behaviors of irradiation-induced hardening can guide the development of new material candidatesIon irradiation has the advantages of high irradiation damage rate,controllable parameters,and no material activation after irradiation,and is an internationally recognized method for the study and testing of advanced nuclear energy materials.In this paper,Co Cr Fe Mn Ni high-entropy alloy was irradiated with 270 ke V helium ions and 140 ke V hydrogen ions at 450 °C,500 °C,550 °C and 600 °C with helium ions alone and hydrogen/helium ions simultaneously,respectively.The helium-hydrogen synergistic effects in Co Cr Fe Mn Ni high-entropy alloys under different irradiation conditions and behaviors of irradiation-induced hardening were investigated,and a brief evaluation of the Co Cr Fe Mn Ni high-entropy alloys was made.The main results of the work obtained in this paper are as follows:1.The S-parameters of the samples after simultaneous irradiation with hydrogen/helium ions are significantly larger than those of the samples after irradiation with helium ions,indicating that the irradiation damage produced by simultaneous irradiation with hydrogen/helium ions is larger than that produced by irradiation with helium ions,which is a result of the hydrogen-helium synergistic effect,and the mechanism behind this may be related to the different behaviors of the He-V complex and He-H-V complex structures formed by helium and vacancies as well as helium and hydrogen and vacancies,respectively.2.The slope of the S-W curve of the sample after helium ion irradiation changes at different temperatures,while the slope of the S-W curve of the sample after simultaneous hydrogen/helium ion irradiation is the same at different temperatures,indicating that the He-H-V complex produced inside the high-entropy alloy after simultaneous hydrogen/helium ion irradiation has better thermal stability than the He-V complex produced after helium ion irradiation.3.The Co Cr Fe Mn Ni high-entropy alloy is a simple face-centered cubic solid solution structure with a grain size of about 104 μm.Nanoindentation measurements of the Co Cr Fe Mn Ni high-entropy alloy show that it has a higher nanohardness than the P91 ferritic martensitic steel,and the irradiation hardening of the Co Cr Fe Mn Ni high-entropy alloy is much less than that of the latter,showing excellent resistance to irradiation hardening. |
