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Radiation damage studies of bulk metallic glass materials under proton irradiation and radioprotection studies for METU-DBL

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2019
Uslu, Pelin
Suitable material selection is critical for the sustainability of missions in radiation environments. Radiation tests are required for candidate materials before being used in these environments. While neutron and heavy ion tests are often performed on materials intended for the nuclear reactors, proton tests are necessary for space applications due to them being the dominant radiation. Generally, crystalline materials are used in radiation environments but, new material search is ongoing. One of such new generation is bulk metallic glasses (BMGs). They have received much attention due to their superior physical, chemical, mechanical and magnetic properties compared to their crystalline counterparts. Especially, new generations of Fe-based BMGs have great potential for these environments due to high strength and hardness as well as good corrosion resistance. Mostly neutron and heavy ions tests exist in literature. Here, proton tests for these materials were performed and the effects of proton irradiation on Fe-based BMGs for space radiation were studied. Fe-based BMG was produced by arc melting and then suction casting into copper mold in the form of a 10 cm long cylindrical rod with a diameter of 3 mm. In addition, commercially available 304 and 316 SS were tested with 30 MeV protons. Structural, thermal, mechanical and magnetic characterization techniques were employed to examine the effects of proton radiation on these materials. These tests which are the first time such a study has been performed in Turkey, were conducted at the new METU-Defocusing BeamLine (DBL) facility located inside the Turkish Atomic Energy Authority (TAEA) SANAEM Proton Accelerator Facility (PAF). This facility uses 15-30 MeV protons with a flux between 10textsuperscript{5} - 10textsuperscript{11} p/cmtextsuperscript{2}/s to test electronics. Also, studies for radioisotope production and radiation protection of sensitive electronic devices of METU-DBL are also presented here. Characterization studies of irradiated materials showed that the point defects were formed on the both BMGs and stainless steels after the irradiation. Any surface damage or new phase occurrence were not observed on these samples. After the irradiation, point defects were observed on the samples.